Table 2.
Risk of bias in included cohort studies
| Study and Year (Reference) | Representative Cohort | Selection of Nonexposed | Exposure Ascertained | Not Present at Outset | Comparability | Outcome Assessment | Duration of Follow-Up | Adequacy of Follow-Up |
|---|---|---|---|---|---|---|---|---|
| Lodise et al. 2008 (35) | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 |
| Davies et al. 2013 (36) | 1 | 1 | 1 | 0 | 2 | 1 | 1 | 0 |
| Chan et al. 2011 (38) | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 |
| Peyrani et al. 2014 (39) | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 |
| Fujii et al. 2013 (37) | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Rodriguez Colomo et al. 2011 (34) | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 |
The Newcastle–Ottawa Scales were used to assess risk of bias for the cohort studies. Each domain was rated on a scale of zero or one star, except comparability, which can be awarded up to two stars. 0, High or unclear risk of bias; 1 or 2, low risk of bias.