Review of the evidence
Selection criteria for each question were determined a priori . Only comparative studies (systematic reviews, randomized controlled trials, cohort studies, case-control studies, and cross-sectional studies) were considered for inclusion. If randomized data were available, data from nonrandomized studies were excluded. Electronic and manual searches were conducted for each question. We searched PubMed and EMBASE through July 7, 2020. Additionally, we manually reviewed the reference lists of all relevant systematic reviews and included studies to find additional eligible studies. The titles and abstracts of all identified references were reviewed by a clinician and a methodologist from the GSG. Studies identified for full-text review were then reviewed by all members of the GSG, and any reasons for exclusion were noted.
Data from included studies were extracted by two members of the GSG. The quality of evidence from each included study was assessed using the appropriate risk-of-bias tool for each study design. The Cochrane RCT tool was used for randomized controlled trials.6 The Newcastle-Ottawa tool was used for cohort and case-control studies.7 QUADAS was used for diagnostic accuracy studies.8 Data on outcomes from similar studies were pooled when appropriate by using the random-effects model. All analyses were performed using RevMan,9 and all information was summarized as evidence profile tables.10