Risk of bias within included studies
| Study | Selection bias | Performance bias | Detection bias | Attrition bias | Reporting bias | Other bias | Overall bias | ||
| Random sequence generation | Allocation concealment | Participant and personnel blinding | Outcome assessor blinding | Incomplete outcome data | Selective outcome reporting | ||||
| Group research designs | |||||||||
| Level II and III studies | Bar-Haim et al 27 | Low | Low | High | Low | High | Low | High | Low |
| Bleyenheuft et al 25 | Low | Low | High | Unclear | High | Unclear | Unclear | Unclear | |
| Declerck et al 26 | Low | Low | High | Unclear | Unclear | Low | High | Unclear | |
| Grecco et al 28 | Low | Low | High | Low | Unclear | Low | Unclear | Low | |
| Ketelaar et al 33 | Low | Unclear | High | Low | Unclear | Unclear | Unclear | Unclear | |
| Kumban et al 33 | Low | Low | High | Low | High | Low | Unclear | Low | |
| Swe et al 30 | Low | Low | High | Low | Low | Low | Unclear | Low | |
| Capio et al 31 | High | High | High | Unclear | Unclear | Unclear | Unclear | Unclear | |
| Hemayattalab et al 32 | High | Unclear | High | Unclear | Unclear | Unclear | Unclear | Unclear | |
| Hemayattalab and Rostami34 | Unclear | High | High | Unclear | Low | Low | Unclear | Unclear | |
| Löwing et al 35 | High | High | High | High | Low | Low | High | High | |
| IV | Sorsdahl et al 36 | High | High | High | Low | High | Low | Unclear | High |
| Single-subject design | |||||||||
| I | Thorpe and Valvano14 | Low | Unclear | High | High | Low | Low | Unclear | Unclear |