| References | Risk of bias domainsa | Tierb | |||||
|---|---|---|---|---|---|---|---|
| Confounding(a) | Attrition | Exposure | Outcome | Reporting | Statistics | ||
| Devine et al. (1995) | + | − | − | ++ | ++ | ++ | 2 |
| Ilich et al. (2010) | ++ | + | + | ++ | + | + | 1 |
a
Expert judgement was translated into a rating scale for each question to be answered as follows: (++): definitely low RoB; (+): probably low RoB; (NR): not reported; (−): probably high RoB; (−−): definitively high RoB.
b
The individual rating for each question was combined by an algorithm and translated to an overall tier of reliability for each individual study (RoB tier 1: low RoB; RoB tier 2: moderate RoB; RoB tier 3: high RoB).