Study Quality Assessment
Two reviewers (AN, SS) independently assessed the quality of included trials using a validated quality scale that is based on the methods used to generate the randomization sequence, the method of double-blinding and the description of patient withdrawals and dropouts. They scored the appropriateness of randomization and double blinding from 0 to 2 points, and the reporting of withdrawals and dropouts, as 0 or 1 point, for a maximum of 5 points if all criteria were satisfied. Studies with a score > 2 were considered high quality; studies with a score of ≤ 2 were considered low quality. Interrater agreement about the assessment of the quality of included
trials was moderate (κ = 0.58, 95% confidence interval [CI]: 0.21–0.95). Disagreements about the quality of the studies were resolved by consensus between the reviewers.