Table 2.
Results of methodological quality assessment.
| Study | Study design | Reporting | Ext. validity | Int. validity - bias | Int. validity—confounding | Power |
Total score |
Grade | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | ||||
| Cappellini et al. (2016) | Cross-sectional | 1 | 1 | 1 | 1 | 1 | 0 | 0* | 0* | 1 | 1 | 1 | 1 | 0* | 0 | 9 | Fair | |||||||||||||
| Cappellini et al. (2018) | Cross-sectional | 1 | 1 | 1 | 1 | 1 | 0 | 0* | 0* | 1 | 1 | 1 | 1 | 0* | 0 | 9 | Fair | |||||||||||||
| Goudriaan et al. (2018) | Cross-sectional | 1 | 1 | 1 | 1 | 1 | 0 | 0* | 0* | 1 | 1 | 1 | 1 | 0* | 1 | 10 | Good | |||||||||||||
| Hashiguchi et al. (2018) | Cross-sectional | 1 | 1 | 1 | 1 | 1 | 0 | 0* | 0* | 1 | 1 | 1 | 1 | 0* | 0 | 9 | Fair | |||||||||||||
| Kim Y. et al. (2018) | Cross-sectional | 1 | 1 | 1 | 1 | 1 | 1 | 0* | 0* | 1 | 1 | 1 | 0* | 0* | 0 | 9 | Fair | |||||||||||||
| Tang et al. (2015) | Cross-sectional | 1 | 1 | 1 | 1 | 1 | 0 | 0* | 0* | 1 | 1 | 1 | 0* | 0* | 0 | 8 | Fair | |||||||||||||
| Torricelli et al. (2014) | Cross-sectional | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0* | 0* | 0 | 5 | Poor | |||||||||||||
| Yu et al. (2019) | Cross-sectional | 1 | 1 | 1 | 1 | 1 | 1 | 0* | 0* | 1 | 1 | 1 | 0* | 0* | 0 | 9 | Fair | |||||||||||||
| Shuman et al. (2016) | Case-control | 1 | 1 | 0 | 1 | 1 | 1 | 0* | 0* | 1 | 0 | 1 | 1 | 0* | 0* | 0 | 8 | Fair | ||||||||||||
| Shuman et al. (2017) | Case-control | 1 | 1 | 1 | 1 | 1 | 0 | 0* | 1 | 1 | 0* | 1 | 1 | 1 | 0* | 0 | 10 | Good | ||||||||||||
| Steele et al. (2015) | Case-control | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0* | 1 | 1 | 1 | 1 | 0 | 12 | Good | ||||||||||||
| Steele et al. (2019) | Case-control | 1 | 1 | 0 | 1 | 1 | 0 | 0* | 0* | 1 | 1 | 1 | 1 | 1 | 0* | 0 | 9 | Fair | ||||||||||||
| Schwartz et al. (2016) | Retrospective cohort |
1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 13 | Excellent | ||||||||||||
| Shuman et al. (2018) | Retrospective cohort |
1 | 1 | 1 | 1 | 1 | 0 | 0 | 0* | 1 | 0* | 1 | 1 | 1 | 0* | 0 | 9 | Fair | ||||||||||||
| Shuman et al. (2019) | Retrospective cohort |
1 | 1 | 0 | 1 | 1 | 1 | 0* | 0* | 1 | 0* | 1 | 1 | 1 | 0* | 0 | 9 | Fair | ||||||||||||
| Oudenhoven et al. (2019) | Retrospective cohort |
1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 13 | Excellent | ||||||||||||
1: yes; 0:no; 0*: unable to determine; Ext.: external; Int.: internal; maximum total scores: cross-sectional = 14; case-control and cohort = 15.