TABLE A2.
Risk of bias assessment a of the studies with case‐control design
| Selection | Outcome | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Author, year | Adequacy case definition | Representativeness cases | Selection of controls | Definition of controls | Comparability of cases and controls on the basis of design or analysis | Ascertainment of exposure | Same method ascertainment cases and controls | Non‐response rate | Final score |
| Boillat‐Blanco et al. (2016) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Senkoro et al. (2016) | 1 | 1 | 1 | 1 | 2 | 0 | 1 | 0 | 7 |
| Haraldsdottir et al. (2015) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 8 |
| Faurholt‐Jepsen et al. (2011) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 1 | 9 |
a
Quality assessment was performed using the Newcastle‐Ottawa scale for case‐control studies. For the questions concerning selection and outcome, 1 point is assigned when adequate and 0 points if not. For the question on comparability of cohorts, a maximum of 2 points can be assigned.