Table 2:
Risk of bias for studies included in the systematic review
| Study, year | Domain 1: Study participation | Domain 2: Study attrition | Domain 3: Prognostic factor measurement | Domain 4: Outcome measurement | Domain 5: Study confounding | Domain 6: Statistical analysis and reporting | Overall risk of bias |
|---|---|---|---|---|---|---|---|
| Barnes et al.,21 2008 | High | Low | Low | Low | Moderate | Low | High |
| Moss et al.,1 2008 | Low | Low | Low | Low | Moderate | Low | Moderate |
| Cohen et al.,20 2010 | High | Low | Low | Low | Moderate | Low | High |
| Moss et al.,26 2010 | Moderate | Low | Low | Low | Low | Low | Moderate |
| Da Silva Gane et al.,30 2013 | Low | Low | Low | Low | Moderate | Low | Moderate |
| Pang et al.,22 2013 | Low | Moderate | Low | Low | Moderate | Low | Moderate |
| Reilly et al.,23 2013 | Moderate | Low | Low | Low | Moderate | Low | Moderate |
| Khan et al.,24 2014 | Low | Low | Low | Low | Moderate | Low | Moderate |
| Moroni et al.,25 2014 | Moderate | Low | Low | Low | Low | Low | Moderate |
| Feyi et al.,27 2015 | Low | Low | Low | Moderate | High | Low | High |
| Vick et al.,28 2015 | Moderate | Moderate | Low | Low | Low | Low | Moderate |
| Gerlach et al.,33 2016 | Low | Low | Low | Low | Low | Low | Low |
| Amro et al.,31 2016 | Low | Low | Low | Low | Moderate | Low | Moderate |
| Lefkowits et al.,35 2016 | Low | Low | Low | Low | Low | Low | Low |
| Carmen et al.,32 2016 | Low | Low | Low | Low | Moderate | Low | Moderate |
| Lakin et al.,34 2016 | High | Low | Low | Low | Low | Low | High |
Note: Appendix 1 (available at www.cmaj.ca/lookup/suppl/doi:10.1503.cmaj.160775/-/DC1) provides the details of how judgments were made for the individual domains.