382,577 papers found

The investigation of heterogeneity remains an essential but difficult issue in the conduct of meta-analysis. We reviewed standard and graphical methods used to explore heterogeneity in meta-analysis and publications from January 2005 to April 2007 regarding meta-analyses that focused on perinatal health topics. We asse…

The multiple sclerosis (MS) community read recently, with some surprise, the conclusions from a systematic review of the major therapeutic recombinant interferon trials in relapsing-remitting (RR)MS.1 The review stated that: 'their (recombinant interferons) clinical effect beyond 1 year is uncertain and new trials are…

Meta-analyses involving the synthesis of evidence from cluster randomization trials are being increasingly reported. These analyses raise challenging methodologic issues beyond those raised by meta-analyses which include only individually randomized trials. In this paper we review and comment on a selected number of th…

Epidemiological studies, more specifically those related to analytical epidemiology are a major determinant of evidence-based medicine. When classifying the value of the different epidemiological studies, based on their level of causality, cohort studies are ranked higher than case-control studies, mainly due to the fa…

QUESTION: Many of my female patients, those who plan pregnancy or have conceived, are afraid of any intake of caffeine. This often makes their lives miserable during pregnancy. Is this justified scientifically? ANSWER: Motherisk's recent meta-analysis suggests that the risks for miscarriage and fetal growth retardatio…

Are meta-analyses the brave new world, or are the critics of such combined analyses right to say that the biases inherent in clinical trials make them uncombinable? Negative trials are often unreported, and hence can be missed by meta-analysts. And how much heterogeneity between trials is acceptable? A recent major cri…

Randomized trials are effective and usually unbiased for showing the average results in a selected outcome variable for treatment A versus treatment B, and meta-analyses produce an average of these averages. The results of both the trials and meta-analyses are often pragmatically unsatisfactory, however, because they d…

This paper reviews methods for deriving measures of effect for interrupted time-series (single case) designs. Limitations of prior models are described. Modifications of a regression approach developed by Center, Skiba, and Casey (1985-86, Journal of Special Education, 19, 387-400) which can simultaneously account for…

Epidemiological studies on low risks involve a number of major methodological difficulties. This review defines the concept of low risk and emphasises the need to control all large, possibly disease-related risk factors, before low risk factors can be evaluated. This procedure is also essential in identifying confoundi…

Summarizing epidemiologic data from multiple studies can be accomplished either by a meta-analysis of published findings or by pooling data and performing new analyses of enlarged data sets. Meta-analysis is relatively easy and inexpensive to perform but usually is restricted to examination of overall risks. Data pooli…

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Hamilton A, Gonzaga L, Amorim K, Wittneben JG, Martig L, Morton D, Martin W, Gallucci GO, Wismeijer D. Selection criteria for immediate implant placement and immediate loading for single tooth replacement in the maxillary esthetic zone: A systematic review and meta-analysis.…

Systematic reviews and meta-analyses are methods increasingly used in biomedical research since their introduction in the 1970s. They serve to replace other non-systematic and cherry-picked narrative reviews, which are highly variable in their approach, structure and content. Their increase in popularity parallels the…

The American Heart Association (AHA) recently published a meta-analysis that confirmed their 60-year-old recommendation to limit saturated fat (SFA, saturated fatty acid) and replace it with polyunsaturated fat to reduce the risk of heart disease based on the strength of 4 Core Trials. To assess the evidence for this r…

Meta-analysis allows for the aggregation of results from multiple studies to improve statistical inference for the parameter of interest. In recent years, random-effect meta-analysis has been employed to synthesize estimates of incidence rates of adverse events across heterogeneous clinical trials to evaluate treatment…

A wide variety of estimators of the between-study variance are available in random-effects meta-analysis. Many, but not all, of these estimators are based on the method of moments. The DerSimonian-Laird estimator is widely used in applications, but the Paule-Mandel estimator is an alternative that is now recommended. R…

Synapses are centrally involved in many brain disorders, particularly in psychiatric and neurodevelopmental ones. However, our current understanding of the proteomic alterations affecting synaptic performance in the majority of mental illnesses is limited. As a result, novel pharmacotherapies with improved neurological…

Systematic reviews should be distinguished from narrative reviews. In the latter, an editor asks an expert to sum up all of the information that is known about a particular topic. However, the expert is under no constraints regarding what he or she does, or does not, choose to include in the review. As a result, his or…