Risk of bias
| Study | Bias from confounding | Bias from selection of participants | Bias from measurement of outcomes | Bias from measurement of exposure | Bias from selection of reported result | Bias from missing data | Overall risk of bias |
|---|---|---|---|---|---|---|---|
| Aljohani et al. (20) | Low | Low | Low | Moderate | Low | Unclear | Unclear |
| Barnabe et al. (21) | Moderate | Low | Low | Moderate | Low | Unclear | Unclear |
| Bresee et al. (22) | Low | Low | Low | Moderate | Low | Low | Moderate |
| Callegari et al. (23) | Serious | Low | Low | Unclear | Low | Unclear | Unclear |
| Cohen et al. (24) | Moderate | Low | Low | Moderate | Low | Unclear | Unclear |
| Dyck et al. (25) | Serious | Low | Serious | Moderate | Low | Unclear | Unclear |
| Goulet et al. (26) | Moderate | Low | Low | Moderate | Low | Unclear | Unclear |
| Hong et al. (27) | Moderate | Low | Low | Low | Low | Low | Moderate |
| Leslie et al. (28) | Low | Low | Low | Moderate | Low | Low | Moderate |
| Liu et al. (29) | Low | Moderate | Low | Serious | Low | Unclear | Unclear |
| Martens et al. (30) | Low | Moderate | Low | Moderate | Low | Unclear | Unclear |
| McIntyre et al. (31) | Low | Moderate | Low | Low | Low | Low | Moderate |
| Meatherall, (32) | Serious | Unclear | Serious | Unclear | Low | Unclear | Unclear |
| Oster et al. (33) | Moderate | Low | Low | Moderate | Low | Low | Moderate |
| Promislow et al. (34) | Low | Low | Low | Low | Low | Low | Low |
| Riddell et al. (35) | Low | Low | Low | Moderate | Low | Low | Moderate |
| Rose et al. (36) | Low | Moderate | Low | Unclear | Low | Unclear | Unclear |
| Roy et al. (37) | Serious | Moderate | Low | Unclear | Low | Unclear | Unclear |
| Shen et al. (38) | Moderate | Serious | Low | Moderate | Low | Low | Serious |
| Sood et al. (39) | Low | Low | Low | Low | Low | Low | Low |
| Storsely et al. (40) | Moderate | Low | Low | Low | Low | Low | Moderate |
| Tonelli (41) | Low | Low | Moderate | Low | Low | Moderate | Moderate |
| Tonelli et al. (42) | Moderate | Low | Low | Low | Low | Low | Moderate |
| Weber et al. (43) | Low | Low | Low | Low | Low | Low | Low |
| Wei-Randall et al. (44) | Serious | Low | Low | Serious | Low | Moderate | Serious |
| Yeates (45) | Low | Low | Low | Low | Low | Low | Low |
| Yeates (46) | Low | Low | Low | Low | Low | Low | Low |
| Zhang et al. (47) | Serious | Low | Low | Low | Low | Unclear | Unclear |