Abstract: Frequently, in data packages submitted for Marketing Approval to the CHMP, there is a lack of relevant head-to-head comparisons of medicinal products that could enable national authorities responsible for the approval of reimbursement to assess the Added Therapeutic Value (ASMR) of new clinical entities or line extensions of existing therapies.Indirect or mixed treatment comparisons (MTC) are methods stemming from the field of meta-analysis that have been designed to tackle this problem. Adjusted indirect comparisons, meta-regressions, mixed models, Bayesian network analyses pool results of randomised controlled trials (RCTs), enabling a quantitative synthesis.The REAL procedure, recently developed by the HAS (French National Authority for Health), is a mixture of an MTC and effect model based on expert opinions. It is intended to translate the efficacy observed in the trials into effectiveness expected in day-to-day clinical practice in France.
Abstract: We updated the 2002 Antiplatelet Trialists' Collaboration meta-analysis of antiplatelet therapy to assess the effects of aspirin alone in the secondary prevention of different types of thrombotic arterial disease. Results of randomized, placebo-controlled trials of aspirin in patients with confirmed cardiovascular disease were abstracted and synthesized by the Mantel-Haenszel method. We defined three cardiovascular disease groups according to the qualifying disease at entry: coronary artery disease (CAD), cerebrovascular disease (CRVD), and peripheral arterial disease (PAD). Results are given as odds ratios (OR) and 95% confidence intervals (95% CI). Compared with placebo, aspirin decreased significantly the risk of all-cause death in CAD and CRVD (OR = 0.80, 95% CI 0.75-0.86 and 0.91, 95% CI 0.85-0.98, respectively), and of vascular events in CAD, CRVD, and PAD (OR = 0.71, 95% CI 0.67-0.76, 0.87, 95% CI 0.82-0.93, and 0.50, 95% CI 0.29-0.88, respectively). The risk of non-fatal stroke was decreased in the CAD, CRVD, and PAD (OR = 0.64, 95% CI 0.50-0.83, 0.81, 95% CI 0.74-0.89, and 0.26, 95% CI 0.07-0.94, respectively). The risk of non-fatal myocardial infarction was decreased significantly in the CAD and CRVD (OR = 0.59, 95% CI 0.53-0.67, and 0.63, 95% CI 0.48-0.84, respectively), but not in the PAD (OR = 0.43, 95% CI 0.15-1.25). Aspirin nearly doubled the risk of major bleeds (OR = 1.87, 95% CI 1.51-2.32 for all clinical conditions). This meta-analysis confirms that aspirin decreases the risk of thrombotic events in patients with confirmed disease of the coronary, cerebrovascular, or peripheral artery beds.
Abstract: BACKGROUND: Infusion of saline attenuates the decrease in renal function induced by radiographic contrast agents among patients with chronic renal insufficiency. AIM: The Preventing Renal alteration in Coronary Disease (PRECORD) trial was a randomized trial to assess the effect on renal function of saline infusion during and after coronary angiography in 201 patients without severe chronic renal insufficiency (serum creatinine<140micromol/L). METHODS: All patients received standard oral hydration: 2000mL of tap water within the 24 hours after coronary angiography. Patients were randomized before the procedure to intravenous hydration (1000mL of 0.9% saline infusion) or no additional hydration. The infusion was started in the catheterization laboratory and continued for 24 hours. The primary endpoint was the change in calculated creatinine clearance between baseline and 24 hours after coronary angiography. The same ionic low osmolar radiographic contrast agent (ioxaglate) was used in all patients. RESULTS: Both groups had similar baseline characteristics, including age, serum creatinine, volume of contrast and proportion of patients undergoing ad hoc coronary angioplasty. The overall decrease in serum creatinine clearance 24 hours after the procedure was -3.44 (0.68)mL/min. The change in serum creatinine clearance 24 hours after the procedure was -2.81 (1.07)mL/min in the infusion group vs -4.09 (0.91)mL/min in the control group (p=0.38). CONCLUSION: Renal function is altered only slightly 24 hours after coronary angiography with standard oral hydration alone and is not affected by saline infusion started at the beginning of coronary angiography, even in patients with mild-to-moderate renal dysfunction.
Abstract: BACKGROUND: Despite guidelines establishing the need to perform comprehensive paediatric drug development programs, pivotal trials in children with epilepsy have been completed mostly in Phase IV as a postapproval replication of adult data. However, it has been shown that the treatment response in children can differ from that in adults. It has not been investigated whether differences in drug effect between adults and children might occur in the treatment of drug-resistant partial epilepsy, although such differences may have a substantial impact on the design and results of paediatric randomised controlled trials (RCTs). METHODS AND FINDINGS: Three electronic databases were searched for RCTs investigating any antiepileptic drug (AED) in the add-on treatment of drug-resistant partial epilepsy in both children and adults. The treatment effect was compared between the two age groups using the ratio of the relative risk (RR) of the 50% responder rate between active AEDs treatment and placebo groups, as well as meta-regression. Differences in the response to placebo and to active treatment were searched using logistic regression. A comparable approach was used for analysing secondary endpoints, including seizure-free rate, total and adverse events-related withdrawal rates, and withdrawal rate for seizure aggravation. Five AEDs were evaluated in both adults and children with drug-resistant partial epilepsy in 32 RCTs. The treatment effect was significantly lower in children than in adults (RR ratio: 0.67 [95% confidence interval (CI) 0.51-0.89]; p = 0.02 by meta-regression). This difference was related to an age-dependent variation in the response to placebo, with a higher rate in children than in adults (19% versus 9.9%, p < 0.001), whereas no significant difference was observed in the response to active treatment (37.2% versus 30.4%, p = 0.364). The relative risk of the total withdrawal rate was also significantly lower in children than in adults (RR ratio: 0.65 [95% CI 0.43-0.98], p = 0.004 by metaregression), due to higher withdrawal rate for seizure aggravation in children (5.6%) than in adults (0.7%) receiving placebo (p < 0.001). Finally, there was no significant difference in the seizure-free rate between adult and paediatric studies. CONCLUSIONS: Children with drug-resistant partial epilepsy receiving placebo in double-blind RCTs demonstrated significantly greater 50% responder rate than adults, probably reflecting increased placebo and regression to the mean effects. Paediatric clinical trial designs should account for these age-dependent variations of the response to placebo to reduce the risk of an underestimated sample size that could result in falsely negative trials.
Abstract: AIM: This systematic meta-analysis was performed to evaluate the intraocular pressure (IOP) lowering effects and tolerability of latanoprost, bimatoprost, and travoprost. METHODS: Clinical trials published up to July 2006 were thoroughly searched using all available databases and resources. The inclusion criteria were prospective randomized controlled clinical trials; patients with primary open-angle glaucoma or ocular hypertension; and prostaglandin monotherapy, without systemic/ocular medications or laser/surgery that could affect IOP within the past 3 months. Study quality was assessed with the Jadad scoring system, and potential bias was eliminated by robust statistical and independent reviews of publications. The main outcome measures were efficacy assessed by IOP (taken at 8 AM, noon, 4 PM, and 8 PM) change at 3 months from baseline and tolerability assessed by the incidence of conjunctival hyperemia. RESULTS: Eight trials were identified (n=1610 patients). IOP change from baseline was statistically significantly greatest with bimatoprost, compared with latanoprost at all time points [weighted mean (WM) 8 AM: WM=0.50 mm Hg; P=0.05; 95% confidence intervals (CIs) 0.01-0.99; noon: WM=1.17 mm Hg; P<0.001; 95% CI 0.68-1.66; 4 PM: WM=0.78 mm Hg; P=0.003; 95% CI 0.26-1.29; 8 PM: WM=0.67 mm Hg; P=0.04; 95% CI 0.02-1.32], and with travoprost during the daytime (8 AM: WM=1.02 mm Hg; P=0.004; 95% CI 0.32-1.72; noon: WM=0.86 mm Hg; P=0.02; 95% CI 0.12-1.59). Latanoprost and travoprost were comparable in their ability to reduce IOP at all time points (P<or=0.82). The incidence of hyperemia was less with latanoprost and travoprost [latanoprost vs. bimatoprost: relative risk=0.59; P<0.001; 95% CI 0.50-0.69; travoprost vs. bimatoprost: relative risk=0.84; P=0.05; 95% CI 0.70-1.00]. CONCLUSIONS: The findings suggest a greater efficacy of bimatoprost compared with latanoprost and travoprost, although the incidence of hyperemia was lower with the latter 2 agents.
Abstract: BACKGROUND AND OBJECTIVES: A relation between the size of treatment efficacy and severity of the disease has been postulated and observed as linear for a few therapies. We have called this relation the effect model. Our objectives were to demonstrate that the relation is general and not necessarily linear. STUDY DESIGN AND SETTING: We extend the number of observed effect model. Then we established three numerical models of treatment activity corresponding to the three modes of action we have identified. Using these models, we simulated the relation. RESULTS: Empirical evidence confirms the effect model and suggests that it may be linear over a short range of event frequency. However, it provides an incomplete understanding of the phenomenon because of the inescapable limitations of data from randomized clinical trials. Numerical modeling and simulation show that the real effect model is likely to be more complicated. It is probably linear only in rare instances. The effect model is general. It depends on factors related to the individual, disease and outcome. CONCLUSION: Contrarily to common, assumption, since the effect model is often curvilinear, the relative risk cannot be granted as constant. The effect model should be taken into account when discovering and developing new therapies, when making, health care policy decisions or adjusting clinical decisions to the patient risk profile.
Abstract: Severe myoclonic epilepsy in infancy (SMEI) is a rare, but severe disorder with seizures typically resistant to conventional antiepileptic drugs. The objective of the present study was to systematically review the literature on the available treatments for SMEI. Databases searched included Medline, Embase, and Cochrane. We used a fixed effect model to summarize the odds ratio of seizures rates and a logistic model to evaluate the influence of patient characteristics on treatment effect. We found 23 uncontrolled studies and 2 randomized controlled trials (RCTs) that compared stiripentol with placebo. Overall, 64 children aged between 3 and 20 years were included in the two RCTs. The odds ratio of responding to stiripentol relative to placebo was 32 (CI: 6.2, 161) and stiripentol reduced seizure rate by 70% (93%; 47%). The multivariate analysis does not suggest any differences within subgroups of participants and cotherapy. Results of uncontrolled studies in children with SMEI are potentially biased and do not provide valid information on the benefits and harms of treatments. The two RCTs identified, however, were performed with the same objectives and design and showed that seizure frequency is greatly reduced by stiripentol in children with SMEI after 2 months of treatment.
Abstract: INTRODUCTION: To compare the impact on overall survival (OS) of docetaxel-based chemotherapy versus vinca alkaloid-based regimens for first-line therapy of advanced non-small cell lung cancer. METHODS: A meta-analysis of all randomized, controlled trials comparing docetaxel- and vinca alkaloid-based chemotherapy was undertaken using MEDLINE, CANCERLIT, MEDSCAPE, Google Scholar, the Cochrane Library, the National Institutes of Health randomized, controlled trials register, and conference proceedings, supplemented by information from clinical study reports. All published and unpublished randomized, controlled trials (in any language) were included. Analysis was based on pooling individual logarithms of the hazard ratio for OS and the odds ratio (OR) for safety. RESULTS: From eight potentially eligible trials, seven were selected (n = 2867). Docetaxel was administered with a platinum agent (three trials), with gemcitabine (two trials), or as monotherapy (two trials). Vinca alkaloid (vinorelbine [six trials] and vindesine [one trial]) was administered with cisplatin (six trials) or alone (one trial). The pooled estimate for OS showed an 11% improvement in favor of docetaxel (hazard ratio = 0.89; 95% confidence interval: 0.82-0.96; p = 0.004). Sensitivity analyses considering only vinorelbine as a comparator or only the doublet regimens showed similar improvements. Grade 3/4 neutropenia and grade 3/4 serious adverse events were less frequent with docetaxel- versus vinca alkaloid-based regimens (OR = 0.59; 95% confidence interval: 0.38-0.89; p = 0.013 and OR = 0.68; 95% confidence interval: 0.55-0.84; p < 0.001, respectively). CONCLUSION: According to this meta-analysis, docetaxel is superior to vinca alkaloid-based regimens in terms of OS and safety for first-line therapy of advanced non-small cell lung cancer.
Abstract: AIMS: The impact on mortality outcomes of beta-blockers and calcium blockers in post-myocardial infarction (MI) has been suggested to be related to resting heart rate (HR) reduction. A meta-regression of randomized clinical trials was carried out to assess this relationship using weighted meta-regression of logarithm of odds ratio against absolute HR reduction. METHODS AND RESULTS: Twenty-five controlled randomized trials (21 with beta-blockers and four with calcium channel blockers) involving a total of 30 904 patients meet eligibility criteria, but only 17 documented changes in resting HR (14 with beta-blockers and three with calcium channel blockers). A statistically significant relationship was found between resting HR reduction and the clinical benefit including reduction in cardiac death (P < 0.001), all-cause death (P = 0.008), sudden death (P = 0.015), and non-fatal MI recurrence (P = 0.024). Each 10 b.p.m. reduction in the HR is estimated to reduce the relative risk of cardiac death by 30%. CONCLUSION: The meta-regression of the randomized clinical trials strongly suggest that the beneficial effect of beta-blockers and calcium channel blockers in post-MI patients is proportionally related to resting HR reduction. Furthermore, the absence of residual heterogeneity indicated that resting HR reduction could be a major determinant of the clinical benefit.
Abstract: The diagnostic value of sentinel lymph node mapping (SLNM) in patients with colorectal cancer (CRC) is controversial. Prognostic factors for CRC must be detected to improve its treatment. A PubMed query (key words: colorectal cancer, sentinel node) provided 182 studies on the sentinel lymph node (SLN) for CRC, the abstracts of which were reviewed. Altogether, 48 studies dealing with the diagnostic value of SLNM were selected from PubMed, and 6 other studies were retrieved from reviews. We compared the diagnostic value of SLNM with that of conventional histopathologic examination. We used the diagnostic accuracy odds ratio (DAOR) method. Because of significant heterogeneity, we chose the random effect model (Der Simonian and Laird). Statistics were performed on 33 studies, including 1794 patients (1201 colon and 332 rectum cancers). The mean SLNM failure rate was 10%. The global sensitivity and specificity of the SLNM were, respectively, 70% and 81%. The pooled DAOR was 10.7 (95% confidence interval 7.0-16.5). That means that a patient whose SLN is invaded has 10.7 times more risk to be node-positive than an SLN-negative patient. Lymphatic mapping appears to be readily applicable to CRC. One of the main reasons for the heterogeneity is the performance of the SLNM by Saha et al., whose data had better sensitivity (90%) than those in other studies. The SLNM technique should be better standardized in future studies. Understanding the cause of false-negative SLNs (9%) is a major issue to resolve before routinely using this technique in CRC management. The prognostic implication of micrometastases found in SLNs requires further evaluation.
Abstract: To investigate the potential benefits of two modes of evidence-based knowledge transfer ('active' and 'passive' modes) in terms of improvement of intention of prescription, knowledge, and real prescription in practice, we performed an open randomized controlled trial (CardioDAS) using a factorial design (two tested interventions: 'active' and 'passive' knowledge transfer) and a hierarchical structure (cluster of physicians for each department level). The participants were cardiologists working in French public hospitals. In the 'passive' transfer group, cardiologists received evidence-based knowledge material (available on Internet) every week for a duration of 1 year. In the 'active' transfer group, two knowledge brokers (EA, PN) visited the participating departments (every 2 months for 1 year, 2 h per visit). The primary outcome consisted in the adjusted absolute mean variation of score (difference between post- and pre-study session) of answers to simulated cases assessing the intention to prescribe. Secondary outcomes were the variation of answers to a multiple-choice questionnaire (MCQ) assessing knowledge and of the conformity of real prescriptions to evidence-based reference assessing the behavioral change. Twenty-two French units (departments) of cardiology were randomized (72 participating cardiologists). In the 'active' transfer group, the primary outcome was more improved than that in the control (P = 0.031 at the department level, absolute mean improvement of 5 points/100). The change in knowledge transfer (MCQ) was also significant (P = 0.039 at the department level, absolute mean improvement of 6 points/100). However, no benefit was shown in terms of prescription conformity to evidence. For the 'passive' mode of knowledge transfer and for the three outcomes considered, no improvement was identified. CardioDAS findings confirm that 'active' knowledge transfer has some impact on participants' intent to prescribe and knowledge, but no effect on behavioral outcome. 'Passive' transfer seems far less efficient. In addition, the size of the benefit remains small and its consequences limited in practice.
Abstract: CONTEXT: Statins inhibit HMG-CoA reductase, preventing synthesis of mevalonate but also of isoprenoids, which affect osteoclast activity. Amino-bisphosphonates share this effect. In vitro and in vivo, statins show convincing anabolic and anti-resorptive bone effects. However, in a clinical meta-analysis (MA), they did not prevent hip fractures. OBJECTIVE AND DESIGN: Our meta-analysis studied the impact of statins on bone mineral density (BMD) at various sites and compared the effects of lipophilic and more hydrophilic statins. DATA SOURCES: Our PubMed and Embase queries using two keywords (statins, BMD) were updated to October 2006. DATA COLLECTION: Two readers independently collected BMDs from studies. DATA SYNTHESIS: Twenty-one studies, mostly observational (three randomized controlled trials and one pseudo-randomized study), were assessed. Two studies were excluded (no control groups). Three studies could not be analyzed. The sixteen studies analyzed mainly included postmenopausal osteopenic women (2971 patients under statins). Statins significantly increased BMD at total hip (TH) and femoral neck (FN). Effect sizes (ESs) were modest: 0.21 at TH (95% confidence interval [CI]: 0.16-0.25) and 0.20 at FN (CI: 0.08-0.28). Among women, statins acted similarly (ES: 0.20 for TH and 0.18 for FN; CI: 0.14-0.25 and 0.06-0.31 respectively); lipophilic statins (simvastatin, lovastatin) almost entirely caused this effect, at both TH (ES: 0.20; CI: 0.15-0.26) and FN (ES: 0.22; CI: 0.06-0.37). CONCLUSION: Our findings of modest but statistically significant beneficial effects of statins on hip BMD should promote large double-blind randomized controlled trials on their bone effects, in view of their major beneficial cardiovascular effects with excellent safety profile.
Abstract: INTRODUCTION: Equivalence trials are actually frequently used to prove non-inferiority in anticoagulant therapy. Equivalence trials consist to demonstrate that two treatments are not too much different. This difference has to be under a margin previously determined. The margin corresponds to an efficacy loss that is defined to be acceptable, in accordance to the advantages due to the new treatment. The aim of this work is to explore the equivalence trial published in the thromboembolic disease by focus on the non-inferiority margin used. METHODS: We identified published equivalence trials in the venous thromboembolic disease, by a systematic search in Medline. We calculated the efficacy loss by reference with the value of the smallest effect size of the standard treatment compared to placebo. RESULTS: We found 9 equivalence trials used in venous thromboembolic disease. The mean value of the efficacy loss was 434%, and the median value was 357%. Eighty-five percent of the values of the efficacy loss were above 100%. DISCUSSION: Eighty-five percent of the equivalence trials conclude to equivalence despite a complete efficacy loss of the effect of the standard treatment compared to placebo. The results of equivalence trials should be interpreted warily. The corresponding non-inferiority margin should be chosen more rigorously and by reference with the value of the smallest effect size of the standard treatment compared to placebo.
Abstract: Noninferiority trials make it possible to show that the efficacy of a new treatment is not worse than that of the reference treatment, but not to conclude that efficacy is strictly equivalent. Even though a noninferiority trial is conclusive, there remains the possibility that the new treatment is inferior to the reference treatment (within the margin of the noninferiority margin set a priori, that is, before the results were known). A treatment shown not to be inferior does not represent therapeutic progress unless it has other advantages, in terms, for example, of tolerance or ease of use. Setting the noninferiority margin is a clinical and not a statistical problem. It requires determining the greatest acceptable loss of efficacy relative to the reference treatment. This loss of efficacy set by the noninferiority margin cannot exceed the efficacy of the reference treatment, since that could amount to loss of the entire treatment benefit.
Abstract: Results of meta-analyses may differ from those of megatrials only because of the bias that could be introduced by a unadequate methodology of some meta-analyses. A meta-analysis must be based on an exhaustive review of the literature - of all studies, those with negative as well as positive results. The quality of a meta-analysis depends on the methodological quality of the studies it analyzes; accordingly they must be selected according to strict methodological inclusion and exclusion criteria, defined a priori. The value of a meta-analysis is that allows a treatment strategy to be assessed in populations more heterogeneous than those in clinical trials. Nonetheless the heterogeneity of protocols, of dosing, and of outcome measures can lead to bias of the treatment effect estimation. Different analytic techniques must be used to assess possible publication or selection bias (the so-called "funnel plot" method) and potential sources of heterogeneity (heterogeneity test, meta-regression, etc.). Meta-analyses of individual data make it possible to assess the treatment effect according to patient characteristics. Prospective meta-analyses or those planned before clinical trials can help to limit data heterogeneity by making study protocols less varied (treatment, follow-up, evaluation, etc.).
Abstract: BACKGROUND: Results of randomized trials of angiotensin-converting enzyme inhibitors in patients with coronary artery disease (CAD) and preserved left ventricular function are conflicting. We undertook this study to determine whether long-term prescription of angiotensin-converting enzyme inhibitors decreases major cardiovascular events and mortality in patients who have CAD and no evidence of left ventricular systolic dysfunction. METHODS: We searched MEDLINE, EMBASE, and IPA databases, the Cochrane Controlled Trials Register (1990-2004), and reports from scientific meetings (2003-2004), and we reviewed secondary sources. Search terms included angiotensin-converting enzyme inhibitors, coronary artery disease, randomi(s)zed controlled trials, clinical trials, and myocardial infarction. Eligible studies included randomized controlled trials in patients who had CAD and no heart failure or left ventricular dysfunction, with follow-up omicronf 2 years or longer. Of 1146 publications screened, 7 met our selection criteria and included a total of 33 960 patients followed up for a mean of 4.4 years. RESULTS: Five trials included only patients with documented CAD. One trial included patients with documented CAD (80%) or patients who had diabetes mellitus and 1 or more additional risk factors, and another trial included patients who had CAD, a history of transient ischemic attack, or intermittent claudication. Treatment with angiotensin-converting enzyme inhibitors decreased overall mortality (odds ratio, 0.86; 95% confidence interval, 0.79-0.93), cardiovascular mortality (odds ratio, 0.81; 95% confidence interval, 0.73-0.90), myocardial infarction (odds ratio, 0.82; 95% confidence interval, 0.75-0.89), and stroke (odds ratio, 0.77; 95% confidence interval, 0.66-0.88). Other end points, including resuscitation after cardiac arrest, myocardial revascularization, and hospitalization because of heart failure, were also reduced. CONCLUSION: Angiotensin-converting enzyme inhibitors reduce total mortality and major cardiovascular end points in patients who have CAD and no left ventricular systolic dysfunction or heart failure.
Abstract: OBJECTIVE: The purpose of this study was to create a new instrument for the training of doctors in the use of forceps and to compare the trajectories of forceps blades between junior and senior obstetricians. STUDY DESIGN: We equipped a simulator and forceps with spatial location sensors. The head of the fetus was in an occipitoanterior location, at a "+5" station. Forceps blade trajectories were analyzed subjectively with the 3-dimensional spatial graph and objectively based on 3 points of special interest. Each obstetrician performed 4 forceps blades placements. We compared the trajectories of junior and senior obstetricians. RESULTS: For senior operators, spatial dispersion was "excellent," "very good," or "good" in 92% of cases, whereas this was the case for only 38% of junior doctors (92% vs 38%; P < .001). CONCLUSION: A new instrument has been designed to demonstrate the trajectory of forceps blades during application in a simulator. The instrument captures the difference in experience between senior and junior clinicians.
Abstract: BACKGROUND AND OBJECTIVE: In the field of drug noncompliance, we investigated an original approach that could give the prescribing physician, in collaboration with a clinical pharmacologist, an active role. The aim here is for the prescribing physician to take compliance into account so as to provide an optimised prescription (choice of molecule prescribed and its rhythm of administration) adapted to each patient. The example considered is that of oral anticoagulant treatment prescribed long-term. METHODS: In order to investigate the choice of the best molecule and treatment regimen for a given noncompliance pattern, we performed an in silico study with two oral anticoagulant agents, warfarin and acenocoumarol, each taken in one or two daily doses. Three linked models were used: the first model generated specific noncompliance patterns, the second model described the pharmacokinetics of oral anticoagulant agents and the third model summarised the pharmacokinetic-pharmacodynamic relations. RESULTS: Considering different patterns of noncompliance (including timing errors in drug intake and the phenomenon of drug holidays) and comparing warfarin with acenocoumarol, we identified different situations in which one agent (prescribed once or twice daily) could clearly minimise both the thromboembolic and haemorrhagic risks. However, for some specific noncompliance patterns, the choice of the optimal therapy should also be guided by the basal individual thromboembolic and haemorrhagic risks. CONCLUSION: Individualisation of drug therapy involves both drug dose and drug choice. In addition to the classical approach (i.e. drug level measurements, enzyme assays and even genetic sequence data), our study suggests that compliance-guided therapy may represent a potential, evolving way for the individualisation of prescriptions.
Abstract: OBJECTIVE: To quantify the accuracy of serum procalcitonin as a diagnostic test for sepsis, severe sepsis, or septic shock in adults in intensive care units or after surgery or trauma, alone and compared with C-reactive protein. To draw and compare the summary receiver operating characteristics curves for procalcitonin and C-reactive protein from the literature. DATA SOURCE: MEDLINE (keywords: procalcitonin, intensive care, sepsis, postoperative sepsis, trauma); screening of the literature. STUDY SELECTION: Meta-analysis of all 49 published studies in medical, surgical, or polyvalent intensive care units or postoperative wards. Children, medical patients, and immunocompromised patients were excluded. DATA EXTRACTION: Thirty-three studies fulfilled inclusion criteria (3,943 patients, 1,828 males, 922 females; mean age: 56.1 yrs; 1,825 patients with sepsis, severe sepsis, or septic shock; 1,545 with only systemic inflammatory response syndrome); eight studies could not be analyzed statistically. Global mortality rate was 29.3%. DATA SYNTHESIS: Global odds ratios for diagnosis of infection complicated by systemic inflammation were 15.7 for the 25 studies (2,966 patients) using procalcitonin (95% confidence interval, 9.1-27.1) and 5.4 for the 15 studies (1,322 patients) using C-reactive protein (95% confidence interval, 3.2-9.2). The summary receiver operating characteristics curve for procalcitonin was better than for C-reactive protein. In the 15 studies using both markers, the Q* value (intersection of summary receiver operating characteristics curve with the diagonal line where sensitivity equals specificity) was significantly higher for procalcitonin than for C-reactive protein (0.78 vs. 0.71, p = .02), the former test showing better accuracy. CONCLUSIONS: Procalcitonin represents a good biological diagnostic marker for sepsis, severe sepsis, or septic shock, difficult diagnoses in critically ill patients. Procalcitonin is superior to C-reactive protein. Procalcitonin should be included in diagnostic guidelines for sepsis and in clinical practice in intensive care units.
Abstract: We performed a meta-analysis of all published studies relating intratumoural microvessel density (MVD) (45 studies) or vascular endothelial growth factor (VEGF) expression (27 studies), both reflecting angiogenesis, to relapse free (RFS) and overall survival (OS) in colorectal cancer (CRC). For each study, MVD impact was measured by risk ratio between the two survival distributions with median MVD as cutoff. Eleven studies did not mention survival data or fit inclusion criteria, six were multiple publications of same series, leaving 32 independent studies for MVD (3496 patients) and 18 for VEGF (2050 patients). Microvessel density was assessed by immunohistochemistry, using antibodies against factor VIII (16 studies), CD31 (10 studies) or CD34 (seven studies). Vascular endothelial growth factor expression was mostly assessed by immunohistochemistry. Statistics were performed for MVD in 22 studies (the others lacking survival statistics) including nine studies (n = 957) for RFS and 18 for OS (n = 2383) and for VEGF in 17 studies, including nine studies for RFS (n = 1064) and 10 for OS (n = 1301). High MVD significantly predicted poor RFS (RR = 2.32 95% CI: 1.39-3.90; P < 0.001) and OS (RR = 1.44; 95% CI: 1.08-1.92; P = 0.01). Using CD31 or CD34, MVD was inversely related to survival, whereas it was not using factor VIII. Vascular endothelial growth factor expression significantly predicted poor RFS (RR = 2.84; 95% CI: 1.95-4.16) and OS (RR=1.65; 95% CI: 1.27-2.14). To strengthen our findings, future prospective studies should explore the relation between MVD or VEGF expression and survival or response to therapy (e.g. antiangiogenic therapy). Assessment of these angiogenic markers should be better standardised in future studies.
Abstract: BACKGROUND AND OBJECTIVES: Clinical trials increasingly use results of diagnostic tests as surrogate outcomes. Our objective was to answer the following questions: (1) is the parameter measured by the reference standard a valid surrogate? (2) How does the tests accuracy influence the estimate of the treatment benefit on surrogate? (3) Is it possible to correct the measured treatment effect given by results of inaccurate tests? METHODS AND SETTING: We reviewed the literature on asymptomatic deep venous thrombosis (DVT), detected by the reference standard and other imaging techniques, as surrogate for venous thromboembolism. The influence of test inaccuracy on the measurement of treatment benefit was calculated as a function of the patient baseline risk, the treatment effect model, and test performances. RESULTS: We show that: (1) asymptomatic DVT is correlated with clinical outcomes but is yet to be established as a surrogate; (2) inaccurate diagnostic test underestimates the treatment effect on surrogate; (3) the prevalence of the disease, the treatment effect model, and the accuracy of the test and the reference standard used to evaluate it need to be known to correct this underestimation. CONCLUSION: Even when the surrogate end point is valid, without a reliable study of the diagnostic test we cannot quantify the true treatment effect.
Abstract: Since the early 1980s many studies showed a gap between available evidence and medical practice. They were designed to assess the real impact of randomized clinical trials on the practice of medicine. Their results substantiated a knowledge translation problem. However, they were qualitative findings, i.e. a gap exists or not, although the problem is quantitative (how large is the gap?) and has several components that should be documented according to the objective of the study. In this article, we explored the components and the various contexts in which the measure of the distance between practice and knowledge is considered. All these features should be taken into account for a more accurate and relevant assessment of the distance.
Abstract: OBJECTIVE: The International Prostatic Symptom Score (IPSS) evaluates urinary disorder symptoms frequently associated with benign prostatic obstruction, but does not take into account the bothersomeness they induce. The Symptom Problem Index (SPI) evaluates the degree of discomfort associated with each question on the IPSS. Our objective was to explore the relationships between these two rating scales. METHODS: The IPSS and SPI self-administered scores were administrated to a cohort of 907 patients presenting with LUTS suggestive of BPO (Benign Prostatic Obstruction), for which 722 patients were evaluable. This diagnosis was made by GP (General Practitioner) in the 3-month period before their inclusion in the study. The correlation between SPI and IPSS was investigated and each symptom was classified according to its frequency and according to the bothersomeness it induced. The degree of bothersomeness associated with each IPSS symptom was evaluated and quantified based on quadratic function estimates. RESULTS: The mean IPSS score was 12.6+/-6.4, the mean SPI score was 12.2+/-6.5. The correlation coefficient between the IPSS and SPI scores was 0.70; the scores from the 2 rating scales showed a very high variability. On a 0-100% scale, where 100% represents a maximum bothersomeness, the induced bothersomeness ranged from 0 to 22.6% depending on the 7 symptoms. CONCLUSIONS: The two questionnaires do not collect the same information. The extent of variability between the two scales confirms that one scale cannot be replaced by the other. Considering the importance of bothersomeness associated with lower urinary tract symptoms for the therapy decision, the joint use of the IPSS and SPI seems appropriate.
Abstract: The complexity of pathophysiological mechanisms is beyond the capabilities of traditional approaches. Many of the decision-making problems in public health, such as initiating mass screening, are complex. Progress in genomics and proteomics, and the resulting extraordinary increase in knowledge with regard to interactions between gene expression, the environment and behaviour, the customisation of risk factors and the need to combine therapies that individually have minimal though well documented efficacy, has led doctors to raise new questions: how to optimise choice and the application of therapeutic strategies at the individual rather than the group level, while taking into account all the available evidence? This is essentially a problem of complexity with dimensions similar to the previous ones: multiple parameters with nonlinear relationships between them, varying time scales that cannot be ignored etc. Numerical modelling and simulation (in silico investigations) have the potential to meet these challenges. Such approaches are considered in drug innovation and development. They require a multidisciplinary approach, and this will involve modification of the way research in pharmacology is conducted.
Abstract: OBJECTIVE: Consideration of absolute risk has been recommended for making decisions concerning preventive treatment in hypertension. We performed simulations to estimate the benefit of antihypertensive therapy over a life-time. METHODOLOGY: The rate of nonfatal and fatal events of untreated hypertensives in the US population were estimated using data from Individual Data ANalysis of Antihypertensive drug intervention trials (INDANA; a meta-analysis on individual data in hypertension) and specific cause of death from national statistics. Disease-free survival curves until all patients have died were built using the "life-table" method. The treatment effect estimated from INDANA was applied to this curve to obtain the disease-free survival curve of the life-long treated population. Gains in event-free life expectancy (GLE) were estimated from survival curves. A sensitivity analysis was performed to assess the impact of possible death misclassifications. RESULTS: For a 40-year-old man, the gain in life expectancy without stroke and major cardiovascular events were 27 and 32 months, respectively, and were more substantial than those without coronary disease (19 months). The GLE decreased slowly with increasing age at the beginning of treatment, whereas short-term absolute risk reductions increase sharply with age. CONCLUSIONS: Policies based on the selection of patients to treat according to absolute benefit do not maximize the GLE compared with strategies that treat low-risk patients.
Abstract: BACKGROUND: Cooled-tip RFA (cRFA) and conventional 8-mm-tip catheters were found to be more effective and as safe as conventional 4-mm-tip catheters for atrial flutter (AFL) radiofrequency ablation (RFA), facilitating the rapid achievement of bi-directional isthmus block (BIB), but studies comparing cRFA and 8-mm-tip catheters are not randomized or results are discussed. Thus, we performed a meta-analysis of available randomized trials to evaluate the effectiveness in terms of primary success and procedure parameters. METHODS: Reports of trials were identified through a Medline, Embase, Current Contents, Cardline, and an extensive bibliography search. Trials that met the following criteria were included: (1) prospective, randomized, controlled, and open trials; (2) patients assigned to an 8-mm-tip or a cRFA catheter for AFL RFA; (3) endpoints events related to primary success rate (BIB achievement), and procedure parameters (number of RF applications, x-ray exposure and ablation duration). RESULTS: Seven trials met the inclusion criteria. They included 603 patients with established AFL randomized to an 8-mm-tip or cRFA catheter group. Comparing 8-mm groups with cRFA groups, the meta-analysis showed similar BIB achievement relative risk (RR) 0.96, 95% confidence interval (CI): 0.92 to 1.01, (P = 0.13); total RF application time weighted mean difference (WMD) 0.88, 95% CI: -0.36 to 2.12, (P = 0.16); duration of x-ray exposure (min) (WMD = 1.07, 95% CI: -0.81 to 0.295, (P = 0.26); ablation procedure duration (min) (WMD = 0.68, 95% CI: -3.37 to 4.73; P = 0.74). CONCLUSION: The present meta-analysis confirms that cooled-tip and large-tip catheters are equally efficient for cavotricuspid isthmus ablation with both similar primary success rates and procedure parameters.
Abstract: OBJECTIVES: To correlate changes of cranial vault measurements of an adult population during the aging process with brain size using the maximum width of the third ventricle in the axial AC-PC plane. MATERIALS AND METHODS: Prospective study of 126 adult subjects (range: 20 to 80 years) with normal brain MRI and without history of neuropsychiatric disorder. MEASUREMENTS INCLUDED: Cranial vault (Maximum length: Glabella-Opisthocranion, Maximum width: euryon-euryon, and maximum height: Basion-Vertex) measurements and maximum width of the third ventricle in the A C-PC plane. RESULTS: Vault measurements (length, width, high) were similar for every age group, irrespective of gender. The variability of cranial vault measurements between individuals was low (<1 cm). Cranial vault measurements were larger for men, but this was not significant when adjusted for body height Comparatively, a gradual widening of the third ventricle, with an exponential behavior, was observed with advancing age. CONCLUSION: Our results indicate that cranial vault measurements are stable over time (between 20-80 years) comparatively to brain atrophy with advancing age. The low variability of cranial vault measurements and their stability over time should be taken into account during segmentation and normalization of brain parenchymal structures.
Abstract: OBJECTIVE: This study was undertaken to investigate the reliability of transvaginal assessment of fetal head station by using a newly designed birth simulator. STUDY DESIGN: This prospective study involved 32 residents and 25 attending physicians. Each operator was given all 11 possible fetal stations in random order. A fetal head mannequin was placed in 1 of the 11 American College of Obstetricians and Gynecologists (ACOG) stations (-5 to +5) in a birth simulator equipped with real-time miniaturized sensor. The operator then determined head position clinically using the ACOG classification. Head position was described as: (1) "engaged" or "nonengaged" (engagement code); (2) "high," "mid," "low," or "outlet" (group code); and (3) according to the 11 ACOG ischial spine stations (numerical code). Errors were defined as differences between the stations given by the sensor and by the operator. We determined the error rates for the 3 codes. RESULTS: "Numerical" errors occurred in 50% to 88% of cases for residents and in 36% to 80% of cases for attending physicians, depending on the position. The mean "group" error was 30% (95% CI 25%-35%) for residents and 34% (95% CI 27%-41%) for attending physicians. In most cases (87.5% for residents and 66.8% for attending physicians) of misdiagnosis of "high" station, the "mid" station was retained. Residents and attending physicians made an average of 12% of "engagement" errors, equally distributed between false diagnosis of engagement and nonengagement. CONCLUSION: Our results show that transvaginal assessment of fetal head station is poorly reliable, meaning clinical training should be promoted. The choice not to perform vaginal delivery when the fetus is in the "mid" position strongly decreases the risk of applying instruments on an undiagnosed "high" station. Conversely, obstetricians who perform only "low" operative vaginal deliveries also deliver unrecognized "mid" station fetuses. Therefore, residency programs should offer training in "mid" pelvic operative vaginal deliveries. Birth simulators could be used in training programs.
Abstract: BACKGROUND: A wide gap continues to exist between available therapeutic research results and physician's prescribing. Numerous explanations account for this gap, but one central reason is the difficulty in transferring comprehensive research information to practicing clinicians. This problem arises from information overload and the growing complexity of research findings. We propose a multistep process that can be used to develop systems to bridge this information/prescription gap. The steps include: comprehensively collecting and summarizing clinical trial reports, scoring and ranking these according to their level of evidence, exploring and synthesizing the data using meta-analyses, summarizing these results, representing them in an easily understandable form, and transmitting the overview findings to prescribers at the time they need them. DISCUSSION: This ambitious endeavor is needed to ensure that prescribers have access to pertinent research results for use in their prescription decisions. We demonstrate in this article that there are no theoretical or technical obstacles to make the proposed system workable.
Abstract: Understanding the mechanisms and the time and spatial evolution of penumbra following an ischemic stroke is crucially important for developing therapeutics aimed at preventing this area from evolving towards infarction. To help in integrating the available data, we decided to build a formal model. We first collected and categorised the major available evidence from animal models and human observations and summarized this knowledge in a flow-chart with the potential key components of an evolving stroke. Components were grouped in ten sub-models that could be modelled and tested independently: the sub-models of tissue reactions, ionic movements, oedema development, glutamate excitotoxicity, spreading depression, NO synthesis, inflammation, necrosis, apoptosis, and reperfusion. Then, we figured out markers, identified mediators and chose the level of complexity to model these sub-models. We first applied this integrative approach to build a model based on cytotoxic oedema development following a stroke. Although this model includes only three sub-models and would need to integrate more mechanisms in each of these sub-models, the characteristics and the time and spatial evolution of penumbra obtained by simulation are qualitatively and, to some extent, quantitatively consistent with those observed using medical imaging after a permanent occlusion or after an occlusion followed by a reperfusion.
Abstract: OBJECTIVE: To examine the evidence for efficacy of surgery in the treatment of intractable epilepsy. METHOD: Meta-analysis of randomized clinical trials. RESULTS: One randomized clinical trial (n=80) and 3 observational studies are available. INTERPRETATION: Compared to medical treatment, the surgery increases the proportion of patients who were free of seizure impairing awareness at 1 year (relative risk: 7.67, IC 95% 2.5 Ã 23.51) CONCLUSION: The available evidence about the clinical efficacy of surgery for patient with intractable epilepsies is limited to an unique open randomized clinical trial, that enrolled patient in a single centre, without concealment of the randomization and with a partially subjective primary endpoint. However, this trial shows a substantial effect corresponding to a 8 fold increase in the number of patient without seizure at 1 year. The informational situation will be better when the results of a currently ongoing trial will be available.
Abstract: BACKGROUND: The benefit-to-risk ratio of vitamin K antagonists (VKA), relative to active comparators, especially low-molecular-weight heparins (LMWH), for preventing venous thromboembolism in patients undergoing major orthopedic surgery is debated. OBJECTIVES: We performed a meta-analysis of all randomized trials in orthopedic surgery comparing adjusted doses of VKA to control treatments. PATIENTS AND METHODS: An exhaustive literature search, both manual and computer-assisted, was performed. Studies were selected on the basis of randomization procedure (VKA vs. a control group). At least one of the following outcome measures was to be evaluated: deep vein thrombosis (DVT), pulmonary embolism (PE), death, major hemorrhage or wound hematoma. Four reviewers assessed each article to determine eligibility for inclusion and outcome measures. RESULTS: VKAs were more effective than placebo or no treatment in reducing DVT [567 patients, relative risk (RR) = 0.56, 95% confidence interval (CI) 0.37, 0.84, P < 0.01] and clinical PE (651 patients, RR = 0.23, 95% CI 0.09, 0.59, P < 0.01). These results were obtained at the cost of a higher rate of wound hematoma (162 patients, RR = 2.91, 95% CI 1.09, 7.75, P = 0.03). VKAs were also more effective than intermittent pneumatic compression (534 patients, RR = 0.46, 95% CI 0.25, 0.82, P = 0.009) in preventing proximal DVT. In contrast, VKAs were less effective than LMWH in preventing total DVT and proximal DVT (9822 patients, RR = 1.51, 95% CI 1.27, 1.79, P < 0.001; and 6131 patients, RR = 1.51, 95% CI 1.04, 2.17, P = 0.028, respectively). The differences between VKA and LMWH in major hemorrhage and wound hematoma were not significant. CONCLUSIONS: In patients undergoing major orthopedic surgery, VKAs are less effective than LMWH, without any significant difference in the bleeding risk.
Abstract: Evaluation of the accuracy of ultrasound has yielded heterogeneous results. Our objective was to summarize the evidence on the accuracy of ultrasound compared to venography in asymptomatic patients, taking into account the variation due to threshold differences. Searches of journal table of contents, computer databases (Medline, Embase, Biomed, Cochrane) and conference proceedings were performed. A study was eligible if it prospectively compared ultrasound to venography for the diagnosis of DVT in asymptomatic patients. Data of studies selected for inclusion were extracted independently by two authors. High quality studies with consecutive patient enrollment, blind evaluation of the two techniques, and absence of verification bias are summarized as Level 1, while those not fulfilling one or more of these criteria are considered Level 2. Original study authors were contacted to confirm accuracy and to provide missing data. A pooled estimate of the accuracy of ultrasound was obtained according to the method of Moses and coworkers. This method gives a summary diagnostic odds ratio (DOR). The DOR is a single indicator of test performance. It varies between 0 and infinity and exceeds 1, only when ultrasound is more often positive in patients with DVT relative to those without DVT. Higher DOR indicates better discriminatory test performance. Thirty one studies were rated as potentially unbiased and graded as Level 1. The mean prevalence of DVT as determined by venography was 22%. In Level 1 studies, the odds of positive ultrasound in proximal veins was 379 times higher (95% confidence limits 65, 2,200) and in distal veins 32 times higher (7.5, 135) among patients with DVT than those without. Our results suggest that, particularly for proximal veins, ultrasound is accurate for the diagnosis of DVT in asymptomatic postoperative orthopedic patients. More research is needed in other clinical settings.
Abstract: We performed a meta-analysis of all 87 published studies linking intratumoral microvessel density (MVD), reflecting angiogenesis, to relapse-free survival (RFS) and overall survival (OS). With median MVD as cutoff, MVD impact was measured by risk ratio (RR) between the two survival distributions. Seventeen studies did not mention survival data or fit inclusion criteria. Twenty-two were multiple publications of the same series, leaving 43 independent studies (8936 patients). MVD was assessed by immunohistochemistry, using antibodies against factor VIII (27 studies; n = 5262), CD31 (10 studies; n = 2296), or CD34 (8 studies; n = 1726). MVD might be a better prognostic factor when assessed by CD31 or CD34 versus factor VIII (P = 0.11). For RFS, statistical calculations were performed in 25 studies (6501 patients). High MVD significantly predicted poor survival [RR = 1.54 for RFS and OS with the same 95% confidence interval (CI), 1.29-1.84]. Twenty-two studies analyzed separately lymph node-negative patients (n = 3580), for whom predictors of poor survival are requested. This latter meta-analysis included 15 studies for RFS (2727 patients) and 11 for OS (1926 patients). High MVD significantly predicted poor survival [RR = 1.99 for RFS (95% CI, 1.33-2.98) and RR = 1.54 for OS (95% CI, 1.01-2.33)]. Between-study variations could result from patient selection criteria, techniques to stain and count microvessels, and cutoff selection. MVD was a significant although weak prognostic factor in women with breast cancer. Standardization of MVD assessment is needed.
Abstract: The simulation of therapeutic models and clinical trial simulation have recently attracted attention as emerging techniques for developing new active molecules and the exploration of possible clinical trial results. Such approaches have benefited from fundamental progress in the development of 'in silico' models, as well as progress in nonlinear mixed-effect pharmacokinetic-pharmacodynamic models. Mixing the two approaches allows simulation of 'virtual' patients, who receive virtual treatments or placebo. These have various uses, such as proof of concept, decision analysis or experimental design optimisation. Also, the effect of departures from protocol on clinical trial results can easily be evaluated by the use of simulation. This technique is now implemented by the pharmaceutical industry for optimising phase II and III experimental designs when a good biomarker or a clinical outcome model is available, but the use of an in silico therapeutic model as a proof of concept is only just beginning. In order to see such methodologies used more widely in drug development, multidisciplinary efforts need to be initiated, new modelling and simulation tools developed, and sound modelling and simulation practice documents need to be adopted. A reduction in the number of failed clinical development projects, the number of negative phase II and III clinical trials, or in just their cost and duration, are among the expected benefits of modelling and simulation in clinical drug development.
Abstract: OBJECTIVE: To determine factors predictive of mortality in patients undergoing emergency mitral valve surgery in the setting of severe post-infarction regurgitation. METHODS: Patients admitted for an acute myocardial infarction who required urgent mitral valve surgery for severe regurgitation were studied. Factors predictive of outcome were analysed. RESULTS: Fifty-five consecutive patients (mean 65+/-10 years, 37 males) were included. The infarct was inferior in 31 patients, posterior in 10, anterior in 9 and lateral in 5. Thirty-four patients (62%) were in Killip class IV. Peroperative findings confirmed total papillary muscle rupture in 25 patients (posteromedial in 21, anterolateral in 4), and partial rupture in 12 patients (posteromedial in 10, anterolateral in 2). Papillary muscle dysfunction without rupture was responsible for regurgitation in 18 patients (posteromedial in 15, anterolateral in 3). The mitral valve was replaced by a prosthesis in all but 4 patients, who had valvuloplasty. Coronary angiography was done in 32 patients, of whom 18 underwent concomitant coronary artery bypass grafting and 2 balloon angioplasty. Surgery was performed on average 7 days after infarction. Thirteen patients (24%) died during the perioperative period. Absence of coronary revascularisation was significantly associated with increased perioperative mortality (34% vs. 9%, P = 0.02). Of the 42 surviving patients, there were 5 deaths during a mean follow-up of 4.0+/-3.7 years. CONCLUSION: In patients with acute post-infarction mitral regurgitation, perioperative mortality is high, but can be improved with concomitant CABG in addition to valve surgery. Long-term outcome of survivors is favourable.
Abstract: AIMS: For ethical and economic reasons, interim analysis of phase III clinical trials is essential. This study was conducted to compare the efficiency of two interim analysis procedures, which could be used to allow early termination of a clinical trial. METHODS: We made a post hoc application of two interim analysis methods (Lan & DeMets with O'Brien-Flemming modification, and the triangular test according to Whitehead) by using individual patient data from four published placebo-controlled survival trials. We determined the date the trial would have been stopped had each method been used, and we estimated consequent results in terms of events and patient numbers included in the trial, the duration of the trial, and on treatment effect. RESULTS: The triangular test provided the lowest number of events required to reach a conclusion of the trials while providing an accurate estimate of experimental treatment effects. The triangular test thus indicated the smallest number of patients that would have been enrolled, and the shortest trial duration. The difference between the methods was most important with a detrimental effect of experimental treatment: the number of required events was reduced by 75% and the trial duration was shortened by 48% with the triangular test compared to the Lan & DeMets method. CONCLUSIONS: Stopping a trial early must depend on the clinical context. It is most important to stop a placebo-controlled trial as soon as possible when the experimental treatment can be shown deleterious. In such a situation the triangular test is more appropriate than the Lan & DeMets method. When a treatment effect is no different from, or better than, placebo the triangular test is also superior but the importance of premature termination of the trial in such cases has to be balanced against the inevitable reduction of information that the trial can provide.
Abstract: In the current paper, we provide recommendations for the assessment of deep vein thromboses for the purpose of therapeutic trials evaluating antithrombotic drugs in the prevention of deep venous thrombosis. We have reviewed recently published articles on diagnostic and therapeutic studies, and we have evaluated methods of assessments. Ascending venography has been considered as the reference test for the confirmation of DVT. A roentgenographic image is subsequently available for review and allows classification by blinded, objective observers. However, venography poses substantial clinical and methodological limitations, particularly in the setting of systematic screening for all patients enrolled in a randomized clinical trial. Compression ultrasonography may replace venography for systematic screening of DVT in clinical trials, provided that specific methodological details are specified in the protocol and are fulfilled to ensure high and comparable sensitivity and specificity from all participating centers. This non-invasive technique has virtually no contraindications, and therefore more patients can be enrolled and evaluated. Furthermore, the compression ultrasonograph can be videotaped for central reading. Compression ultrasonography has already been adopted as the principal method for evaluating DVT in several ongoing large scale prevention trials with the approval of major drug agencies.
Abstract: BACKGROUND: Intravenous thrombolytic therapy is the standard care for patients with acute myocardial infarction, based upon its widespread availability and ability to reduce patient mortality well demonstrated in randomised trials. Despite its proven efficacy, thrombolytic therapy has limitations. Many patients are ineligible for treatment with thrombolytics. Of those given thrombolytic therapy, 10 to 15 percent have persistent occlusion or reocclusion of the infarct-related artery. Consequently, primary angioplasty (primary PTCA) has been advocated as a better treatment of myocardial infarction. OBJECTIVES: To determine whether primary coronary angioplasty is superior to thrombolytic therapy for the treatment of patients with acute myocardial infarction. SEARCH STRATEGY: Electronic search of The Cochrane Library (1998; Issue 2). MEDLINE (to January 1998); references from reviews, trials and previously published meta-analyses; and experts. Date of most recent searches January 1998. SELECTION CRITERIA: All unconfounded, randomised controlled trials comparing primary angioplasty against intravenous thrombolysis in patients with acute myocardial infarction DATA COLLECTION AND ANALYSIS: At least two independent reviewers abstracted data on morbidity and mortality and trial characteristics. The following outcomes were assessed: total mortality at the end of the study, reinfarction, stroke of any type, composite endpoint of death and reinfarction, recurrent ischemia, severe bleeding and coronary artery bypass grafting. MAIN RESULTS: Ten trials including 2573 subjects were identified. Compared to thrombolytic therapy, primary angioplasty was associated with a significant reduction in short-term mortality at the end of the studies (relative reduction in risk RRR = 32% 95%CI = 5%;50%). Similar reductions were observed for the rate of reinfarction (RRR = 52%, 95%CI = 30%;67%), recurrent ischemia (RRR = 54%; 95%CI = 39%,66%) and for the combined criteria death or reinfarction (RRR = 46%; 95%CI=30%;58%). The frequency of strokes of any cause was significantly decreased by 66% (95%CI=28%;84%). No significant difference was observed for the incidence of major bleeding (relative risk RR =1.18, 95%CI = 0.73;1.90) but the confidence interval was large.The superiority of the primary angioplasty over thrombolysis in terms of the composite endpoint (mortality and reinfarction) was less with accelerated t-PA (RR=0.70, 95%CI=0.51;0.97) than with streptokinase (RR=0.30, 95%CI=0.17;0.53).The biggest and most recent trial, Gusto 2B (GUSTO-2B 97), which involved general as well as highly specialised centres, obtained less favorable results. AUTHORS' CONCLUSIONS: This meta-analysis suggests that angioplasty provides a short-term clinical advantage over thrombolysis which may not be sustained. Primary angioplasty when available promptly at experienced centres, may be considered the preferred strategy for myocardial reperfusion. In most situations, however, optimal thrombolytic therapy should still be regarded as an excellent reperfusion strategy.
Abstract: BACKGROUND: Intravenous thrombolytic therapy is the standard care for patients with acute myocardial infarction, based upon its widespread availability and ability to reduce patient mortality well demonstrated in randomised trials. Despite its proven efficacy, thrombolytic therapy has limitations. Many patients are ineligible for treatment with thrombolytics. Of those given thrombolytic therapy, 10 to 15 percent have persistent occlusion or reocclusion of the infarct-related artery. Consequently, primary angioplasty (primary PTCA) has been advocated as a better treatment of myocardial infarction. OBJECTIVES: To determine whether primary coronary angioplasty is superior to thrombolytic therapy for the treatment of patients with acute myocardial infarction. SEARCH STRATEGY: Electronic search of The Cochrane Library (1998; Issue 2). MEDLINE (to January 1998); references from reviews, trials and previously published meta-analyses; and experts. Date of most recent searches January 1998. SELECTION CRITERIA: All unconfounded, randomised controlled trials comparing primary angioplasty against intravenous thrombolysis in patients with acute myocardial infarction DATA COLLECTION AND ANALYSIS: At least two independent reviewers abstracted data on morbidity and mortality and trial characteristics. The following outcomes were assessed: total mortality at the end of the study, reinfarction, stroke of any type, composite endpoint of death and reinfarction, recurrent ischemia, severe bleeding and coronary artery bypass grafting. MAIN RESULTS: Ten trials including 2573 subjects were identified. Compared to thrombolytic therapy, primary angioplasty was associated with a significant reduction in short-term mortality at the end of the studies (relative reduction in risk RRR = 32% 95%CI = 5%;50%). Similar reductions were observed for the rate of reinfarction (RRR = 52%, 95%CI = 30%;67%), recurrent ischemia (RRR = 54%; 95%CI = 39%,66%) and for the combined criteria death or reinfarction (RRR = 46%; 95%CI=30%;58%). The frequency of strokes of any cause was significantly decreased by 66% (95%CI=28%;84%). No significant difference was observed for the incidence of major bleeding (relative risk RR =1.18, 95%CI = 0.73;1.90) but the confidence interval was large.The superiority of the primary angioplasty over thrombolysis in terms of the composite endpoint (mortality and reinfarction) was less with accelerated t-PA (RR=0.70, 95%CI=0.51;0.97) than with streptokinase (RR=0.30, 95%CI=0.17;0.53).The biggest and most recent trial, Gusto 2B (GUSTO-2B 97), which involved general as well as highly specialised centres, obtained less favorable results. REVIEWER'S CONCLUSIONS: This meta-analysis suggests that angioplasty provides a short-term clinical advantage over thrombolysis which may not be sustained. Primary angioplasty when available promptly at experienced centres, may be considered the preferred strategy for myocardial reperfusion. In most situations, however, optimal thrombolytic therapy should still be regarded as an excellent reperfusion strategy.
Abstract: The absolute benefit (AB) is extensively used to summarize the results of clinical trials. As the AB depends directly on the patient's baseline risk, therapeutic decisions based on AB tend to favor patients at high risk. To evaluate the consequences of this decision's procedure for life-long therapy, we compare the AB with the gain in event-free life expectancy in a simulated hypertensive population. Our results show that the AB goes through a maximum and then declines as the duration of treatment increases. The amplitude of the variation of AB is independent of the baseline risks but the maximum is reached more quickly in the high-risk patients. Considering the gain in event-free life expectancy, low-risk patients benefit more than high-risk patients do, at the expense of a longer treatment exposure. The interpretation of the AB changes depending on follow-up.
Abstract: Bringing all available evidence on therapy efficacy to users is a necessary step in the evidence-based medicine paradigm. Today, the needs of physicians in medical information, including therapeutic information, are not met. Further, the information reaching the doctors is rarely consistent with the available evidence. The growth rate of emerging evidence and its increasing complexity make the doctors unable to cope with it within the current medical information system. So, there is a real need to sort out a new way for transferring therapeutic information to doctors and patients. We conceived a new paradigm and designed an Internet process based on it by which unbiased evidence is brought to doctors in such a format that it can be accessed and used during the visit.
Abstract: In a narrow meaning, responders to a therapy are all those who will react as expected following the administration of this therapy. However, a wider definition is worth considering: all those for whom the administration of the therapy will be beneficial. Innovative therapies are increasingly expensive and hazardous, and limiting prescriptions to responders is both economically and ethically compulsory. The theoretical basis for such an approach exists. The process of defining the profile of responders consists of identifying the characteristics of the patients that interact with the size of the effect and integrating them quantitatively in a predictive model. The effect model, which is the relation between the risks of the event with and without the treatment, can be used for the prediction. It can integrate interactions of the efficacy with risk factors and/or genes. The data to be used to achieve both the identification of the interactions and the building of the predictive model are those from the studied population, the set of patients enrolled in clinical trials. Hence, the process of defining the therapy is an extrapolation from the studied population. To carry out the extrapolation process one can use various available techniques, of which none fully fits the purpose. No method is currently both fully adequate and validated. Finally, the predictive models, which we need to identify responders, do not exist in practice. Fortunately, new research approaches have been developed recently.
Abstract: OBJECTIVE: To assess the structural and symptomatic efficacy of oral glucosamine sulfate and chondroitin sulfate in knee osteoarthritis through independent meta-analyses of their effects on joint space narrowing, Lequesne Index, Western Ontario MacMaster University Osteoarthritis Index (WOMAC), visual analog scale for pain, mobility, safety, and response to treatment. METHODS: An exhaustive systematic research of randomized, placebo-controlled clinical trials published or performed between January 1980 and March 2002 that assessed the efficacy of oral glucosamine or chondroitin on gonarthrosis was performed using MEDLINE, PREMEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Current Contents, BIOSIS Previews, HealthSTAR, EBM Reviews, manual review of the literature and congressional abstracts, and direct contact with the authors and manufacturers of glucosamine and chondroitin. Inclusion, quality scoring, and data abstraction were performed systematically by 2 independent reviewers who were blinded to sources and authors. Conservative approaches were used for clear assessment of potential efficacy. RESULTS: Our results demonstrated a highly significant efficacy of glucosamine on all outcomes, including joint space narrowing and WOMAC. Chondroitin was found to be effective on Lequesne Index, visual analog scale pain, mobility, and responding status. Safety was excellent for both compounds. CONCLUSIONS: Our study demonstrates the structural efficacy of glucosamine and indistinguishable symptomatic efficacies for both compounds. Regarding the relatively sparse data on glucosamine and joint space narrowing and the absence of data on structural effects of chondroitin, further studies are needed to investigate the relationship among time, dose, patient baseline characteristics, and structural efficacy for an accurate, disease-modifying characterization of these 2 compounds.
Abstract: OBJECTIVES: This meta-analysis compared amiodarone with placebo and class Ic drugs for the cardioversion of recent-onset atrial fibrillation (AF), defined as lasting less than seven days. BACKGROUND: Despite the lack of trials that support its efficacy convincingly, amiodarone is widely used for conversion of recent-onset AF. METHODS: We searched Medline and EMBASE databases, as well as the Cochrane Controlled Trials Register for randomized trials on recent-onset AF comparing amiodarone to placebo or class Ic drugs. Data were combined according to a fixed effect model. The primary end point was the rate of conversion at 24 h. To study time-dependency of the drugs, efficacy at 1 to 2 h, 3 to 5 h, 6 to 8 h, and at 24 h was analyzed. RESULTS: We found six studies randomizing amiodarone versus placebo (595 patients) and seven studies versus class Ic drugs (579 patients). There was no significant difference between amiodarone and placebo at 1 to 2 h, but significant efficacy was found after 6 to 8 h (relative risk [RR] 1.23, p = 0.022) and at 24 h (RR 1.44, p < 0.001). Efficacy with amiodarone was inferior to class Ic drugs for up to 8 h (RR 0.67, p < 0.001) but no difference was seen at 24 h (RR 0.95, p = 0.50). There were no major adverse effects. CONCLUSIONS: Amiodarone is superior to placebo for cardioversion of AF, and even though the onset of conversion is delayed, its efficacy is similar at 24 h compared with class Ic drugs. These results favor amiodarone as a reasonable alternative for patients with recent AF in whom class Ic and other, more rapidly acting antiarrhythmic drugs cannot be used.
Abstract: The authors conducted a randomized trial in Geneva, Switzerland, to assess whether response rates to a mailed survey could be increased by printing the questionnaire on green paper. The authors also conducted a meta-analysis of 10 experimental studies that tested the effect of colored questionnaires on response rates. The randomized trial showed no effect (relative risk of responding [RR] = 1.00). The meta-analysis showed that mailing questionnaires on pink paper increased response rates by 12% (RR = 1.12, 95% confidence interval = 1.01 to 1.25, p = 0.04). Other colors had no statistically significant effect (blue: RR = 1.03, p = 0.49; green: RR = 1.02, p = 0.23; yellow: RR = 0.96, p = 0.30). Overall, using colored instead of white paper had no effect (RR = 1.02, p = 0.17). Thus, printing questionnaires on colored paper does not substantially increase response rates in surveys, except for pink paper.
Abstract: BACKGROUND: Despite the available evidence from randomized clinical trials, beta-blockers are often not used optimally in patients with congestive heart failure (CHF). This meta-analysis aims at providing a precise and quantitative estimate of the benefit and risks of long-term bisoprolol on major clinical events in patients with CHF, both overall and in selected subgroups. This may help clinicians in their decisions as to whether to prescribe bisoprolol for their individual patients. METHODS: Meta-analysis was performed of results from the 2 randomized, controlled clinical studies in which bisoprolol was compared with placebo (Cardiac Insufficiency Bisoprolol Study [CIBIS and CIBIS II]), which included 3288 patients with proven CHF. The main outcomes were total death, cardiovascular death, sudden death, hospitalization for heart failure, and myocardial infarction. RESULTS: A highly significant 29.3% relative reduction of death (17%, 40%; P =.00003) was observed, as well as significant risk reduction in cardiovascular death and sudden death in favor of bisoprolol. Also, a highly significant relative reduction of 18.4% (25%, 11%; P =.00001) in hospital admission or death was observed. A similar relative reduction of death was consistently observed in selected subgroups of patients. CONCLUSIONS: Bisoprolol prevents major cardiovascular events in patients with CHF with a high benefit-to-risk ratio and can be recommended for these patients.
Abstract: BACKGROUND: The "integrated safety report" of the drug registration files submitted to health authorities usually summarizes the rates of adverse events observed for a new drug, placebo or active control drugs by pooling the safety data across the trials. Pooling consists of adding the numbers of events observed in a given treatment group across the trials and dividing the results by the total number of patients included in this group. Because it considers treatment groups rather than studies, pooling ignores validity of the comparisons and is subject to a particular kind of bias, termed "Simpson's paradox." In contrast, meta-analysis and other stratified analyses are less susceptible to bias. METHODS: We use a hypothetical, but not atypical, application to demonstrate that the results of a meta-analysis can differ greatly from those obtained by pooling the same data. In our hypothetical model, a new drug is compared to 1) a placebo in 4 relatively small trials in patients at high risk for a certain adverse event and 2) an active reference drug in 2 larger trials of patients at low risk for this event. RESULTS: Using meta-analysis, the relative risk of experiencing the adverse event with the new drug was 1.78 (95% confidence interval [1.02; 3.12]) compared to placebo and 2.20 [0.76; 6.32] compared to active control. By pooling the data, the results were, respectively, 1.00 [0.59; 1.70] and 5.20 [2.07; 13.08]. CONCLUSIONS: Because these findings could mislead health authorities and doctors, regulatory agencies should require meta-analyses or stratified analyses of safety data in drug registration files.
Abstract: The coding of information in the computer representation of clinical trials is essential both for the rationalisation of the activities involved in the production of therapeutic information for evidence-based decision support and for the integration of the messages produced by these activities with clinical information and electronic patient record systems. There is no standard coding system available, however, so building on existing evaluations, we performed a simple semi-quantitative evaluation of ICD-10, CDAM, MEDDRA, MESH, READ, SNOMED and UMLS to provide objective criteria for the choice of a coding system. Inclusion and exclusion criteria for four clinical trials recorded in TriSum constituted the corpus of evaluation texts. Criteria included coding coverage, size, integration and language coverage. The results of the comparison lead us to choose SNOMED as the most appropriate coding system for our needs. The absence of a European Medical Language System project is observed, as is the need for combinatorial as opposed to enumerative systems.
Abstract: In the treatment of acute ischemic stroke most of the clinical trials have failed, contrasting with promising results in the preclinical stages. This continuing discrepancy suggests some misconceptions in the understanding of acute ischemic stroke. One possible method for identifying the shortcomings of present-day approaches is to integrate all the available knowledge into a single mathematical model and to subject that model to challenges via simulations with available experimental data. As a first stage, then, the authors developed a simplified model, defining the structure and the different parameters that represent the phenomena that occur during the hyperacute phase of ischemic stroke. First, the different critical points of the evolution of ischemic stroke, based on the available evidence on the pathophysiology of stroke, were identified. Those key steps were then related to the quantitative data obtained by magnetic resonance imaging and positron emission tomography scan. These two techniques allow the measurement of diverse key markers of cerebral metabolism: cerebral blood flow (CBF), oxygen extraction factor, cerebral metabolism rate of oxygen, and the apparent diffusion coefficient of water, among others. Those markers were organized together through mathematical equations, and changed over time in order to describe the evolution of an acute ischemic stroke. At each time during the evolution of stroke those parameters are summarized in a parameter called survival delay. This parameter made possible the definition of three different states for tissues-functional, infarcted, salvageable-as end point. Once the model was designed, simulations were performed to explore its internal validity. Simulation results were consistent with the reality of acute ischemic stroke and did not reveal any major drawbacks in the use of the model. The more rapid the decrease in CBF, the larger is the final infarcted area. The model also allowed for the characterization of two types of tissue in the penumbra: tissues with an initial metabolic impairment and tissues altered owing to the closeness of the ischemic area. The results of this experiment were consistent with what is known of acute ischemic stroke. The model integrated different markers of acute ischemic stroke into a single entity in order to mimic acute ischemic stroke, and has been shown to have a reasonable degree of internal validity.
Abstract: There are many causes for carnitine depletion during maintenance hemodialysis. Supplementation with L-carnitine in animals has been associated with improvement in some abnormalities also present in chronic renal failure. However, it is still controversial whether restoring plasma or tissue carnitine will correct clinical or biologic symptoms observed in maintenance hemodialysis. A systematic review is here performed to determine the effects of L-carnitine in maintenance hemodialysis patients. Eighty-three prospective trials were identified from 1978 to 1999 in which L-carnitine was randomly allocated in 21 trials. Change in serum triglycerides, cholesterol fractions, hemoglobin levels, erythropoietin dose, and other symptoms (muscle function, exercise capacity, and quality of life) were examined. A total of 482 patients in 18 trials were considered for analysis. There was no effect of L-carnitine on triglycerides, total cholesterol, or any of its fractions. Before the erythropoietin (EPO) era, L-carnitine treatment was associated with improved hemoglobin (P < 0.01) and with a decreased EPO dose (P < 0.01) and improved resistance to EPO when patients routinely received EPO. Muscle function, exercise capacity, and quality of life could not be reliably assessed because of the noncombinable nature of end points and the limited number of trials. In conclusion, L-carnitine cannot be recommended for treating the dyslipidemia of maintenance hemodialysis patients. By contrast, this review suggests a promising effect of L-carnitine on anemia management. The route of L-carnitine administration should be evaluated because there is no evidence as to the most efficient method of administration in maintenance hemodialysis.
Abstract: The use of pneumococcal polysaccharide vaccine (PPV) is low in some countries, maybe because of doubts regarding its efficacy. This meta-analysis aims at combining evidence from randomized trials of PPV assessing its efficacy in preventing Streptococcus pneumoniae related diseases in immunocompetent adults. In the fourteen trials totalling 48,837 patients retrieved, PPV prevents definite pneumococcal pneumonia by 71%, presumptive pneumococcal pneumonia by 40%, and mortality due to pneumonia by 32%, but not all-cause pneumonia or death. No preventive effect was seen in the subgroup of patients aged 55 years or more, possibly due to a lack of statistical power.
Abstract: Cancer is still considered from a physiopathological point of view as a disease of the cell. This concept is underlying the idea of cure. Treatment with curative intent should aim at eradicating all the tumoral cells. Local control is mandatory and essential in cancers localized in organ with vital function. In breast cancer a complex and controversial relationship exists between local relapse and increased risk of fatal distant metastasis. In case of organ preserving treatment, a complete local control is necessary from the start. If a too high risk of local relapse is foreseable, conservative treatment should not be recommended.
Abstract: The absolute benefit from antihypertensive therapy increases with the baseline risk. However, age is a major determinant of cardiovascular risk, so it is important to express therapeutic efficacy with indices for which age is not a confounder. With this aim we explored the expected gain in life expectancy without cardiovascular events according to age at the initiation of the treatment. The treatment effect estimated from the INDANA meta-analysis, was applied to the cardiovascular risk of a French hypertensive population, simulated from national vital statistics. The gain in life expectancy was estimated from the area between survival curves without events. The treatment effect varied according three different hypotheses: increasing, decreasing or constant effect. When assuming a constant treatment effect, our results show a 29 month gain without stroke for a man who began his treatment at 40 years, and 15 months if hypertension is screened and treatment initiated at 75 years. The gains without coronary heart disease are respectively of 11 and 6 months. The variation of treatment effect over time could have a major impact on the treatment benefit. The gain in life expectancy without events is a relevant decision tool, completing usefully the absolute benefit, since it takes into account the influence of age.
Abstract: Heart failure treatment has markedly changed during the last few decades, with demonstration of benefit of afterload reduction by vasodilator therapy and introduction of the concept of the deleterious consequences of the neuro-hormonal compensatory stimulation. Blockade of beta-adrenergic receptors, initially contra-indicated in heart failure, provide a marked reduction of mortality and morbidity in combination with diuretics and angiotensin-converting enzyme inhibitors, as demonstrated in many clinical trials. We performed a review of all clinical trials that compare beta-blockers vs. placebo in chronic heart failure. Beta-blockers with different pharmacological profiles have been tested, mainly metoprolol, bisoprolol, bucindolol and carvedilol. With progressive dose increment, tolerance of such treatment was generally good, left ventricular function improved, hospitalisations for heart failure were less frequent and mortality was reduced. The meta-analysis of the 16 randomised trials, with at least one death in each treatment group, provides a 24% relative risk reduction for such hospitalisations (95% CI=19%-29%) and 22% reduction for mortality (95% CI=16%-28%). Heterogeneity of beta-blocker effect for mortality was found and related to the non-significant benefit obtained in the BEST trial with bucindolol. When such a trial is excluded, the effect model analysis shows that relative risk reduction (beta-blocker induced benefit) is constant whatever the severity of the disease. The mechanism of beta-blocker induced benefit remains unclear, but is at least partly related to left ventricular function improvement and prevention of severe ventricular arrhythmias. In conclusion, beta-blocker treatment has become an established therapy for heart failure, in combination with diuretics and ACE inhibitors. Complementary informations will be needed to clarify the mechanism of benefit and to define the best therapeutic strategy according to the individual characteristics of patients with heart failure.
Abstract: The main purpose of this meta-analysis was to compare the outcomes of patients who randomly received mechanical valves or bioprosthesis, over a long-term clinical follow-up.We found only three trials meeting our selection criteria with a total of 1229 patients (8069. 5 patient-yr). Bleeding was more frequent in patients with mechanical prostheses both after 5 yr (RR=2.6; IC=[1.9;3.5]; P<0.0001) and 11 yr (RR=1.6; IC=[1.2;2.2]; P<0.001) of follow-up. However, the increased risk of bleeding at 11 yr was only statistically significant with mechanical prostheses in the aortic position (RR=1.93; IC=[1.36;2. 74]; P=0.0002). Reoperation was significantly more frequent in patients with bioprosthesis after 11 yr follow-up (RR=0.4; IC=[0.3;0. 6]; P<0.001). Endocarditis was more frequent after 11 yr (RR=0.6; IC=[0.3;0.95]; P<0.05) in patients with mechanical prostheses but these results were heterogeneous between mitral and aortic valves. The choice of valve type does not significantly influence survival.
Abstract: The optimal duration of oral anticoagulant therapy after a first episode of venous thromboembolism (VTE) is still a matter of debate. It is essential to balance the desired effect of the anticoagulants in reducing recurrences against the risk of major bleeding. The aims of this paper are to describe the current concepts in this field. Recent data, based on randomized controlled trials, suggest that it is necessary to tailor the duration of anticoagulation individually according to the topography of VTE and the presence of risk factors. A 6-week treatment for patients with isolated calf vein thrombosis is sufficient. For proximal thrombosis and/or pulmonary embolism, a short anticoagulant course is sufficient in patients with temporary risk factors (3 months), and a longer anticoagulant course (6 months at least) is recommended for cases with permanent risk factors or idiopathic VTE. For these high-risk of recurrence patients, an assessment of low- or fixed-dose oral anticoagulation is necessary in order to reduce the bleeding risk. It is not possible to precisely determine the optimal duration with the available data. We have already performed a meta-analysis on summary data that suggests a long course of oral anticoagulant therapy is superior to a short course. An individual meta-analytic approach is needed to draw more precise conclusions on an interesting and important clinical topic.
Abstract: BACKGROUND: Intravenous thrombolytic therapy is the standard care for patients with acute myocardial infarction, based upon its widespread availability and ability to reduce patient mortality well demonstrated in randomised trials. Despite its proven efficacy, thrombolytic therapy has limitations. Many patients are ineligible for treatment with thrombolytics. Of those given thrombolytic therapy, 10 to 15 percent have persistent occlusion or reocclusion of the infarct-related artery. Consequently, primary angioplasty (primary PTCA) has been advocated as a better treatment of myocardial infarction. OBJECTIVES: To determine whether primary coronary angioplasty is superior to thrombolytic therapy for the treatment of patients with acute myocardial infarction. SEARCH STRATEGY: Electronic search of The Cochrane Library (1998; Issue 2). MEDLINE (to January 1998); references from reviews, trials and previously published meta-analyses; and experts. Date of most recent searches January 1998. SELECTION CRITERIA: All unconfounded, randomised controlled trials comparing primary angioplasty against intravenous thrombolysis in patients with acute myocardial infarction DATA COLLECTION AND ANALYSIS: At least two independent reviewers abstracted data on morbidity and mortality and trial characteristics. The following outcomes were assessed: total mortality at the end of the study, reinfarction, stroke of any type, composite endpoint of death and reinfarction, recurrent ischemia, severe bleeding and coronary artery bypass grafting. MAIN RESULTS: Ten trials including 2573 subjects were identified. Compared to thrombolytic therapy, primary angioplasty was associated with a significant reduction in short-term mortality at the end of the studies (relative reduction in risk RRR = 32% 95%CI = 5%;50%). Similar reductions were observed for the rate of reinfarction (RRR = 52%, 95%CI = 30%;67%), recurrent ischemia (RRR = 54%; 95%CI = 39%, 66%) and for the combined criteria death or reinfarction (RRR = 46%; 95%CI=30%;58%). The frequency of strokes of any cause was significantly decreased by 66% (95%CI=28%;84%). No significant difference was observed for the incidence of major bleeding (relative risk RR =1.18, 95%CI = 0.73;1.90) but the confidence interval was large. The superiority of the primary angioplasty over thrombolysis in terms of the composite endpoint (mortality and reinfarction) was less with accelerated t-PA (RR=0.70, 95%CI=0.51;0. 97) than with streptokinase (RR=0.30, 95%CI=0.17;0.53). The biggest and most recent trial, Gusto 2B ( approximately approximately GUSTO-2B 97 approximately approximately ), which involved general as well as higly specialised centres, obtained less favorable results. REVIEWER'S CONCLUSIONS: This meta-analysis suggests that angioplasty provides a short-term clinical advantage over thrombolysis which may not be sustained. Primary angioplasty when available promptly at experienced centres, may be considered the preferred strategy for myocardial reperfusion. In most situations, however, optimal thrombolytic therapy should still be regarded as an excellent reperfusion strategy.
Abstract: BACKGROUND: The prevention of venous thromboembolic disease is less studied in medical patients than in surgery. METHODS: We performed a meta-analysis of randomised trials studying prophylactic unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) in internal medicine, excluding acute myocardial infarction or ischaemic stroke. Deep-vein thrombosis (DVT) systematically detected at the end of the treatment period, clinical pulmonary embolism (PE), death and major bleeding were recorded. RESULTS: Seven trials comparing a prophylactic heparin treatment to a control (15,095 patients) were selected. A significant decrease in DVT and in clinical PE were observed with heparins as compared to control (risk reductions = 56% and 58% respectively, p <0.001 in both cases), without significant difference in the incidence of major bleedings or deaths. Nine trials comparing LMWH to UFH (4,669 patients) were also included. No significant effect was observed on either DVT, clinical PE or mortality. However LMWH reduced by 52% the risk of major haemorrhage (p = 0.049). CONCLUSIONS: This meta-analysis, based on the pooling of data available for several heparins, shows that heparins are beneficial in the prevention of venous thromboembolism in internal medicine.
Abstract: OBJECTIVE: To assess the length of oral anticoagulant therapy (short versus long duration) after a first episode of venous thromboembolism (VTE). DESIGN: Meta-analysis of randomized controlled trials, comparing two durations of anticoagulation, identified in 1999 by a computerized search of the Cochrane Controlled Trial Register, Medline and Embase, completed by an extensive review of the references of pertinent articles. SETTING AND SUBJECTS: The meta-analysis was performed on literature data. Seven published controlled trials were included. Relative risks with 95% confidence intervals were computed using the relative risk logarithm method. Statistical significance was set up at 0.01 for the test of association. MAIN OUTCOME MEASURES: Outcomes are major haemorrhage and recurrence after a 12-month follow-up. RESULTS: For the recurrence end-point (sample size of 2304 patients), a duration treatment of 12-24 weeks seems preferable to a 3-6 week regimen, with a relative risk (RR) of 0.60 (95% CI: 0.45-0.79, P < 0.001). For the major haemorrhage end-point (1823 patients), the RR is not significantly different from 1 (RR = 1.43, 95% CI: 0.51-4.01, P = 0. 5). The results were similar for the subgroup 'permanent risk factors' or 'idiopathic VTE' (RR for recurrence = 0.48, 95% CI: 0. 34-0.68, P < 0.001). The tendency was similar, although not reaching statistical significance, for the 'temporary risk factors' subgroup (RR for recurrence = 0.34, 95% CI: 0.13-0.93, P = 0.035). CONCLUSIONS: After a first episode of VTE, a long-term treatment regimen allows a significant reduction in the incidence of recurrences without increasing the incidence of bleeding events.
Abstract: Meta-analysis is a systematic and quantified synthesis of all clinical trials studying the same question. It is systematic because it implies an exhaustive search for all trials of the studied treatment, favourable or not, published and unpublished. It is quantified because it is based on statistical calculations leading to an estimation of the degree of the effect of the treatment. The use of statistical techniques allows to take into account the fact that different results can be obtained in different studies only by chance. Meta-analysis can be used to assess the efficacy of a treatment or to study the factors that modify this efficacy.
Abstract: Medical practice is most strongly founded when based on the results of well conducted clinical trials. Clinical trial results normally enter the domain of medical knowledge and practice through their publication in scientific journals. This in itself poses problems of accessibility and selection. The results of this is a slow and selective diffusion of new medical facts which has a consequent cost in human lives and human suffering. In an attempt to shorten this information path initiatives such as the Cochrane collaboration produce and maintain systematic reviews by speciality of the current state of knowledge. The ability to store a representation of a clinical trial in a standard form seems to us to be a necessary condition for the efficient and reproducible preparation of systematic reviews. Furthermore the consequent increased accessibility of research results due to the existence of the summaries would itself be of great use. In this aim a relational database client server system was developed and we publish here the results of our preliminary findings, including the data model, which we feel is an important contribution to the future discussion and development of computer based representations of clinical trial protocols and results and their use in clinical decision making.
Abstract: OBJECTIVE: To establish, using a systematic review and meta-analysis, whether there is any evidence from randomised controlled clinical trials of the efficacy of homeopathic treatment in patients with any disease. DATA SOURCES: Published and unpublished reports of controlled clinical trials available up to June 1998, identified by searching bibliographic databases (Medline, Embase, Biosis, PsychInfo, Cinahl, British Library Stock Alert Service, SIGLE, Amed), references lists of selected papers, hand searching homeopathic journals and conference abstracts, and contacting pharmaceutical companies. TRIALS SELECTION: Trials were selected using an unblinded process by two reviewers. The selection criteria were randomised, controlled trials in which the efficacy of homeopathic treatment was assessed relative to placebo in patients using clinical or surrogate endpoints. Prevention trials or those evaluating only biological effects were excluded. One hundred and eighteen randomised trials were identified and evaluated for inclusion. Sixteen trials, representing 17 comparisons and including a total of 2,617 evaluated patients, fulfilled the inclusion criteria. DATA EXTRACTION: Data were extracted by two reviewers independently, using a summary form. Disagreements were resolved by a third person. DATA SYNTHESIS: The evidence was synthesised by combining the significance levels (P values) for the primary outcomes from the individual trials. The combined P value for the 17 comparisons was highly significant P = 0.000036. However, sensitivity analysis showed that the P value tended towards a non-significant value (P = 0.08) as trials were excluded in a stepwise manner based on their level of quality. CONCLUSIONS: There is some evidence that homeopathic treatments are more effective than placebo; however, the strength of this evidence is low because of the low methodological quality of the trials. Studies of high methodological quality were more likely to be negative than the lower quality studies. Further high quality studies are needed to confirm these results.
Abstract: PRIMARY PREVENTION: A meta-analysis of the 7 available randomized cholesterol lowering trials (2 on statins, 2 on fibrates, 2 on resins and 1 on diet) demonstrates a significant 24% relative reduction in the frequency of fatal and non-fatal coronary events, leading to a significant 14% relative reduction in coronary disease related mortality. For total mortality, the statin trials were not comparable with other treatments where there was a trend to overmortality. With the 2 statin trials, there was a nonsignificant 13% reduction in total mortality. SECONDARY PREVENTION: A meta-analysis of the 13 available randomized trials (3 with clofribrate, 1 with gemfibrozil, 2 with nicotinic acid, and 4 with diet) showed a significant 21% reduction in the frequency of fatal and non-fatal coronary events, coronary mortality and total mortality. For total mortality, only the result of the 2 statin trials was significant (-20%). BENEFICIAL EFFECT OF STATINS, ABSOLUTE VALUES: Measured as the number of patients to treat for 5 years in order to avoid 1 event (NNT), there is a clinically pertinent benefit of secondary prevention (NNT = 15 for events, NNT = 30 for coronary mortality). The absolute value is weaker when patients with minimally elevated cholesterol levels are included. For primary prevention, the absolute value is low with NNT = 44 for events and NNT = 300 for coronary mortality. In addition, as these results were obtained in trials including populations with a much higher risk than the general French population, the absolute beneficial effect may not be pertinent in France except in high-risk patients who present, in addition to a high cholesterol level, other cardiovascular risk factors.
Abstract: OBJECTIVES: To study how satisfactory the contents of introductory courses in cardiovascular therapeutics, given to medical students in France, are with respect to the concepts of evidence-based medicine. METHODS: Medical school lecturers were asked to provide written course material used as part of medical school courses. Best-available evidence was classified as existent (including two therapeutic subclasses: indicated and contraindicated), and nonexistent. Four scores (from 0 to 10) were given, according to conformity with best-available evidence, and citation of randomized clinical trials (RCT), meta-analyses and therapeutic objectives. RESULTS: Thirty-four written documents were obtained from 43 faculties. Although the score (mean +/- SEM) of conformity with best-available evidence was 5.43 +/- 0.28 for the existent best-available evidence class, the corresponding scores for the citation of RCT, meta-analyses, and therapeutic objectives were, respectively, 1 +/- 0.2, 0.16 +/- 0.07, and 2.7 +/- 0.3. The four scores were highest when the best-available evidence belonged to the indicated class, intermediate when best-available evidence was nonexistent, and lowest for the contraindicated class (P < .05). These scores were significantly higher when the printed material was intended for specialists. CONCLUSION: Despite some limitations, the extent of agreement with the best-available evidence is only moderate. Pathophysiologic reasoning is largely preferred to justify the choice of therapeutics recommended to medical students.
Abstract: The general objective of randomized clinical trials is to assess if the treatment effect on a given population is clinically meaningful. In this way, one obtains an average estimate of the treatment effect over the trial population. However, a growing need for medical practitioners is to be able to predict with sufficient precision the efficiency of a given treatment for a given patient. There is little information in the literature about this issue. We have previously proposed a treatment-startified Cox model including interaction between treatment and patient's covariates, to identify and predict the responders to a therapy. In this paper, we focus on the assessment of the predictive power of the model. The performance of the predictive model for a population and for an individual was statistically validated internally and externally from several aspects. The prediction correlates well with the observation. Thus, we suggest that this approach would be useful in identifying and predicting the responders to a therapy, subject to an appropriate and more extensive validation process in real setting.
Abstract: The four indices for a binary outcome or therapeutic objective are: the odds ratio, the relative risk, the absolute benefit and the number of patients to treat. For a continuous outcome, the effect size is the best choice. The odds ratio approximates the relative risk. The difference may be large in some instances. The number of patients to treat is the reciprocal of the absolute benefit. Although they are built on the same two quantities, they are not interchangeable and should not be considered in the same way. Moreover, their meaning is not straightforward and they can be misused.
Abstract: Efficacy indices measure the efficacy of therapies. They derive, by definition, from two quantities, the basal or control risk of event, Rc, observed in the control group, and the on-treatment risk, Rt, observed in the treated group. In clinical trials and meta-analyses, each is an unbiased measure of efficacy. Although they are a combination of frequencies, these indices are used in clinical practice to predict the benefit in treated patients. Their relevance to express efficacy depends on the type of clinical condition, and is better for acute diseases than for chronic diseases. In order to be useful for prescribers, they should meet certain specifications. In addition, they should be considered in the more general framework of effect models.
Abstract: In chronic illness, when death or a non-fatal event can occur at any time, the current efficacy indices are no longer appropriate to express the effect of the treatment on the potential therapeutic objectives. The inappropriateness is not dependent on the effect model. Clues for solutions are proposed.
Abstract: AIMS: To develop a predictive clinical risk score of post-operative morbidity after coronary artery bypass grafting. METHODS AND RESULTS: Data were collected retrospectively from 679 patients undergoing emergency or planned bypass surgery between 1 January and 31 December 1996. The incidence of morbidity was 23%. Multivariate stepwise logistic regression analysis on two-thirds of the patients identified eight independent risk factors for severe morbidity. Six of these were pre-operative: symptomatic right heart failure, previous ventricular arrhythmias, previous coronary bypass surgery, chronic pulmonary disease, ST changes on pre-operative electrocardiogram, body mass index <24 kg. m-2, and two were intra-operative factors: the surgeon who operated, and the cardiopulmonary bypass time. A predictive clinical risk score was developed with the six pre-operative risk factors. The negative predictive value of the model is 87% and the area under the receiver operating characteristic curve is 0.77. When tested on the remaining patients not used for developing the model, the area under the curve is 0.65. CONCLUSION: This pre-operative risk score provides a simple method of risk stratification for patients undergoing coronary artery surgery. However, as for all predictive models, the performance of the score decreases when applied to a population other than that used to develop it.
Abstract: Efficacy indices do not contain the same information although they are all combinations of the same two quantities. Therefore, one should choose the proper index. Actually, none is entirely appropriate. Each more or less meets the specifications, depending on the underlying effect model for the therapy considered. However, one can say that the absolute benefit is more appropriate from the patient's point of view, the relative from the scientific point of view and the number of patients to treat from the policy maker's point of view. Nevertheless, this classification needs to be considered with caution. Finally, it emerges from the review that none is fully relevant to express the efficacy of a therapy, even in the most suitable condition, the acute illness.
Abstract: BACKGROUND: The aim of this meta-analysis was to assess the efficacy of antiviral agents to prevent, in solid organ transplant recipients, cytomegalovirus infection and symptomatic disease and to decrease the incidence of acute rejection, graft loss, and death. METHODS: Of the studies identified, 13 met the following inclusion criteria: prospective randomized study, in adults or pediatric recipients of a solid organ transplant, where one group in the study received a prophylactic treatment with acyclovir and/or ganciclovir begun before the cytomegalovirus infection and a control group was not treated or receive placebo. RESULTS: Prophylactic treatment was found to be associated with a significant decrease of cytomegalovirus disease compared with placebo or no treatment, using the logarithm of relative risk method (relative risk=0.50; 95% confidence interval, 0.40-0.62; P-value for chi-square association <0.001). Prophylactic treatment decreased also the rate of cytomegalovirus infection (relative risk=0.74; 95% confidence interval, 0.62-0.88; P<0.001). Our analysis failed to show a significant decrease of graft loss, acute rejection, and death in the prophylactic treatment group. Subgroup analysis based on the type of antiviral agent (acyclovir or ganciclovir) and on the type of organ (kidney or liver) gave comparable results. CONCLUSION: The use of antiviral agents for the prevention of cytomegalovirus disease and cytomegalovirus infection in solid organ transplantation is supported by this meta-analysis.
Abstract: The variations in the pharmacological effects induced by timing errors in drug intake are compared for two drugs, one acting by way of an effect compartment and the other directly from the central compartment. A simulation was performed for two drugs having the same concentration-effect relationship at the receptor site, the same mean effect at equilibrium and identical concentrations in the central compartment. In this article. Patrice Nony, Michel Cucherat and Jean-Pierre Boissel discuss how, for the same variability of concentrations in the central compartment, the variations in mean effects are different. When there is a large variability in the interval separating two consecutive doses, the model that includes an effect compartment dampens the pharmacokinetic variability present in the central compartment. Such an approach may be useful for the prescription recommendations of drugs, especially those with narrow therapeutic indices.
Abstract: Hypercholesterolemia or hypertension are continuous risk factors for coronary heart disease. When a preventive action is carried out against such a risk factor, it is necessary to specify a risk factor level value, named the treatment threshold, above which a subject should be treated. But a non-arbitrary determination of this threshold value is impossible from the epidemiological data. A method for the non-arbitrary determination of the treatment threshold value is presented, based upon mathematical modelling of the clinical and economics consequences of the prevention policy in the whole population. In a cost-effectiveness approach, the model was used to estimate the cost per coronary event prevented according to the threshold value for blood cholesterol. It was found that a minimum in this outcome proposed as the optimum treatment threshold. It is possible, from a public health point of view, to determine an optimum, non-arbitrary treatment threshold value in the prevention of coronary heart disease with cholesterol-lowering interventions. The model proposed here could be useful in decision making processes.
Abstract: The effect of a given treatment for a given disease may be estimated from randomized controlled clinical trials, expressed as a single treatment effect averaged over the trial population. However, in recent years there has been an increasing willingness to individualize therapeutic decisions. The method we report here identifies responders by assessing the individual probability of an event, according to the treatment group. We used a treatment-stratified Cox regression model including interaction between treatment and patient's covariates, with common regression coefficients for treated and untreated, except for the special case of a prognostic variable which has an interaction with treatment. Further, we used a discriminate function based on the final model, representing the absolute individual therapeutic effect, to identify the patients to be treated according to a given threshold of clinical efficacy. The model was explored on the INDANA database (which pools individual patient data from clinical trials of anti-hypertensive drug intervention). Data on 36,444 patients, from five randomized controlled trials were included. The results show the relationship between the proportion of avoided events among the avoidable ones, and the proportion of patients treated who were responders, as a function of the threshold of absolute benefit defining responders. The confidence intervals of the absolute therapeutic benefit for each individual were calculated, by using the Monte Carlo simulation method. A comparison of the survival of treated and controlled individuals, in both subgroups of responders and non responders, illustrated the relevance of the model. We conclude that the tools for predicting individual therapeutic benefit do exist. It will be important to assess the reproducibility of these results in other models or in other populations before widespread application. It will be necessary to have a properly computerized environment and to train doctors to use these tools.
Abstract: BACKGROUND: Infection remains a serious complication after permanent pacemaker implantation. Antibiotic prophylaxis is frequently prescribed at the time of insertion to reduce its incidence, although results of well-designed, controlled studies are lacking. METHODS AND RESULTS: We performed a meta-analysis of all available randomized trials to evaluate the effectiveness of antibiotic prophylaxis to reduce infection rates after permanent pacemaker implantation. Reports of trials were identified through a Medline, Embase, Current Contents, and an extensive bibliography search. Trials that met the following criteria were included: (1) prospective, randomized, controlled, open or blind trials; (2) patients assigned to a systemic antibiotic group or a control group; (3) end point events related to any infection after pacemaker implantation: wound infection, septicemia, pocket abscess, purulent secretion, right infective endocarditis, inflammatory signs, a positive culture, septic pulmonary embolism, or repeat operation for an infective complication. Seven trials met the inclusion criteria. They included 2023 patients with established permanent pacemaker implantation (new implants or replacements). The incidence of end point events in control groups ranged from 0% to 12%. The meta-analysis suggested a consistent protective effect of antibiotic pretreatment (P=.0046; common odds ratio: 0.256, 95% confidence interval: 0.10 to 0.656). CONCLUSIONS: Results of the present meta-analysis suggest that systemic antibiotic prophylaxis significantly reduces the incidence of potentially serious infective complications after permanent pacemaker implantation. They support the use of prophylactic antibiotics at the time of pacemaker insertion to prevent short-term pocket infection, skin erosion or septicemia.
Abstract: BACKGROUND: beta-Blockers have improved symptoms and reduced the risk of cardiovascular events in studies of patients with heart failure, but it is unclear which end points are most sensitive to the therapeutic effects of these drugs. METHODS AND RESULTS: We combined the results of all 18 published double-blind, placebo-controlled, parallel-group trials of beta-blockers in heart failure. From this combined database of 3023 patients, we evaluated the strength of evidence supporting an effect of treatment on left ventricular ejection fraction, NYHA functional class, hospitalizations for heart failure, and death. beta-Blockers exerted their most persuasive effects on ejection fraction and on the combined risk of death and hospitalization for heart failure. beta-Blockade increased the ejection fraction by 29% (P<10(-9)) and reduced the combined risk of death or hospitalization for heart failure by 37% (P<0.001). Both effects remained significant even if >90% of the trials were eliminated from the analysis or if a large number of trials with a neutral result were added to the analysis. In contrast, the effect of beta-blockade on NYHA functional class was of borderline significance (P=0.04) and disappeared with the addition or removal of only 1 moderate-size study. Although beta -blockade reduced all-cause mortality by 32% (P=0.003), this effect was only moderately robust and varied according to the type of ss-blocker tested, ie, the reduction of mortality risk was greater for nonselective beta-blockers than for beta1-selective agents (49% versus 18%, P=0.049). However, selective and nonselective beta-blockers did not differ in their effects on other measures of clinical efficacy. CONCLUSIONS: These analyses indicate that there is persuasive evidence supporting a favorable effect of beta-blockade on ejection fraction and the combined risk of death and hospitalization for heart failure. In contrast, the effect of these drugs on other end points requires additional study.
Abstract: BACKGROUND: Cognitive therapy (CT) has been studied in 78 controlled clinical trials from 1977 to 1996. METHOD: The meta-analysis used Hedges and Olkin d+ and included 48 high-quality controlled trials. The 2765 patients presented non-psychotic and non-bipolar major depression, or dysthymia of mild to moderate severity. RESULTS: At post-test CT appeared significantly better than waiting-list, antidepressants (P < 0.0001) and a group of miscellaneous therapies (P < 0.01). But, CT was equal to behaviour therapy. As between-trial homogeneity was not met, the comparisons of CT with waiting-list or placebo, and other therapies should be taken cautiously. In contrast, between-trial homogeneity was high for the comparisons of CT with behaviour therapy and antidepressants. A review of eight follow-up studies comparing CT with antidepressants suggested that CT may prevent relapses in the long-term, while relapse rate is high with antidepressants in naturalistic studies. CONCLUSION: CT is effective in patients with mild or moderate depression.
Abstract: There is clear evidence for a cancer cure. The hypothesis behind a treatment with curative intent is the ability to eradicate all the cancer cells of a tumour. Out of three cancer deaths, one is related to local failure. In some cancers like breast carcinoma, death is mainly in relation with the development of distant metastases. Even in such a tumour, an improvement in local control can translate as better survival. Radiation therapy, often in association with surgery, is playing a major role in tumour local control. Such a local control is mandatory if cure is at aim. One of the main goals of clinical research is to find a good compromise between local control of the disease and a non mutilating surgical approach.
Abstract: The efficacy of a drug is a quantitative concept rather than a qualitative one. This quantity is expressed by several efficacy indices. None of them meet all the requirements. However, that of absolute benefit is especially suitable for the patients because it tells them the exact gain they can expect from taking the treatment. The absolute benefit varies according to patients' profiles because it interacts with some components of these profiles. In theory, such interactions can be used to predict the size of the absolute benefit for each patient, as well to describe better than with the current tools the therapy target population. We explain why meta-analysis and effect models are means of improving the prediction of the size of the effect and the definition of the therapy target population.
Abstract: Meta-analysis of clinical trial data is an increasingly important method in clinical research, particularly in the field of therapeutic evaluation. This method uses some specific statistical techniques which are not all available on standard packages and therefore require specific developments. This paper describes a program designed to help medical researchers perform meta-analyses of clinical trial data with dichotomous outcomes. This program includes the various statistical methods of meta-analysis and enables cumulative meta-analysis and sub-groups to be performed. A robustness index can be determined and the results obtained in table and graphic formats. Data-editing and data-manipulating facilities are also possible. Much care has been taken to make the user interface as user-friendly as possible, so that the program is within the reach of all medical researchers.
Abstract: The APSI trial was a randomized placebo-controlled trial designed to assess the efficacy of 1 year of treatment by acebutolol in high-risk patients who had survived an acute myocardial infarction. At 1 year there was a statistically significant 48% relative reduction in total mortality (p = 0.019) in favor of acebutolol. In 1995 a long-term mortality survey was undertaken through an administrative inquiry and contacts with investigators. The vital status of 586 of the 607 (96.5%) patients enrolled was known at the cutoff date and all these patients were followed up for at least 5 years. During follow-up (in-trial and post-trial period), 74 deaths (24.8%) occurred in the acebutolol group and 96 (31.1%) in the placebo group (p = 0.10). No difference between the 2 groups was observed for the number of deaths that occurred after the end of the trial: 55 deaths (19.6%) among the 281 survivors in the acebutolol group and 59 deaths (21.7%) (p = 0.70) among the 272 survivors in the placebo group. The annual hazard rate (annual death rate), calculated year by year using the actuarial method, was significantly different (p < 0.01) only for the first year and was not significantly different thereafter. Thus, the initial benefit obtained in 1 year of treatment by acebutolol lasts for 5 years.
Abstract: In this paper we present a brief overview of the growing concern to standardize definitions and terminology in meta-analysis. This tool has become inescapable in both drug research and therapeutic evaluation. The performed and published meta-analyses are increasing, as well as the variation in the meaning of the terms used in meta-analysis. In the second part of the paper we propose glossary of the most common terms used in reports of meta-analyses. The glossary has been written by only one group of scientists, the definitions are therefore proposed to the scientific community as working definitions, to be subject to reactions from leaders in meta-analysis.
Abstract: Meta-analyses of Furberg's original data (after correction of two minor errors) were performed using six different methods. Only three of them gave significant results at p < 0.05. The sensitivity analysis showed that taking into account some of the criticisms applied to the original meta-analysis did not change the results. When all the criticisms were considered together, the 95 per cent confidence interval of the odds ratio for mortality was [0.96; 1.31] instead of [1.06; 1.37] originally (p = 0.14 and p = 0.03 respectively), and the dose excess mortality relationship stressed by Furberg disappeared. When the selection of the studies to be entered in a meta-analysis is not straightforward, a sensitivity analysis should be performed.
Abstract: The effect models are defined as the simple or complex relation that the risk in the treatment group follows when the risk in the control group varies. The standard statistical methods of meta-analysis are based on simple effect models. The use of these methods could induce inaccurate or erroneous results in more complex situations. In this case, it is necessary to adopt a more appropriate effect model, such as the linear effect model. The properties of this kind of model allow the possibility that a treatment can be beneficial and harmful at the same time, in function of the risk without treatment. From this observation, it is advisable to be careful with the use of simple effect models in meta-analysis which can submerge interesting information in the synthesis.
Abstract: The aim of therapeutic information is that people who need it have access to data of the highest level of evidence. In this context, a message is defined as the medium of information. The conditions for an ideal message to the prescriber are described: its content, the qualities it must meet, and the functional issues it will tackle. An example illustrates the importance of the form of a message. The difference between recommendation and message is highlighted.
Abstract: Meta-analysis is being increasingly used in therapeutic and clinical research to synthetize data from terminated clinical trials. Meta-analysis provides a powerful tool to objectively combine data in a quantitative manner, unlike the classical general review of literature, which is qualitative and subjective by definition, and thus not reproducible, and also the simple data pooling, methods which neglects the statistical heterogeneity between studies. The two most known objectives of meta-analysis are, to provide an objective decision when the trial results have produced contradictory or non-significant results, and to give a better estimation of the magnitude of the treatment effect. Precise methodological rules must be followed, but these rules are not known well enough in the scientific community. For example, particular care is necessary for the retrieval and selection of the trials: all available trials which satisfy predefined criteria of methodological validity should be taken into consideration. One of the main pitfalls in meta-analysis is the problem of unpublished trials, which represents a potential bias seen as an overestimation of treatment effect. In psychiatry, the applications of meta-analysis are numerous, especially in the domain of the treatment of depressive disorders, which will be developed in this paper. Several meta-analyses have been performed to assess the efficacy of antidepressants in major depression, especially with the "new antidepressants", which include the specific serotonine reuptake inhibitors (SSRIs). To date, these meta-analyses have shown that the main advantage of SSRIs was that they were better accepted, but without being more efficacious compared with classic antidepressants. The results of several of these meta-analyses are to be interpreted with the potential biases in mind, especially the publication bias and selection bias. Clinicians must be aware of the difficulties encountered in the choice of outcome criteria, and in deciding how to deal with patients that withdraw from treatment early (intention to treat analysis is the least biased solution for this problem.). Meta-analysis can therefore be helpful in establishing medical references in psychiatry, and to organize consensus conferences, but the limits of this method must be clearly recognized.
Abstract: Osteoporosis is the main cause of spine and hip fractures. Morbidity, mortality, and costs arising from hip fractures have been well documented. Thyroid hormones (TH) are widely prescribed, mainly in the elderly. Some studies (but not all) found a deleterious effect of suppressive TH therapy on bone mass. These conflicting data raised a controversy as to the safety of current prescribing and follow-up habits, which, in turn, raised major health-care issues. To look for a detrimental effect on bone of TH therapy, we performed a meta-analysis (by pooling standardized differences, using a fixed effect model) of all published controlled cross-sectional studies (41, including about 1250 patients) concerning the impact of TH therapy on bone mineral density (BMD). Studies with women receiving estrogen therapy were excluded a priori, as were studies with a high percentage of patients with postoperative hypoparathyroidism, when no separate data were available. We decided to stratify the data according to anatomical site, menopausal status, and suppressive or replacement TH therapy, resulting in 25 meta-analysis on 138 homogeneous subsets of data. The main sources of heterogensity between studies that we could identify were replacement or suppressive TH therapy, menopausal status, site (lumbar spine, femoral neck, Ward's triangle, greater trochanter, midshaft and distal radius, with various percentages of cortical bone), and history of hyperthyroidism, which has recently been found to impair bone mass in a large epidemiological survey. To improve homogeneity, we excluded a posteriori 102 patients from 3 studies, who had a past history of hyperthyroidism and separate BMD data, thus allowing assessment of the TH effect in almost all 25 subset meta-analyses. However, controls were usually not matched with cases for many factors influencing bone mass, such as body weight, age at menarche and at menopause, calcium dietary intake, smoking habits, alcohol intake, exercise, etc. For lumbar spine and hip (as for all other sites), suppressive TH therapy was associated with significant bone loss in postmenopausal women (but not in premenopausal women), whereas, conversely, replacement therapy was associated with bone loss in premenopausal women (spine and hip), but not in postmenopausal women. The detrimental effect of TH appeared more marked on cortical bone than on trabecular bone. Only a large long term prospective placebo-controlled trial of TH therapy (e.g. in benign nodules) evaluating BMD (and ideally fracture rate) would provide further insight into these issues.
Abstract: Biological/physiological data sampled over a period of 24 h can be subjected to a mathematical analysis to determine the presence of circadian rhythmicity. Several procedures have been proposed, most being complex. To render such an analysis simpler and easy to use by non-mathematicians, we developed and tested the cosinor technique using a commonly available commercial spreadsheet (Excel). It can be used to analyze equally or unequally time-spaced data over 24 h with missing data, as well as to calculate the significance and the main limit of the resultant circadian rhythm (mesor, amplitude, acrophase and their confidence limits). Examples of its application to hourly samples of plasma cortisol and minute-by-minute rectal temperatures are shown.
Abstract: In this paper we shall present the general principles of meta-analysis and will then discuss the various factors needed to evaluate a meta-analysis: description of the problem; definition of the outcome(s) (primary and secondary); methods for identifying and selecting trials for inclusion; statistical methods used; and the presentation and discussion of the results. We shall then examine other problems such as the detection of bias, the validity of the information provided by the meta-analysis, the problem of heterogeneity, the sensitivity and robustness of the meta-analysis, quality criteria for a meta-analysis, and how to locate published meta-analyses. Finally we present a decision algorithm which should help answer the question: should and can the results from the meta-analysis be integrated into clinical practice?
Abstract: General considerations about meta-analysis and the different steps of this technique are successively discussed: definition of the main objective, identification of the outcome, description of the retrieval and selection of trials, description of the statistical analysis and interpretation of the results. Advantages and drawbacks of the meta-analytical technique are then described: 1) scientific approach, possible quantification of the therapeutic effect, increase of the power of a future clinical trial, synthesis of contradicting results, assessment of the homogeneity, subgroup analysis, analysis of sensibility, scientific collaboration, help for therapeutic information. 2) retrospective approach, inconsistency among trials, potential biases, persistence of some unsolved methodological problems, difficulties for a critical reading and for the interpretation of conclusions. In addition, some examples of published meta-analyses are given to illustrate the advantages and limits mentioned above.
Abstract: The objective of classical treatments of cardiac failure (diuretics, digitalis) was to relieve patients' symptoms. Vasodilators and ACE inhibitors also improve morbidity and mortality. The introduction of the latter class of drugs for cardiac failure will, however, lead to a significant increase in the cost of medication at national level. These costs may increase even further in theory due to a predictable increase in the number of patients with cardiac failure (ageing of the general population, improved survival of cardiac patients) and due to the extension of prescription of these drugs to populations of subjects with cardiac failure hitherto relatively undertreated. On the other hand, economies may be realised in the management of cardiac failure related to fewer and shorter hospital admissions and reduced indirect costs or to the suppression of previous, less useful drugs (calcium antagonists, digitalis). Cost-effective analyses with ACE inhibitors carried out in different countries (Canada, netherlands) tend to show that the costs induced by prescription of these drugs are more than compensated by the economies realised by the reduction in hospital admissions. This is even more marked in the treatment of patients with severe cardiac failure. In subjects at low risk, the prescription of ACE inhibitors would not seem to be justified from both the clinical and economic points of view. It is up to each physician to decide the threshold of basic risk below which this treatment becomes "economically" acceptable.
Abstract: The prevention of lipid-related coronary risk by lipid lowering drugs or diet has been the object of several therapeutic trials. This meta-analysis comprises the 6 available primary prevention trials (representing 30,695 subjects). There was an overall reduction of non-lethal infarcts (-26%) and coronary events (-18%) in the treatment groups. There was a tendency to less coronary deaths (-10%), though not statistically significant, and no difference in mortality due to all causes was observed. Some questions remain unanswered about the fact that the reduced incidence of ischaemic heart disease did not affect global mortality. This fact could be explained by an inadequate duration of treatment or follow-up, to an effect limited to chronic infarction or to eventual unidentified adverse effects (the meta-analysis does not show any significant differences in mortality due to cancer or accidental death).
