Quality assessment results
| Study | Study design | Description of randomisation | Allocation concealment | Description of withdrawals | Blinding of outcome assessors | Jadad score | PEDro score |
| Anardottir8 | Parallel RCT | + | + | ± | – | 2/5 | 6/10 |
| Coppoolse9 | Parallel RCT | + | – | + | – | 3/5 | 5/10 |
| Mador10 | Parallel RCT | + | + | ± | ± | 2/5 | 8/10 |
| Nasis20 | Parallel RCT | – | – | – | – | 1/5 | 6/10 |
| Puhan11 | Randomised non-inferiority | + | + | + | ± | 3/5 | 8/10 |
| Varga13 | Parallel RCT | – | – | + | – | 2/5 | 6/10 |
| Vogiatzis15 | Parallel RCT | – | – | + | – | 2/5 | 5/10 |
| Vogiatzis16 | Parallel RCT | – | – | – | – | 1/5 | 6/10 |
RCT, randomised controlled trial; +, requirement fulfilled; –, requirement not fulfilled or not reported; ±, requirement partially fulfilled.