Table 1 Risk of bias
Study | Selection bias | Allocation concealment bias | Performance bias | Detection bias | Attrition bias | Selective reporting | Other bias | Overall risk |
|---|---|---|---|---|---|---|---|---|
McCowan et al.28 | No | No | No | Unclear: blinding of outcome assessors not detailed | Yes: attrition rate variation was not fully explained. No intention-to-treat analysis | Unclear: no protocol | No | C-High |
Eccles et al.29 | No | No | No | No | No | No | No | A-Low |
Zeiger et al.30 | No | No | No | No | No | No | No | A-Low |
Tamblyn et al.31 | No | No | No | No | No | No | No | A-Low |
