Cosa ci insegnano le metanalisi: Pregi e limiti

The exponential increase in publications focusing on important clinical issues represents a major challenge for patients, physicians, and decision-makers, despite the braggadocio of many experts. Meta-analysis, when conducted within the context of a systematic review, offers an efficient and potent tool to summarize the clinical evidence accrued on a specific clinical question. Despite their many strengths, which include statistical precision, external validity, and the opportunity to analyze subgroups and moderators, meta-analyses also have many limitations. In addition, they are criticized because potentially an exercise in "mega-silliness", mixing "apples and oranges", unable to improve the quality of primary studies (in keeping with the say "garbage in-garbage out"), and focusing on an "average patient" who is only hypothetical. Yet, it is evident that metaanalyses will continue to play a key role in informing decision making whenever the best approach is not selfevident. Thus, it is mandatory to know their main features in order to use them critically and constructively, without being dominated nor scared.