Table 4.
Risk of bias assessment of the included studies
| Risk of bias | Lebrec et al[10] | Rössle et al[9] | Ginés et al[8] | Sanyal et al[11] | Salerno et al[12] | Narahara et al[13] |
| Generation of random allocation sequence (risk) | NR (unclear) | NR (unclear) | NR (unclear) | NR (unclear) | NR (unclear) | NR (unclear) |
| Concealment of allocation sequence (risk) | Sealed opaque envelopes (low) | NR (unclear) | Sealed opaque envelopes (low) | Sealed opaque envelopes (low) | Sealed opaque envelopes (low) | Sealed opaque envelopes (low) |
| Blinding of participants and personnel (risk) | Unblinded (high) | Unblinded (high) | Unblinded (high) | Unblinded (high) | Unblinded (high) | Unblinded (high) |
| Blinding of outcome assessment (risk) | Unblinded (high) | Unblinded (high) | Unblinded (high) | Unblinded (high) | Unblinded (high) | Unblinded (high) |
| Incomplete outcome data (risk) | Intention-to-treat analysis, description of drop-outs (low) | Intention-to-treat analysis, description of drop-outs (low) | Intention-to-treat analysis, description of drop-outs (low) | Intention-to-treat analysis, description of drop-outs (low) | Intention-to-treat analysis, description of drop-outs (low) | Intention-to-treat analysis, description of drop-outs (low) |
| Selective outcome reporting (risk) | All of the outcomes in the methods section were reported in the results section (low) | All of the outcomes in the methods section were reported in the results section (low) | All of the outcomes in the methods section were reported in the results section (low) | All of the outcomes in the methods section were reported in the results section (low) | All of the outcomes in the methods section were reported in the results section (low) | All of the outcomes in the methods section were reported in the results section (low) |
NR: Not reported.