Overview risk of bias for the included studies
| Author | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | Total |
| Al Bluwi et al 201126 | U | U | U | N | N | N | Y | U | Y | Y | N | Y | 4 |
| Baldassin et al 200916 | Y | U | U | Y | N | Y | U | U | Y | Y | Y | Y | 7 |
| Caselli et al 199736 | U | U | U | U | U | U | U | U | N | Y | N | N | 1 |
| Dimou et al 200428 | Y | U | U | N | N | Y | U | U | Y | Y | Y | Y | 5 |
| Abd El Salem et al 201131 | U | U | U | N | Y | N | Y | U | Y | Y | Y | Y | 6 |
| Kavros 200522 | U | U | U | N | N | U | Y | U | Y | Y | Y | Y | 5 |
| Kriss 200323 | U | U | U | N | N | N | U | U | Y | Y | Y | N | 3 |
| Landorf et al 200615 | Y | Y | U | Y | U | Y | Y | U | Y | Y | Y | Y | 9 |
| Martin et al 200137 | U | U | Y | N | N | N | U | N | N | Y | U | N | 2 |
| Oliveira et al 201519 | Y | Y | N | Y | N | Y | Y | U | Y | Y | Y | Y | 9 |
| Pfeffer et al 199920 | U | U | Y | N | N | N | Y | U | Y | Y | Y | Y | 6 |
| Rome et al 200429 | U | U | U | N | N | N | Y | U | N | Y | U | Y | 3 |
| Roos et al 200632 | Y | Y | U | N | N | N | U | Y | Y | Y | Y | Y | 7 |
| Sharma and Loudon 201024 | Y | Y | U | N | N | Y | Y | U | Y | Y | N | Y | 7 |
| Turlik et al 199925 | U | U | N | N | N | U | N | U | Y | Y | N | Y | 3 |
| Vicenzino et al 201534 | Y | Y | Y | N | N | Y | U | U | Y | Y | Y | Y | 8 |
| Walther et al 201330 | Y | U | Y | N | N | N | Y | Y | Y | Y | N | Y | 7 |
| Winemiller et al 200327 | Y | Y | N | Y | Y | Y | Y | Y | Y | Y | Y | Y | 11 |
| Wrobel et al 201521 | Y | Y | Y | Y | N | Y | Y | U | Y | Y | N | Y | 9 |
| Yucel et al 201333 | Y | Y | Y | N | N | Y | N | U | Y | Y | N | Y | 7 |
Criteria items: 1. Was the method of randomisation adequate? 2. Was the treatment allocation concealed? 3. Were the groups similar at baseline regarding the most important prognostic indicators? 4. Was the patient blinded to the intervention? 5. Was the care provider blinded to the intervention? 6. Was the outcome assessor blinded to the intervention? 7. Were co-interventions avoided or similar? 8. Was the compliance acceptable in all groups? 9. Was the drop-out rate described and acceptable? 10. Was the timing of the outcome assessment similar in all groups? 11. Were all randomised participants analysed in the group to which they were allocated? 12. Are reports of the study free of suggestion of selective outcome reporting?