Fig. 2

Percentage of studies included in the review that were incorporated into a meta-analysis for any outcome (blue line) and for the review’s main outcome (red bars)

Notes: This Figure excludes the 50 systematic reviews in whom a meta-analysis was not possible: 35 systematic reviews that each included 0 studies (i.e., “empty reviews”) and 15 systematic reviews included that each included only 1 study. When the blue line is non-0 but the red bars are 0, it implies that the systematic review did not conduct a meta-analysis for the main outcome, but did so for ≥1 of the remaining outcomes