Risk of bias assessment
| Author, year | Was the randomisation sequence adequately generated? | Was allocation adequately concealed? | Was there blinding of participants? | Was there blinding of caregivers? | Was there blinding of data collectors? | Was there blinding of data analyst? | Was there blinding of outcome assessors? | Was loss to follow-up (missing outcome data) infrequent? | Are reports of the study free of suggestion of selective outcome reporting? | Was the study apparently free of other problems that could put it at a risk of bias? |
| Apariman, 200644 | Definitely yes | Probably no | Definitely yes | Probably no | Probably no | Probably no | Probably no | Definitely yes | Probably yes | Probably yes |
| Deng, 200645; Deng, 201046 | Definitely yes | Probably yes | Probably yes | Probably no | Probably no | Probably no | Probably no | Definitely yes | Probably yes | Probably yes |
| Gharabaghi, 201147 | Probably no | Probably no | Definitely yes | Definitely yes | Probably yes | Probably no | Probably yes | Definitely yes | Probably no | Definitely yes |
| Huang, 199648 | Probably yes | Probably yes | Probably yes | Probably no | Probably no | Probably no | Probably no | Definitely yes | Probably yes | Definitely no |
| Nanthakomon, 200649 | Probably yes | Probably yes | Definitely yes | Definitely yes | Probably yes | Probably no | Probably yes | Definitely yes | Probably no | Probably yes |
| Pietri, 199750 | Probably yes | Probably no | Probably yes | Probably yes | Probably no | Probably no | Probably no | Probably no | Probably no | Probably no |
| Safaei, 201751 | Definitely yes | Definitely yes | Definitely yes | Probably yes | Definitely yes | Probably no | Definitely yes | Definitely yes | Probably yes | Definitely yes |
| Wang, 200852 | Definitely yes | Probably yes | Probably yes | Probably no | Probably no | Probably no | Probably no | Definitely yes | Probably yes | Probably no |
| Xie, 200353 | Definitely yes | Probably yes | Definitely yes | Definitely no | Definitely no | Definitely no | Definitely no | Definitely yes | Probably yes | Definitely no |
| Zeraati, 201654 | Definitely yes | Probably yes | Definitely yes | Probably yes | Probably yes | Probably no | Probably no | Definitely yes | Probably yes | Definitely yes |
| Zhou, 200055 | Probably yes | Probably yes | Probably yes | Probably no | Probably no | Probably no | Probably no | Definitely yes | Probably yes | Definitely no |
All answers as: definitely yes (low risk of bias), probably yes, probably no, definitely no (high risk of bias).