Time filter

Source Type

Hôpital-Camfrout, France

Giraudeau B.,Center Cochrane Francais | Higgins J.P.T.,University of Bristol | Tavernier E.,French Institute of Health and Medical Research | Trinquart L.,Center Cochrane Francais | And 3 more authors.
Statistics in Medicine | Year: 2016

Meta-epidemiological studies are used to compare treatment effect estimates between randomized clinical trials with and without a characteristic of interest. To our knowledge, there is presently nothing to help researchers to a priori specify the required number of meta-analyses to be included in a meta-epidemiological study. We derived a theoretical power function and sample size formula in the framework of a hierarchical model that allows for variation in the impact of the characteristic between trials within a meta-analysis and between meta-analyses. A simulation study revealed that the theoretical function overestimated power (because of the assumption of equal weights for each trial within and between meta-analyses). We also propose a simulation approach that allows for relaxing the constraints used in the theoretical approach and is more accurate. We illustrate that the two variables that mostly influence power are the number of trials per meta-analysis and the proportion of trials with the characteristic of interest. We derived a closed-form power function and sample size formula for estimating the impact of trial characteristics in meta-epidemiological studies. Our analytical results can be used as a 'rule of thumb' for sample size calculation for a meta-epidemiologic study. A more accurate sample size can be derived with a simulation study. © 2016 John Wiley & Sons, Ltd. Source

Giraudeau B.,French Institute of Health and Medical Research | Giraudeau B.,University of Tours | Caille A.,French Institute of Health and Medical Research | Caille A.,University of Tours | And 4 more authors.
PLoS ONE | Year: 2012

Background: The Nuremberg code defines the general ethical framework of medical research with participant consent as its cornerstone. In cluster randomized trials (CRT), obtaining participant informed consent raises logistic and methodologic concerns. First, with randomization of large clusters such as geographical areas, obtaining individual informed consent may be impossible. Second, participants in randomized clusters cannot avoid certain interventions, which implies that participant informed consent refers only to data collection, not administration of an intervention. Third, complete participant information may be a source of selection bias, which then raises methodological concerns. We assessed whether participant informed consent was required in such trials, which type of consent was required, and whether the trial was at risk of selection bias because of the very nature of participant information. Methods and Findings: We systematically reviewed all reports of CRT published in MEDLINE in 2008 and surveyed corresponding authors regarding the nature of the informed consent and the process of participant inclusion. We identified 173 reports and obtained an answer from 113 authors (65.3%). In total, 23.7% of the reports lacked information on ethics committee approval or participant consent, 53.1% of authors declared that participant consent was for data collection only and 58.5% that the group allocation was not specified for participants. The process of recruitment (chronology of participant recruitment with regard to cluster randomization) was rarely reported, and we estimated that only 56.6% of the trials were free of potential selection bias. Conclusions: For CRTs, the reporting of ethics committee approval and participant informed consent is less than optimal. Reports should describe whether participants consented for administration of an intervention and/or data collection. Finally, the process of participant recruitment should be fully described (namely, whether participants were informed of the allocation group before being recruited) for a better appraisal of the risk of selection bias. © 2012 Giraudeau et al. Source

Escalas C.,French Institute of Health and Medical Research | Dalichampt M.,Assistance Publique Hopitaux de Paris | Combe B.,Montpellier University Hospital Center | Fautrel B.,University Pierre and Marie Curie | And 5 more authors.
Annals of the Rheumatic Diseases | Year: 2012

Objective: To assess the association of adherence to the 2007 recommendations of the European League Against Rheumatism (EULAR) for managing early arthritis and radiographic progression and disability in patients Methods: The authors conducted a prospective population-based cohort study. The ESPOIR cohort was a French cohort of 813 patients with early arthritis not receiving disease-modifying antirheumatic drugs (DMARDs). Adherence to the 2007 EULAR recommendations was defined by measuring adherence to three of the recommendations concerning the initiation and early adjustment of DMARDs. The study endpoints were radiographic progression, defined as the presence of at least one new erosion between baseline and 1 year, and disability as a heath assessment questionnaire score ≥1 at 2 years. A propensity score of being treated according to the recommendations was developed. Results: After adjustment for propensity score, treatment centre and the main confounding factors, patients without recommendation adherence were at increased risk of radiographic progression at 1 year, and of functional impairment at 2 years (OR 1.98, (95% CI: 1.08 to 3.62 and OR: 2.36, (95% CI: 1.17 to 4.67), respectively). Conclusions: Early arthritis patients whose treatment adhered to the 2007 EULAR recommendations seemed to benefit from such treatment in terms of risk of clinical and radiographic progression. Using a propensity score of being treated according to recommendations in observational studies may be useful in assessing the potential impact of these recommendations on outcome. Copyright Article author (or their employer) 2012. Source

Touze E.,University of Paris Descartes | Touze E.,University of Caen Lower Normandy | Trinquart L.,University of Paris Pantheon Sorbonne | Felgueiras R.,Center dEpidemiologie Clinique | And 10 more authors.
Stroke | Year: 2013

BACKGROUND AND PURPOSE - Compared with carotid endarterectomy (CEA), carotid angioplasty and stenting (CAS) is associated with a higher risk of procedural stroke or death especially in patients with symptomatic stenosis. However, after the perioperative period, risk is similar with both treatments, suggesting that CAS could be an acceptable option in selected patients. METHODS - We performed systematic reviews of observational studies of procedural risks of CEA or CAS and extracted data on 9 predefined risk factors (age, contralateral carotid occlusion, coronary artery disease, diabetes mellitus, sex, hypertension, peripheral artery disease, and type and side of stenosis). We calculated pooled relative risks of procedural stroke or death. Factors with differential effects on risk of CAS versus CEA were identified by interaction tests and used to derive a rule. The rule was tested using individual patient data from randomized trials of CAS versus CEA from the Carotid Stenting Trialists' Collaboration (CSTC). RESULTS - We identified 170 studies. The effects of sex, contralateral occlusion, age, and restenosis (SCAR) on the procedural risk of stroke or death differed. Patients with contralateral occlusion or restenosis and women <75 years were at relatively low risk for CAS (SCAR negative), with all others being high risk (SCAR positive). Among the 3049 patients in the CSTC validation, 694 (23%) patients were SCAR negative. The pooled RR of procedural stroke and death with CAS versus CEA was 0.93 (0.49-1.77; P=0.83) in SCAR-negative and 2.41 (1.68-3.45; P<0.0001) in SCAR-positive patients (P [interaction]=0.05). CONCLUSIONS - The SCAR rule is potentially useful to identify patients in whom CAS has a similar risk of perioperative stroke or death to CEA. © 2013 American Heart Association, Inc. Source

Lonjon G.,French Institute of Health and Medical Research | Boutron I.,French Institute of Health and Medical Research | Boutron I.,Center dEpidemiologie Clinique | Boutron I.,University of Paris Descartes | And 14 more authors.
Annals of Surgery | Year: 2014

OBJECTIVE: We aimed to compare treatment effect estimates from NRSs with PS analysis and RCTs of surgery. BACKGROUND: Evaluating a surgical procedure in randomized controlled trials (RCTs) is challenging. Nonrandomized studies (NRSs) involving use of propensity score (PS) analysis to limit bias are of increasing interest. DESIGN: Meta-epidemiological study. METHODS: We systematically searched MEDLINE via PubMed for all prospective NRSs with PS analysis evaluating a surgical procedure. Related RCTs, addressing the same clinical questions, were systematically retrieved. Our primary outcome of interest was all-cause mortality. We also selected 1 subjective outcome. We calculated the summary odds ratios (OR) for each study design, the ratio of OR (ROR) between the designs and the summary ROR across clinical questions. An ROR < 1 indicated that the experimental intervention is more favorable in NRSs with PS analysis than RCTs. RESULTS: We retrieved 70 reports of NRSs with PS analysis and 94 related RCTs evaluating 31 clinical questions, of which 22 assessed all-cause mortality and 26 a subjective outcome. The combined ROR for all-cause mortality was 0.83 (95% confidence interval: 0.65-1.04). For subjective outcomes, the combined ROR was 1.07 (0.87-1.33). CONCLUSIONS: There was no statistically significant difference in treatment effect between NRSs with PS analysis and RCTs. Prospective NRSs with suitable and careful PS analysis can be relied upon as evidence when RCTs are not possible. Copyright © 2013 by Lippincott Williams & Wilkins. Source

Discover hidden collaborations