Table 2.
Quality assessment of the included studies using the Newcastle–Ottawa Scale (NOS).
| References | Representativeness of the exposed group | Selection of non-exposed groups | Determination of exposure factors | Identification of outcome indicators not yet to be observed at study entry | Comparability of exposed and unexposed groups considered in design and statistical analysis | Design and statistical analysis | Adequacy of the study's evaluation of the outcome | Adequacy of follow-up in exposed and unexposed groups | Total scores |
|---|---|---|---|---|---|---|---|---|---|
| Cohort study | |||||||||
| Abdelrazeq et al. (16) | * | * | * | * | ** | * | * | * | 9 |
| Akiyama et al. (17) | * | * | * | / | ** | * | * | * | 8 |
| Baek et al. (18) | * | * | * | / | ** | * | * | * | 8 |
| Barnes et al. (19) | * | * | * | * | ** | * | * | * | 9 |
| Ferrante et al. (21) | * | * | * | * | ** | * | * | * | 9 |
| Fleshner et al. (22) | * | * | * | / | * | * | * | * | 7 |
| Gorrepati et al. (23) | * | * | * | / | ** | * | * | * | 8 |
| Hashavia et al. (24) | * | * | * | / | * | * | * | * | 7 |
| Hata et al. (26) | * | * | * | / | ** | * | * | * | 8 |
| Hata et al. (25) | * | * | * | / | * | * | * | * | 7 |
| Kasashima et al. (27) | * | * | * | * | ** | * | * | * | 9 |
| Okita et al. (28) | * | * | * | / | * | * | * | * | 7 |
| References | Is the case definition adequate? | Representativeness of the cases | Determination of control group | Definition of controls | Comparability of cases and controls based on the design or analysis | Ascertainment of exposure | Same method of ascertainment for cases and controls | Non response | Total scores |
| Case control | |||||||||
| Bertucci Zoccali et al. (20) | * | * | * | * | ** | * | * | * | 9 |
* one score, ** two score.