- Newcastle Ottawa Scale Rating of included studies
| Included study | Selection of subjects | Outcome of measurement | Total score | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Representativeness of the exposed cohort | Representativeness of the control cohort | Ascertainment of the exposure | Lack of observatory indicator for the outcome of the study | Comparability between exposed and control cohorts | Independent evaluation of blinding | Sufficiency of follow-up | Completeness of follow-up | ||
| Geng et al (16) | 1 | 1 | 1 | 1 | 2 | 0 | 1 | 1 | 8 |
| Takahashi et al(17) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Zhao et al(18) | 1 | 1 | 1 | 1 | 2 | 0 | 1 | 1 | 8 |
| Lee et al(19) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
| Wang et al(20) | 1 | 1 | 1 | 1 | 2 | 0 | 1 | 1 | 8 |
| Kushiyama et al(21) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |