Obtaining medically meaningful answers from an overview of randomized clinical trials

Answers that have medical value can often be obtained from overviews of randomized clinical trials if care is taken in formulating a biologically sensible question and unbiased and careful methods are used in collecting, extracting and analysis the results. This article discusses some of the pitfalls that are encountered during this process, outlines some solutions and emphasizes the need for a conservative interpretation of the results.