Methodological quality appraisal of the studies
| Study references | Methodological items | Score (%) | Adjusted analysis | Quality | |||||||||||||||||||
| 1 | 2 | 3 | 3A | 3B | 4 | 5 | 6 | 7 | 8 | 8A | 9 | 10 | 11 | 12 | 12A | 13 | 14 | 15 | 15A | ||||
| Prospective/retrospective cohort studies | |||||||||||||||||||||||
| Tüchsen et al35 | + | – | – | +* | – | + | NA | NA | + | + | – | + | – | + | + | +* | + | 67 | Yes | High | |||
| Tüchsen et al36 | + | + | – | + | – | +* | NA | NA | + | + | – | + | – | + | + | ? | + | 67 | Yes | High | |||
| Angersbach et al37 | + | – | + | – | NA | NA | + | + | + | + | – | – | – | + | – | NA | – | 50 | No | Low | |||
| Case-control studies | |||||||||||||||||||||||
| Kleiven et al38 | + | + | + | + | – | + | + | NA | NA | + | + | – | – | – | + | + | + | + | + | 76 | Yes | High | |
| Bourbonnais et al39 | – | + | + | + | – | – | + | NA | NA | + | + | – | – | – | + | – | + | + | + | 59 | Yes | High | |
| Cross-sectional studies | |||||||||||||||||||||||
| Higashi et al40 | + | + | + | + | + | NA | NA | + | – | – | – | + | – | NA | + | 67 | Yes | High | |||||
| Niedhammer et al41 | + | + | + | – | +† | NA | NA | – | – | – | – | + | + | + | + | 62 | Yes | High | |||||
| Böckerman and Laukkanen42 | + | + | – | – | +* | NA | NA | – | – | – | – | + | + | +* | + | 54 | Yes | High | |||||
| Ohayon et al43 | + | + | – | + | + | NA | NA | – | – | – | – | + | – | + | + | 54 | Yes | High | |||||
| Eyal et al44 | + | + | ?‡ | – | + | NA | NA | + | – | – | – | + | – | + | + | 54 | Yes | High | |||||
| Chan et al45 | + | + | + | NA | NA | + | + | + | + | – | – | + | – | NA | + | 75 | No | Low | |||||
| Koller46 | + | + | + | + | + | NA | NA | – | + | – | – | + | – | NA | + | 67 | No | Low | |||||
| Smith et al47 | + | + | + | – | + | NA | NA | + | – | – | – | NA | – | NA | + | 55 | No | Low | |||||
| Colligan et al48 | + | + | + | – | + | NA | NA | + | – | – | – | + | – | NA | – | 50 | No | Low | |||||
| Drake et al49 | + | + | – | – | + | NA | NA | + | – | – | – | + | – | NA | + | 50 | No | Low | |||||
| Chee and Rampal50 | + | + | –* | – | +* | + | +* | – | – | – | – | NA | – | NA | + | 46 | No | Low | |||||
| Lambert et al51 | + | + | – | – | – | NA | NA | – | – | + | – | + | – | + | + | 46 | No | Low | |||||
| Olsen and Dahl52 | + | – | – | – | +† | NA | NA | – | – | – | – | + | + | + | + | 46 | No | Low | |||||
| Jamal and Baba53 | – | + | – | + | + | NA | NA | + | – | – | – | + | – | NA | – | 42 | No | Low | |||||
| Sveinsdottir54 | + | + | – | – | + | NA | NA | – | – | – | – | + | – | NA | + | 42 | No | Low | |||||
| Demerouti et al55 | + | + | – | + | –* | NA | NA | – | – | – | – | + | – | + | – | 38 | No | Low | |||||
| Aguirre and Foret56 | + | + | ?‡ | + | – | NA | NA | – | + | – | – | – | – | NA | + | 42 | No | Low | |||||
| Drago and Wooden57 | + | + | – | – | – | NA | NA | – | – | – | – | + | – | + | + | 38 | No | Low | |||||
| Fawer and Lob58 | – | – | + | – | – | NA | NA | – | – | – | – | NA | – | NA | + | 18 | No | Low | |||||