Table 1.
Example of NOS for assessment of quality of included studies-cross-sectional studies (1 indicates individual criterion within the subsection was fulfilled)
| Quality assessment criteria | White et al. [23] | Waterland et al. [24] | Ezzie et al. [25] | Kohli et al. [26] |
|---|---|---|---|---|
| Selection (maximum 4) | ||||
| Case definition adequate | 1 | 1 | 1 | 1 |
| Representativeness of the cases | 1 | 1 | 1 | 1 |
| Selection of controls | 1 | 1 | 1 | 1 |
| Definition of controls | 1 | 1 | 0 | 1 |
| Comparability (maximum 2) | ||||
| Comparability of cohorts on the basis of the design of analysis (controls used) | 1 | 1 | 1 | 1 |
| Confounding factors are controlled. | 1 | 1 | 1 | 1 |
| Exposure (maximum 3) | ||||
| Ascertainment of exposure | 1 | 1 | 1 | 1 |
| Same method cases and controls? | 1 | 1 | 1 | 1 |
| Non-response rate | 0 | 1 | 0 | 0 |
| Overall quality score (maximum 9) | 8 | 9 | 7 | 8 |