The rough guide to systematic reviews and meta-analyses

The hierarchy of evidence based medicine postulates that systematic reviews of homogenous randomized trials represent one of the uppermost levels of clinical evidence. Indeed, the current overwhelming role of systematic reviews, meta-analyses and meta-regression analyses in evidence based heath care calls for a thorough knowledge of the pros and cons of these study designs, even for the busy clinician. Despite this sore need, few succinct but thorough resources are available to guide users or would-be authors of systematic reviews. This article provides a rough guide to reading and, summarily, designing and conducting systematic reviews and meta-analyses.