Table 3.
Risk of bias in included studies
| Risk of bias domain | Roncin et al,15 1996 | Gertsch et al,16 2002 | Gertsch et al,17 2004 | Chow et al,18 2005 | Moraga et al,13 2007 | Leadbetter et al,19 2009 |
| Random-sequence generation (selection bias) | Unclear | Unclear | Low | Low | Low | Low |
| Allocation concealment (selection bias) | Unclear | Low | Low | Low | Unclear | Low |
| Blinding of participants (performance bias) | High | Low | Low | Low | High | Low |
| Blinding of outcome assessment (detection bias) | High | Low | Low | Low | High | Low |
| Incomplete outcome data (attrition bias) | High | High | Low | Low | Low | Low |
| Selective outcome reporting (reporting bias) | Low | Low | Low | Low | Low | Low |
| Other source of bias | High | Low | High | Low | High | Low |
| Overall risk of bias | High | High | Low | Low | High | Low |