Table 2.
Risk of bias summary
| 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 |
|---|---|---|---|---|---|---|---|
| Shiina 2010 | low | Unclear | Low | Low | Low | Low | Unclear |
| Noroozian 2013 | low | unclear | Low | Low | Low | Low | Unclear |
| Umbricht 2014 | low | Low | Low | low | Low | Low | Unclear |
| Keefe 2015 | low | unclear | low | unclear | low | low | Unclear |
| Haig 2016 | low | low | low | low | unclear | low | Low |
| Jeon 2016 | low | Unclear | Low | Low | Low | Low | Low |
| Smith 2016 | low | Unclear | Low | Low | Low | Low | Unclear |
| Walliing 2016 | low | unclear | low | low | low | low | unclear |