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Meta-analysis: mistake or milestone in medicine?
  1. Farid Foroutan1,2,
  2. Gordon Guyatt2,
  3. Ana Carolina Alba1,
  4. Heather Ross1
  1. 1Ted Rogers Centre of Excellence in Heart Function, Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada
  2. 2Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Ontario, Canada
  1. Correspondence to Farid Foroutan, Ted Rogers Centre of Excellence in Heart Function, Peter Munk Cardiac Centre, University Health Network, Toronto, ON M5G 2C4, Canada; farid.foroutan{at}uhn.ca

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Since 1981, Evidence-Based Medicine (EBM) has evolved into a framework for partnering with patients to resolve or cope with health problems, taking full advantage of available research evidence.1 The modern practice of EBM relies on three fundamental principles1: (1) optimal clinical decision making requires a systematic review of the best available evidence; meta-analysis sometimes, though not always, strengthens associations, (2) using sophisticated framework for judging the quality or trustworthiness of evidence and (3) consideration of trade-offs between benefits, risks, burden and costs, on the basis of patients’ values and preferences.

Despite EBM’s wide acceptance over the past 30 years, scepticism remains. Specifically, sceptics of EBM’s first principle believe that our knowledge of cardiovascular medicine would be no different with or without the utilisation of systematic reviews and meta-analyses for ascertainment of evidence.2 Such beliefs are not unsupported on social media platforms such as Twitter, by means of tweets and retweets, over 270 000 knowledge users have expressed scepticism against systematic reviews and meta-analyses.3 In this editorial, we present a meta-analyst’s perspective, providing evidence to support EBM’s first principle regarding the use of systematic reviews and meta-analyses to better inform the cardiology audience.

Advantages of systematic reviews and meta-analyses

For any well-formulated research question, systematic reviews and meta-analyses can identify all the available relevant evidence (systematic search), critically appraise the risk of bias of the identified evidence, combine the results to increase statistical power (meta-analysis when appropriate), identify sources of variation across studies (subgroup analyses) and rate the overall quality of the evidence (certainty in the results).

Increased statistical power and precise estimates

History demonstrates the advantage of systematic reviews and meta-analyses over narrative reviews. In 1992, Antman et al4 compared expert recommendations for management of patients with myocardial infarction (MI) with the best evidence available at the time. The authors conducted a retrospective cumulative meta-analysis (performing a …

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