Risk of bias assessment using the modified Newcastle–Ottawa Scale
| Investigator | Selection bias: is source population representative? | Performance bias | Detection bias | Information bias | Total score* | |||
|---|---|---|---|---|---|---|---|---|
| Is sample size sufficient, is there sufficient power? | Did study adjust for confounders? | Did study use appropriate statistical analysis? | Are there few missing data, was this handled appropriately? | Outcome measurement appropriate? | Objective assessment of outcome of interest? | |||
| Bell et al.48 | 2 | 2 | 3 | 3 | 2 | 2 | 2 | 16 |
| Best et al.30 | 2 | 3 | 2 | 1 | 1 | 2 | 0 | 11 |
| Bleich et al.44 | 1 | 1 | 0 | 1 | 1 | 1 | 3 | 8 |
| Epstein et al.31 | 0 | 1 | 0 | 3 | 2 | 3 | 3 | 12 |
| Joe et al.39 | 3 | 3 | 3 | 3 | 2 | 3 | 3 | 20 |
| Levine et al.32 | 2 | 2 | 2 | 2 | 1 | 3 | 3 | 15 |
| Lions et al.33 | 1 | 2 | 0 | 2 | 1 | 3 | 2 | 11 |
| Nava et al.34 | 0 | 1 | 0 | 2 | 1 | 2 | 3 | 9 |
| Nirenberg et al.35 | 2 | 1 | 0 | 1 | 1 | 3 | 3 | 11 |
| Peirce et al.45 | 1 | 3 | 3 | 3 | 3 | 3 | 3 | 19 |
| Peles et al.40 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 21 |
| Peles et al.41 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 21 |
| Proctor et al.36 | 3 | 3 | 3 | 1 | 1 | 3 | 3 | 17 |
| Saxon et al.46 | 1 | 1 | 0 | 1 | 1 | 2 | 3 | 9 |
| Saxon et al.37 | 2 | 2 | 3 | 2 | 2 | 2 | 3 | 16 |
| Scavone et al.13 | 1 | 1 | 3 | 1 | 2 | 1 | 2 | 11 |
| Schiff et al.42 | 3 | 3 | 2 | 3 | 2 | 3 | 3 | 19 |
| Somers et al.38 | 2 | 1 | 1 | 1 | 2 | 1 | 3 | 11 |
| Strain et al.47 | 2 | 0 | 0 | 1 | 2 | 2 | 1 | 8 |
| Wasserman et al.43 | 2 | 0 | 3 | 3 | 3 | 3 | 3 | 17 |
| Weizman et al.43 | 2 | 2 | 2 | 1 | 1 | 1 | 3 | 12 |
| White et al.17 | 2 | 3 | 0 | 1 | 2 | 2 | 3 | 13 |
| Zielinski et al.14 | 3 | 3 | 3 | 3 | 1 | 2 | 3 | 18 |
↵* 0 = definitely no (high risk of bias), 1 = mostly no (met a little of the criterion), 2 = mostly yes (met most of the criterion), 3 = definitely yes (low risk of bias). Maximum total score 21.