382,842 papers found

OBJECTIVES: To illustrate the pitfalls of using meta-analysis to combine estimates of effect in trials that are highly varied and have a high potential for bias. METHODS: We used a random-effects meta-analysis to pool the results of 51 sham-controlled acupuncture trials of chronic pain published in English before 2008…

In September 2012 the Acupuncture Trialists' Collaboration published the results of an individual patient data meta-analysis of almost 18 000 patients in high quality randomised trials. The results favoured acupuncture. Although there was little argument about the findings in the scientific press, a controversy played…

This paper investigates the use of likelihood methods for meta-analysis, within the random-effects models framework. We show that likelihood inference relying on first-order approximations, while improving common meta-analysis techniques, can be prone to misleading results. This drawback is very evident in the case of…

Meta-analysis can be a powerful tool for demonstrating the applicability of a concept beyond the context of individual clinical trials and observational studies, including exploration of effects across different subgroups. Meta-analysis avoids Simpson's paradox, in which a consistent effect in constituent trials is rev…

Discovering genes involved in multiple types of cancers is of significant therapeutic importance. We show that collective evidence for such genes can be obtained via a form of meta-analysis that aggregates the results (rankings and p values) from various cancer-specific microarray experiments. This method is illustrate…

Efficacy, which we define as the effect of receiving intervention on health outcomes among a group of subjects, is the quantity of interest for many investigators. In contrast, intent-to-treat analyses in randomized trials and their analogue for observational before-and-after studies compare outcomes between randomizat…

Despite the rapidly growing number of meta-analyses in functional neuroimaging, the field lacks formal mathematical tools for the quantitative and qualitative evaluation of meta-analytic data. We propose to use replicator dynamics in the meta-analysis of functional imaging data to address an important aspect of neuroim…

Meta-analysis has a natural formulation as a Bayesian hierarchical model. The main theoretical difficulty is the construction of a sensible relationship between the parameters of the individual statistical experiments and the meta-parameter. Since that prior information on such a relationship is typically not available…

Meta-analysis is now a standard statistical tool for assessing the overall strength and interesting features of a relationship, on the basis of multiple independent studies. There is, however, recent acknowledgement of the fact that in many applications responses are rarely uniquely determined. Hence there has been som…

We examine different methods to pool binary outcomes used both in parallel and cross-over trials. Odds ratio (OR) estimators obtained from joint conditional probabilities in cross-over trials, such as the Mantel-Haenszel and Peto methods, are compared to an OR estimator using marginal results of cross-over trials. When…

Meta-analysis is increasingly used in hepatogastroenterology. Meta-analysis is of value to provide a systematic review of related trials and to display their results in an objective, easily understandable manner. When the trials are sufficiently homogeneous, meta-analysis can document the superiority, (a), or the lack…

Meta-analysis has become a popular technique in many areas of biomedical research. While there have been a number of studies and commentaries on the use of meta-analyses and systematic reviews of clinical trials of therapy, little is known about the use of meta-analysis techniques for the evaluation of screening data.…

Meta-analysis is increasingly applied in infectious diseases to summarize clinical data and to evaluate the strength, diversity, and deficiencies of evidence for medical questions of interest. We present an overview of the current status of meta-analysis in the area of infectious diseases and the lessons learnt from it…

Serum progesterone measurement has been advocated as a diagnostic tool in the non-invasive diagnosis of ectopic pregnancy. To assess the accuracy of a single serum progesterone measurement in the diagnosis of ectopic pregnancy, a meta-analysis was performed incorporating 26 studies evaluating the performance of single…

Meta-analysis applied to eight controlled clinical trials of coenzyme Q10 (CoQ10)-treatment of congestive heart failure revealed a significant improvement a several important cardiac parameters such as ejection fraction (EF), stroke volume (SV), cardiac output (CO), cardiac index (CI) and end diastolic volume index (ED…

Meta-analysis refers to quantitative methods to combine results from independent studies so as to draw overall conclusions. Frequently, results from dissimilar studies are inappropriately combined, resulting in suspect inferential synthesis. We present a straightforward method to identify and address this problem throu…

In this paper, we consider the role of meta-analysis and 'prospective meta-analysis' studies in childhood acute lymphocytic leukemia (ALL). In this issue, Valsecchi and Masera [1] give a thoughtful discourse, generally favorable to this approach. This article presents the opposite point of view. The aims of our article…

Meta-analyses of published data show a modest but significant survival or response rate benefit for chemotherapy plus supportive care over best supportive care alone in non-small cell lung cancer (NSCLC), but these findings may be biased in favor of positive results because they are literature based. A meta-analysis of…

Meta-analysis often requires pooling of correlated estimates to compute regression slopes (trends) across different exposure or treatment levels. The authors propose two methods that account for the correlations but require only the summary estimates and marginal data from the studies. These methods provide more effici…

An epidemiologically impeccable study does not bring answers to all the important questions. A structured and systematic integration of information from different studies of a given problem with a view to answering the original question or bringing additional information is the essence and objective of the meta-analyti…