Table 3.
Study quality and bias in the retrospective cohort studies assessed via the Newcastle-Ottawa Scale checklist
| Study |
Cohort selection |
Comparability |
Outcome ascertainment |
|||||
| Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertain-ment of exposure | Demonstration that outcome of interest was not present at start of study | Comparability of cases and controls on the basis of the design or analysis | Assessment of outcome | Was follow-up long enough for outcomes to occur | Adequacy of follow up of cohorts | |
| Cai et al[10], 2018 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |
| Zhong et al[30], 2018 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |
| Li et al[18], 2018 | 1 | 1 | 1 | 1 | 2 | 1 | 0 | 0 |
| Weng et al[22], 2018 | 1 | 1 | 1 | 1 | 2 | 1 | 0 | 0 |
| Chen et al[11], 2018 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Gong et al[14], 2018 | 1 | 1 | 1 | 1 | 2 | 1 | 0 | 0 |
| Yu et al[26], 2018 | 1 | 1 | 1 | 1 | 2 | 1 | 0 | 0 |
| Huang et al[17], 2017 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Han et al[16], 2017 | 1 | 1 | 1 | 1 | 2 | 1 | 0 | 0 |
| Guo et al[15], 2017 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |
| Zhang et al[27], 2018 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |