Table 2.
Results of quality assessment by the Newcastle–Ottawa Scale
| Study | Selection |
Comparability |
Exposure |
Total | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Adequate definition of cases | Representativeness of cases | Selection of controls | Definition of controls | Control for important factor | Control for additional factor | Ascertainment of exposure | Same method to ascertain | Non-response rate | ||
| Verrotti et al1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 7 |
| Karabiber et al2 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 6 |
| Sener et al3 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 6 |
| Vurucu et al7 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 6 |
| Kurul et al12 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 7 |
| Yildiz et al10 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 7 |
| Belcastro et al11 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 7 |
| Chuang et al4 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 7 |