title: Meta-analysis in medical research: potentials and limitations.
abstract: Meta-analysis, the statistical combination of results from several studies to produce a single estimate of a treatment effect or size of an association, continues to attract controversy. We illustrate and discuss the promises and limitations of meta-analysis. Meta-analysis of clinical trials can prevent delays in the introduction of effective treatments or lead to the timely identification of adverse effects. However, meta-analyses are liable to numerous biases, both at the level of the individual study and the selection of studies for inclusion in meta-analysis. The biases and confounding factors that threaten the validity of individual studies will also affect meta-analyses of observational studies. We argue that meta-analyses should only be performed within the framework of systematic reviews that have been prepared using methods that minimize bias and address the combinability of studies.
authors.affiliation: Department of Social and Preventive Medicine, University of Berne, Berne, Switzerland. zwahlen@ispm.unibe.ch
authors.forename: Marcel
authors.initials: M
authors.lastname: Zwahlen
authors.forename: Andrew
authors.initials: A
authors.lastname: Renehan
authors.forename: Matthias
authors.initials: M
authors.lastname: Egger
mesh_terms: D035843:Biomedical Research / Q000379:methods*; D018849:Controlled Clinical Trials as Topic; D006801:Humans; D008495:Medical Oncology; D015201:Meta-Analysis as Topic; D009203:Myocardial Infarction; D012196:Review Literature as Topic; D014572:Urology