Fig. 2

Risk of bias analysis. Risk of bias for each outcome variable was rated as high ( ×), low ( +), or some concerns (-) across five domains — randomisation, protocol deviation, missing data, measurement, and reporting — using the Cochrane Risk of Bias 2 (RoB2) tool. The overall risk of bias for each study was determined as: “Low” if the trial was judged to be at low risk of bias for all domains; “Some concerns” if the trial was judged to raise some concerns in at least one domain but not to be at high risk of bias for any domain; or “High” if the trial was judged to be at high risk of bias in at least one domain or if the trial was judged to have “some concerns” for multiple domains. The figure was built using the robvis R package [19]