392,037 papers found

Motivated by the overwhelming success of genome-wide association studies, droves of researchers are working vigorously to exchange and to combine genetic data to expediently discover genetic risk factors for common human traits. The primary tools that fuel these new efforts are imputation, allowing researchers who have…

PURPOSE: This article introduces practicing urologists to the critical appraisal of systematic reviews and meta-analyses to guide their evidence-based clinical practice. MATERIALS AND METHODS: Using a urological clinical case scenario we introduce a 3-step process in evaluating systematic reviews and meta-analyses by…

Meta-analyses of multiple outcomes need to take into account the within-study correlation across the different outcomes. Here we focus on the meta-analysis of dichotomous outcomes that are mutually exclusive and exhaustive. Correlations between effect sizes for mutually exclusive outcomes are negative and can be obtain…

OBJECTIVE: To assess how different imputation methods used to account for missing variance data in primary studies influence tests of heterogeneity and pooled results from a meta-analysis with continuous outcomes. STUDY DESIGN AND SETTING: Point and variance estimates for changes in serum creatinine, glomerular filtra…

UNLABELLED: While meta-analysis provides a powerful tool for analyzing microarray experiments by combining data from multiple studies, it presents unique computational challenges. The Bioconductor package RankProd provides a new and intuitive tool for this purpose in detecting differentially expressed genes under two e…

BACKGROUND: Systematic reviews and meta-analyses of test accuracy studies are increasingly being recognised as central in guiding clinical practice. However, there is currently no dedicated and comprehensive software for meta-analysis of diagnostic data. In this article, we present Meta-DiSc, a Windows-based, user-frie…

Meta-analysis is an important tool for interpreting results of functional neuroimaging studies and is highly influential in predicting and testing new outcomes. Although traditional label-based review can be used to search for agreement across multiple studies, a new function-location meta-analysis technique called act…

Improving health and well-being from the consideration of isolated studies is problematic. Systematic reviews have been developed to address this problem and may include a quantitative data synthesis in the form of a meta-analysis, or a cumulative meta-analysis. The value of systematic reviews depends greatly on the av…

OBJECTIVE: We studied the influence of the methodologic quality of individual trials on the outcome of a landmark meta-analysis on thrombolytic therapy in acute myocardial infarction. From each study we extracted the number of patients in both groups who died in hospital or during follow-up. Methodologic quality was as…

Exploring the possible reasons for heterogeneity between studies is an important aspect of conducting a meta-analysis. This paper compares a number of methods which can be used to investigate whether a particular covariate, with a value defined for each study in the meta-analysis, explains any heterogeneity. The main e…

Meta-analysis methodology is developed for combining sibpair linkage results across multiple studies employing different study designs, some employing quantitative traits (e.g., blood pressure) and some employing qualitative traits (e.g., clinical hypertension), under the assumption that the underlying (disease) trait…

OBJECTIVE: Funnel plots (plots of effect estimates against sample size) may be useful to detect bias in meta-analyses that were later contradicted by large trials. We examined whether a simple test of asymmetry of funnel plots predicts discordance of results when meta-analyses are compared to large trials, and we asses…

Sickle cell disease (SCD) is a family of inherited blood disorders of variable severity which have in common haemolytic anaemia, recurrent painful crises, end-organ failure and the risk of reduced life expectancy. In Britain, the condition predominantly occurs among families of African or Afro-Caribbean origin. This st…

Multiple factors in the past encouraged physicians to order laboratory tests excessively and perhaps even abusively. The shift in the financing of health care to managed care and capitation will create an environment where physicians will be more receptive to laboratory efforts to influence their test ordering behavior…

In this commentary, we use evidence produced by the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) ten-year update of a meta-analysis of trials of adjuvant therapies for early breast cancer which started prior to 1985 to illustrate aspects of interpretations and uses of meta-analysis results. The following…

PURPOSE: To determine the diagnostic performance of technetium bone scanning in the setting of possible osteomyelitis in the foot of a patient who has diabetes or other vasculopathy. DESIGN: Meta-analysis. Data identification and study selection: To be eligible for inclusion, a report must have used intravenous techne…

Meta-analysis, a set of statistical tools for combining and integrating the results of independent studies of a given scientific issue, can be useful when the stringent conditions under which such integration is valid are met. In this report we point out the difficulties in obtaining sound meta-analyses of either contr…

This article presents a stepwise approach for conducting a meta-analysis of epidemiological studies based on proposed guidelines. This systematic method is recommended for practitioners evaluating epidemiological studies in the literature to arrive at an overall quantitative estimate of the impact of a treatment. Bende…

BACKGROUND: Current guidelines identify the choice of fluid resuscitation as important in minimizing the incidence of secondary brain injury from cerebral edema. It is widely accepted that isotonic crystalloid resuscitation fluids, specifically normal saline (NS), are optimal for resuscitation and that other relatively…

This study analyzes 1,000 meta-analyses drawn from 10 disciplines-including medicine, psychology, education, biology, and economics-to document and compare methodological practices across fields. We find large differences in the size of meta-analyses, the number of effect sizes per study, and the types of effect sizes…