Risk of bias
| Bias | Gilles et al18 | Swain et al19 | Gill et al20 | Chester et al21 | Chu et al22 |
|---|---|---|---|---|---|
| Random sequence generation (selection bias) | Low risk ‘randomly assigned’ | Low risk ‘randomised using block scheme’ | Low risk ‘randomly assigned’ | Low risk ‘Latin square design for subject assignment’ | Low risk ‘randomised’ |
| Allocation concealment (selection bias) | Unclear risk Not addressed | Unclear risk Not addressed | Unclear risk Not addressed | Unclear risk Not addressed | Unclear risk Not addressed |
| Blinding (performance bias and detection bias) All outcomes—patients? | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ |
| Blinding (performance bias and detection bias) All outcomes—providers? | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘condition allocation was carried out by associate not involved in study’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ |
| Blinding (performance bias and detection bias) All outcomes—outcome assessors? | Unclear risk Not addressed | Unclear risk Not addressed | Low risk ‘double-blind’ | Unclear risk Not addressed | Unclear risk Not addressed |
| Incomplete outcome data (attrition bias) All outcomes—dropouts? | Low risk No dropouts | Low risk No dropouts | Low risk No dropouts | Low risk No dropouts | Low risk 1 drop out, addressed and justified |
| Incomplete outcome data (attrition bias) All outcomes—ITT analysis? | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported |
| Selective reporting (reporting bias) | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported |
| Similarity of baseline characteristics? | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics |
| Co-intervention avoided or similar? | Low risk No co-interventions | Low risk No co-interventions | Low risk Cross-over with adequate washout period | Low risk No co-interventions | Low risk Cross-over with adequate washout period |
| Compliance acceptable? | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable |
| Timing outcome assessments similar? | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups |
| Overall impression | Low risk | Low risk | Low risk | Low risk | Low risk |
| Bias | Hodges et al23 | Hodges et al24 | Pritchard-Peschek et al25 | Berry26 | Pritchard-Peschek et al27 |
| Random sequence generation (selection bias) | Low risk ‘randomly assigned’ | Low risk ‘randomised’ | Low risk ‘randomly assigned’ | Low risk ‘random trial’ | Low risk ‘randomised’ |
| Allocation concealment (selection bias) | Unclear risk Not addressed | Unclear risk Not addressed | Unclear risk Not addressed | Low risk ‘member placed capsules in 2 different envelopes marked A or B, known only to this member’ | Unclear risk Not addressed |
| Blinding (performance bias and detection bias) All outcomes—patients? | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ |
| Blinding (performance bias and detection bias) All outcomes—providers? | Low risk ‘double-blind’ | Low risk ‘double-blind’ | Low risk ‘double-blind’ | High risk ‘known to member of research team’ assigning the envelopes A or B | Low risk ‘double-blind’ |
| Blinding (performance bias and detection bias) All outcomes—outcome assessors? | Unclear risk Not addressed | Unclear risk Not addressed | Unclear risk Not addressed | Low risk ‘double-blind’ | Unclear risk Not addressed |
| Incomplete outcome data (attrition bias) All outcomes—drop-outs? | Low risk No dropouts | High risk 1 out, not addressed nor justified | Low risk No dropouts | Low risk 2 dropouts, addressed and justified | Low risk No dropouts |
| Incomplete outcome data All outcomes—ITT analysis? | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported |
| Selective reporting (reporting bias) | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported | Low risk All prespecified outcomes reported |
| Similarity of baseline characteristics? | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics | Low risk No significant differences among baseline characteristics |
| Co-intervention avoided or similar? | Low risk Cross-over with adequate washout period | Low risk Cross-over with adequate washout period | Low risk Cross-over with adequate washout period | Low risk Cross-over with adequate washout period | Low risk Cross-over with adequate washout period |
| Compliance acceptable? | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable | Low risk Compliance with interventions acceptable |
| Timing outcome assessments similar? | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups | Low risk Outcomes measured at same time across groups |
| Overall impression | Low risk | Low risk | Low risk | Low risk | Low risk |
ITT, intention to treat.