386,737 papers found

Although primary studies often report multiple outcomes, the covariances between these outcomes are rarely reported. This leads to difficulties when combining studies in a meta-analysis. This problem was recently addressed with the introduction of robust variance estimation. This new method enables the estimation of me…

Meta-analysis uses numerical tools to pool data and to estimate a summary effect size for the comparison of two interventions from a set of randomised controlled trials identified in a systematic review. An effect size is a single number that expresses the difference in outcome from the interventions. The most commonly…

Postoperative radiotherapy remains controversial in non-small cell lung cancer. The conclusions of several meta-analysis are still questioned, partly because of flaws in the randomized trials taken into account. The technological improvements of modern radiotherapy and several clinical observations have led to the laun…

Aspirin is used to prevent ischemic stroke and other types of cardiovascular disease. Seven trials of aspirin focusing on the effectiveness of primary prevention of stroke and other cardiovascular events have been performed, but three of these did not include women. Data from these trials, and one meta-analysis, sugges…

BACKGROUND: Meta-analysis has become accepted as a methodically rigorous research tool, and as a result, many meta-analyses have been undertaken in orthopedic trauma, the implication being that their conclusions have improved surgeons' knowledge and facilitated improved clinical care. There have been criticisms of the…

This article reviews the research support for Motivational interviewing (MI) so that practitioners can make informed decisions about the value and applicability of MI in their clinical work. We highlight the evidence from the three published meta-analyses of MI and a recent meta-analysis that we completed. MI is signif…

Systematic review and meta-analysis are assuming greater importance in influencing policy makers and clinical opinion worldwide. Many discussions and publications have considered the merits of meta-analysis of epidemiologic data.50 Some observers suggest that meta-analysis of observational studies should be abandoned a…

OBJECTIVE: To estimate the extent to which the practice of periodically updating meta-analyses causes inflation of the type I error and then to compare the estimate with the inflation caused by publication bias. We also present a simple method to adjust for the inflation associated with updating meta-analyses. STUDY D…

Statistical tests of heterogeneity and bias, in particular publication bias, are very popular in meta-analyses. These tests use statistical approaches whose limitations are often not recognized. Moreover, it is often implied with inappropriate confidence that these tests can provide reliable answers to questions that i…

The authors present a critical appraisal of the biological bases of altered fractionation and a brief overview of published randomized trials with conventional fractionation as the control arm, reviews and meta-analysis on altered fractionation radiotherapy in head and neck cancer. The major controversial issues emergi…

Systematic reviews help people to make well-informed decisions about health care by bringing together the relevant evidence, appraising it and, where appropriate, combining it in a meta-analysis. The ultimate aim for a systematic review should be to present all relevant data on all participants in all research judged t…

This chapter describes the basic steps in a systematic review to evaluate test accuracy, and the threats to validity of reviews inherent in each step. First, the problems to be addressed are specified in the form of well-structured questions (Step 1). This is a key step, as all other aspects of the review follow direct…

The methodology of evidence-based medicine (EBM) has become dominant in the clinical field to the detriment of historically validated paradigms. The philosophical background of EBM is considered and the strengths and flaws of its main tools (randomized trials and meta-analysis) are reviewed. The structural format of EB…

RATIONALE AND OBJECTIVES: In this review article, we present the definition and useful concepts of evidence-based medicine (EBM). The principles of EBM are provided and major steps of practicing EBM are described. MATERIALS AND METHODS: We emphasize the importance of the Cochrane Collaboration (see http://www.cochrane…

Homeopathy remains one of the most controversial subjects in therapeutics. This article is an attempt to clarify its effectiveness based on recent systematic reviews. Electronic databases were searched for systematic reviews/meta-analysis on the subject. Seventeen articles fulfilled the inclusion/exclusion criteria. Si…

Pneumococcal (PC) infections are common and dangerous. Polysaccharide PC vaccine is recommended in some countries for use in adults who have an increased risk of PC infection. Randomised studies of the clinical effect of polysaccharide PC vaccine in healthy adults reported a protective effect, which, in general, was no…

Contemporary aspects of research methods in sport and exercise psychology are discussed in this wide-ranging review. After an introduction centred on trends in sport and exercise psychology methods, the review is organized around the major themes of quantitative and qualitative research. Our aim is to highlight areas t…

When combining the results of independent studies it often happens that some studies are potentially aberrant either in quality or in actual values. Because aberrant studies are often at the extremes, we may wish to trim some of the largest and smallest effects. In such a case the use of p-values may well serve as a di…

The "evidence" in EBM must be of high quality in order to be useful, but this is not always the case. Even the "gold standard" of evidence-based medicine, the randomised clinical trial, is bedevilled by low inclusion rates and potentially important recruitment biases. "Real world" trials often do not give the same resu…

OBJECTIVE: To explain the concepts and application of Bayesian modelling and how it can be applied to the analysis of dental research data. BASIC DESIGN: Methodological in nature, this article introduces Bayesian modelling through hypothetical dental examples. SETTING: The synthesis of RCT results with previous evide…