Cochrane bias rating
| Random sequence generation | Allocation concealment | Blinding of participants and personnel | Blinding of outcome assessment | Incomplete outcome data | Selective reporting | |
|---|---|---|---|---|---|---|
| Altman et al17 | + | + | + | + | − | ? |
| Altman et al18 | + | ? | ? | + | + | + |
| Caborn et al19 | − | − | − | + | − | + |
| Chevalier et al20 | + | + | + | + | + | + |
| Day et al21 | + | ? | + | + | + | ? |
| Decaria et al22 | + | ? | + | + | + | + |
| Housman et al23 | + | + | + | + | + | + |
| Huang et al27 | ? | ? | ? | ? | + | ? |
| Leighton et al24 | + | + | + | + | + | ? |
| Navarro-Sarabia et al25 | + | + | + | + | − | + |
| Strand et al26 | + | + | + | + | ? | ? |