Using the following modified Jadad criteria (Jadad et al., 1996) to provide a relative index of the quality of included studies, the design of each study was evaluated as follows: (1) the study was described as randomized; (2) participants were adequately randomized; (3) the study was described as double blind; (4) the method of double blinding was appropriate; and (5) a description of drop-outs and withdrawals was provided. One point was assigned for each criterion met for a maximum of 5 points. As shown in Table 1, total Jadad scores for included studies ranged from 0 to 3, with a median of 1 (M = 1.23; SD = 0.77). Two independent ratings of Jadad criteria were performed; inter-rater reliability was r = 0.96. Disagreements were resolved through discussion.
