The methodological quality of the included trials.

A to L, the 12-item criteria. A, adequate sequence generation; B, concealment of allocation; C, blinding (patient); D, blinding (investigator); E, blinding (assessor); F, incomplete outcome data addressed (ITT analysis); G, incomplete outcome data addressed (drop-outs); H, free of selective reporting; I, similarity at baseline; J, co-interventions constant; K, compliance acceptable; L, timing outcome assessments.
a to e, the Jadad scale. Points were awarded as follows: a, study was described as randomized, 1 point; b, appropriate randomization method, 1 point; c, study described as double-blinded, 1 point; d, appropriate double-blinded method, 1 point; e, description of withdrawals and dropouts, 1 point. The Jadad scale score ranges from 1 to 5; higher scores indicate better quality of the randomized controlled trial (RCT). T total.