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. 2013 Nov 1;13(23):1–45.

Table 4. Body of Evidence Examined According to Study Design.

Study Design Number of Eligible Studies
Question 1 Question 2 Question 3
RCT studies
Systematic review of RCTs - 4 -
Large RCT (N > 100) - - -
Small RCT (N < 100) - - 3
Observational studies
Systematic review of non-RCTs with contemporaneous controls 7 - -
Non-RCT with non-contemporaneous controls - - -
Systematic review of non-RCTs with historical controls - - -
Non-RCT with historical controls - - -
Longitudinal cohort study 11    
Database, registry, or cross-sectional study - - -
Case series - - -
Retrospective review, modelling - - -
Studies presented at an international conference - - -
Expert opinion - - -
Total 18 4 3

Abbreviation: RCT, randomized controlled trial.