Risk of bias
| Study/risk area | Mills and Allen31 | Grossmann et al 30 | Bogosian et al 28 | Kolahkaj & Zargar29 | Amiri et al 25 | Mahdavi et al 26 | Nejati et al 27 | Bahrani et al 23 | Simpson et al 22 | Carletto et al 24 | Cavelera et al 32 | Senders et al 21 |
| Random sequence generation (selection bias) | Unclear | Low | Low | Low | Unclear | Unclear | Low | Low | Low | Low | Low | Low |
| Allocation concealment (selection bias) | Unclear | Low | Low | Unclear | Unclear | Unclear | Unclear | Low | Low | Low | Unclear | Low |
| Blinding of assessors (performance bias) | Unclear | Low | Low | Unclear | Unclear | Unclear | Unclear | Low | Low | Low | Unclear | Low |
| Blinding of outcome assessment (detection bias) (patient reported outcomes) | High | Low | Low | Unclear | Unclear | Unclear | Unclear | Low | Low | Low | Unclear | Low |
| Incomplete outcome data addressed (attrition bias) | Unclear | Low | Low | High | High | Unclear | Unclear | Unclear | Low | Low | Unclear | Low |
| Selective outcome reporting (reporting bias) | High | Low | Low | Low | Low | Low | Low | Low | Low | Low | Low | Low |
| Other sources of bias (ie, baseline bias) | Unclear | Low | Low | High | Unclear | High | High | Low | Low | Low | Low | Low |
| Overall risk of bias | High | Low | Low | High | High | High | High | Unclear | Low | Low | Unclear | Low |