Table 2.
Risk of bias assessment for included studies
| Study | Data acquisition | Study participation | Study attrition | Prognostic factor measurement | Outcome measurement | Study confounding | Statistical analysis and presentation |
|---|---|---|---|---|---|---|---|
| Arenal et al.20 | Retrospective | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| Cook et al.9 | Prospective | Low | Low | Moderate | Low | Moderate | Moderate |
| Fukuda et al.21 | Retrospective | Moderate | Low | Moderate | Moderate | Moderate | Moderate |
| Kwok et al.23 | Prospective | Moderate | Moderate | Moderate | Low | Low | Moderate |
| Leong et al.22 | Retrospective | Low | Low | Moderate | Moderate | High | Moderate |
| McGillicuddy et al.24 | Retrospective | Low | Low | Moderate | Moderate | Moderate | High |
| Modini et al.25 | Retrospective | Low | Low | Moderate | Low | Moderate | Low |
| Okubo et al.26 | Retrospective | Low | Low | Low | Low | Low | Low |
| Vaughan-Shaw et al.27 | Retrospective | Low | Low | Low | Low | Low | Low |