Table 2.
Study quality assessment using Newcastle–Ottawa scale for case–control studies
| References | Selection | Comparability of cohorts | Ascertainment of exposure | Outcomes | Non response rate | NOS score | |||
|---|---|---|---|---|---|---|---|---|---|
| Adequate case definition | Representativeness of cases | Selection of controls | Definition of controls | Same method of ascertainment | |||||
| El Maghraoui [10] | * | – | * | * | * | * | * | – | 6 |
| Kao [11] | * | * | – | * | * | * | – | – | 5 |
| Merle B [14] | * | – | * | * | * | * | * | – | 6 |
| Neto [15] | * | * | * | * | ** | * | * | – | 8 |
| Sahin [16] | * | – | * | – | * | * | * | – | 5 |
| Sahin [17] | * | * | * | * | * | * | * | * | 8 |
| Yurdakul [18] | * | * | * | – | – | * | * | – | 5 |
| Røren Nordén [19] | * | * | * | * | * | * | * | * | 8 |
| Marcora [20] | * | * | * | * | ** | * | * | * | 9 |
| Dos Santos [12] | * | – | * | – | * | * | * | – | 5 |
| Toussirot [13] | * | * | * | – | * | * | * | * | 7 |
*Each asterisk represents if individual criterion within the subsection was fulfilled
NOS Newcastle–Ottawa quality assessment scale