Thursday, June 30, 2016

Proposed new evidence-based medicine pyramid

Systematic reviews and meta-analyses have been placed at the top of the evidence pyramid for several good reasons. They provide more trustworthy answers and more precise estimates with narrower confidence intervals that are were not selected based on expert opinion, but rather based on a systematic procedure. However, credible systematic review can summarize biased evidence and poorly done systematic reviews can summarize well done trials. This challenges the placement on top. In addition, GRADE tells us that our certainty in evidence should be driven by many factors other than study design. Therefore, we propose 2 modifications to the pyramid to resolve these 2 challenges.

Figure 1.

Legend: The proposed new evidence-based medicine pyramid. (A) The traditional pyramid. (B) Revising the pyramid: (1) lines separating the study designs become wavy (Grading of Recommendations Assessment, Development and Evaluation), (2) systematic reviews are ‘chopped off’ the pyramid. (C) The revised pyramid: systematic reviews are a lens through which evidence is viewed (and applied).