Figure 1.

Summary of risk of bias assessment for randomized controlled trials (n = 10). Selection bias (random sequence generation, low risk (n = 2), unclear risk (n = 8) + allocation concealment, low risk (n = 4), unclear risk (n = 6)); Performance bias (blinding of participants and researchers, low risk (n = 3), unclear risk (n = 7)); Detection bias (blinding of outcome assessment, low risk (n = 4), unclear risk (n = 6)); Attrition bias (incomplete outcome data, low risk (n = 9), unclear risk (n = 1)); Reporting bias (selective reporting, low risk (n = 10)); Other bias, low risk (n = 10).