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 doubleblinding 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 sco