Table 3.
Methodological quality of case-control study using Newcastle-Ottawa Quality Assessment Scale.
| Study year | Selection | Comparability | Exposure | Total | |||||
|---|---|---|---|---|---|---|---|---|---|
| Adequacy of case definition | Representativeness of case | Selection of controls | Definition of controls | Comparability of groups | Assessment of exposure | Methods of ascertainment/follow-up | Loss to follow-up/nonresponse rate | ||
| Sorkhabi 2015 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
| Lema 2009 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 6 |
| Lema 2008 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 6 |
| Lema 2005 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
For each item, star rating: a maximum of one star for each numbered item within the selection and exposure categories. A maximum of two stars can be given for comparability.