Results of the risk of bias assessment
| Study ID | Reporting | External validity | Internal validity—bias | Internal validity— confounding | Total |
|---|---|---|---|---|---|
| Ament et al22 | Unclear | High | High | High | High |
| Benenson et al23 | Unclear | High | High | High | High |
| Cates24 | High | Unclear | High | High | High |
| Enriquez-Puga et al25 | Unclear | High | High | Unclear | High |
| Forsner et al26 | Unclear | Low | High | High | High |
| Gerber et al35 | Low | Low | High | High | High |
| Higuchi et al27 | High | High | High | High | High |
| Kelly28 | High | High | High | High | High |
| Knops et al29 | High | Low | High | High | High |
| Loszadi et al30 | Unclear | High | Unclear | High | High |
| McLaws et al31 | High | Low | Unclear | High | High |
| Stéphan et al32 | High | High | Unclear | High | High |
| Wakefield et al33 | High | High | High | High | High |
| Williams et al34 | High | High | Unclear | High | High |
| Total | High | High | High | High | High |