Table 2.
Newcastle-Ottawa Scale for Assessment of Quality of Included Studies
| Quality Assessment Criteria | Wigg et al17 | Farhadi et al18 | Miele et al19 | Volynets et al20 | Giorgio et al21 |
|---|---|---|---|---|---|
| Is the case definition adequate? (Yes, with independent validation) | + | + | + | + | + |
| Representatives of cases? (Consecutive or obviously representative series of cases) | + | − | + | − | + |
| Selection of controls? (Community controls) | + | + | + | − | + |
| Definition of controls? (No history of studied end point) | + | + | + | + | + |
| Study controls for age/sex? (Matching or multivariable analysis) | + | − | + | − | + |
| Study controls for at least three additional factors? | − | − | − | − | − |
| Ascertainment of exposure? (Secure record, structured interview by health-care practitioner, blind to case/control status) | + | + | + | + | + |
| Same method of ascertainment of cases/controls? (Yes) | − | + | + | + | + |
| Nonresponse rate? (Same for both groups) | − | + | + | + | + |
| Total overall score (Maximum = 9) | 6 | 6 | 8 | 5 | 8 |