Risk-of-bias assessment of the randomized controlled trials
| Study | Random sequence generation (selection bias) | Allocation concealment (selection bias) | Blinding of participants and personnel (performance bias) | Blinding of outcome assessment (detection bias) | Incomplete outcome data (attrition bias) | Selective reporting (reporting bias) | Other bias |
|---|---|---|---|---|---|---|---|
| Clancy et al.15–17 | High | Unclear | High | Unclear | Unclear | Unclear | Unclear |
| Clancy et al.18–20 | Low | Low | Low | High | Unclear | Unclear | Unclear |
| Cohen et al.21 | High | High | High | Unclear | Unclear | Unclear | Unclear |
| Edelman et al.22 | Low | Low | Low | Low | Low | Low | Unclear |
| Naik et al.23 | Low | Low | Unclear | High | Low | Unclear | Unclear |
| Rygg et al.,24 | Low | Low | Low | Unclear | Low | Unclear | Unclear |
| Sadur et al.25 | High | High | High | Unclear | Unclear | Unclear | Unclear |
| Schillinger et al.26 | Low | High | High | Unclear | Low | Unclear | Unclear |
| Taveira et al.27 | High | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear |
| Taveira et al.28 | High | High | Unclear | High | Low | Unclear | Unclear |
| Trento et al.29–31 | Low | Unclear | Low | Unclear | Low | Unclear | Unclear |
| Trento et al.32 | High | High | High | Unclear | Unclear | Unclear | Unclear |
| Wagner et al.33 | High | High | High | Unclear | Unclear | High | Unclear |