D1, Bias arising from the randomisation process; D2, Bias due to deviations from intended interventions; D3, Bias due to missing outcome data; D4, Bias in measurement of the outcome; D5, Bias in selection of the reported result; Q1, Adequate definition of case; Q2, Representativeness of cases; Q3, Selection of control; Q4, Definition of control; Q5, Study controls for important factor or additional factor; Q6, Ascertainment of exposure; Q7, Same method of ascertainment for cases and controls; Q8, Non-response rate.

RCT, randomized controlled trial; RoB2, risk of bias 2; NOS, Newcastle-Ottawa Scale.