Table 3.
Risk of bias for cohort and case-control studies using the Newcastle-Ottawa scale
| Reference | Design | Selection | Comparability | Outcome | Total |
|---|---|---|---|---|---|
| Hofhuis et al.(10) | Prospective cohort study | 2 | 0 | 3 | 5 |
| Van den Boogaard et al.(11) | Prospective cohort study | 2 | 0 | 2 | 4 |
| Vaara et al.(12) | Retrospective cohort study | 2 | 0 | 2 | 4 |
| Pavoni et al.(13) | Prospective cohort study | 2 | 0 | 2 | 4 |
| Orwelius et al.(14) | Prospective cohort study | 2 | 0 | 2 | 4 |
| Wolters et al.(15) | Prospective cohort study | 1 | 0 | 1 | 2 |
| Oeyen et al.(16) | Prospective cohort study | 2 | 1 | 2 | 5 |
| Soliman et al.(17) | Prospective cohort study | 1 | 0 | 1 | 2 |
| Hofhuis et al.(18) | Prospective cohort study | 2 | 0 | 2 | 4 |
| Cuthbertson et al.(19) | Prospective cohort study | 2 | 1 | 1 | 4 |
| Battle et al.(20) | Prospective cohort study | 1 | 0 | 1 | 2 |
| Honselmann et al.(21) | Retrospective cohort study | 1 | 1 | 2 | 4 |
| Fan et al.(22 | Prospective cohort study | 1 | 1 | 2 | 4 |
| Heyland et al.(23) | Prospective cohort study | 2 | 0 | 2 | 4 |
| Bagshaw et al.(24) | Prospective cohort study | 1 | 0 | 2 | 3 |
| Feemster et al.(25) | Prospective cohort study | 2 | 0 | 2 | 4 |
| McKinley et al.(26) | Prospective cohort study | 1 | 0 | 2 | 3 |
| McKinley et al.(27) | Prospective cohort study | 2 | 1 | 2 | 5 |
| Zhang K et al.(28) | Prospective case-control study | 2 | 1 | 1 | 4 |
| Das Neves et al.(29) | Prospective cohort study | 1 | 0 | 2 | 3 |
| Contrin et al.(30) | Nested case-control study | 2 | 0 | 2 | 4 |
Strong evidence – 6/9 consistent findings among several high-quality studies; moderately strong evidence – 4-5/9 consistent findings among several low- and/ or high-quality studies; Limited evidence – < 4 low-quality studies; conflicting evidence – inconsistent findings among multiple studies; no evidence – no evidence among studies.