Pitfalls in meta-analysis.

Systematic reviews with meta-analyses are powerful instruments to synthesize research. If done correctly, they may constitute the highest level of evidence by combining several individual studies. As high-quality evidence is scarce in the field of complementary medicine, meta-analyses of randomized trials may shed new light on both efficacy and safety, but they must be properly conducted. In this commentary to a recently published paper we elaborate on methodological pitfalls in meta-analysis that every researcher should avoid to gain true high-quality evidence.