Two authors (H. Z. and Z. L.) independently reviewed all
studies to determine if they met the inclusion and exclusion criteria and to rate the quality of the included studies.
If there was disagreement, consensus was reached
through discussion. If consensus was not reached a third
author was consulted (H. W.) and the decision of two of
the three authors was adopted. Two authors (H. Z. and Z.
L.) independently extracted the data from the studies
selected for meta-analysis. Information included the location of study, recruitment strategies, study design, participants’ characteristics, intervention (e.g. type, content,
intensity, duration, and follow up), and outcomes. If there
was disagreement during data extraction, a third author
(H. W.) was approached and consensus was reached
through discussion. The reviewers also contacted three
authors of studies for missing outcome data.
The Jadad scale was used to assess the methodological
quality of the included studies because there is no consensus on a gold standard to evaluate the internal validity
or methodological quality of an RCT. Accordingly, the
selection of the Jadad scale has relative merit because it
assesses the most important individual components of
methodological quality by using a simple approach. This
nominal scale addresses three essential questions and two
other questions