Fig. 1

Trends over time for the most frequently cited RoB tools in the included 2018 PROSPERO protocols by type of tool. Percentage of total non-Cochrane systematic review protocols on interventions in PROSPERO, by year, for tools for RCT (a), tools for NRS (b), multi-design tools (c), and suites of tools (d). CASP = Critical Appraisal Skills Program; EPHPP = Effective Public Health Practice Project tool; JBI = Joanna Briggs Institute; MINORS = Methodological Index for Non-Randomized Studies; MMAT = Mixed Methods Assessment Tool; NHLBI = National Heart, Lung, and Blood Institute (National Institutes of Health); NOS = Newcastle-Ottawa Scale; NRS = non-randomized studies; PEDro = Physiotherapy Evidence Database; RCT = randomized controlled trial; RoB = risk of bias; ROBINS-I = Risk Of Bias In Non-randomized Studies - of Interventions. Limits: intervention reviews; exclude: Cochrane protocols; restrict to field: assessment of bias