Risk of bias assessment
| Selection | Performance | Detection | Attrition | Selective reporting | Other | Score | Correlation | |
| Bullock 201828 | High | Low* | Low | Low | Low | Low | 2 | Ø |
| Chen 201617 | High | Low | Low | Low | Low | High | 4 | Yes |
| Dun 200720 | High | Low | Low | Low | Low | High | 4 | Ø |
| Elliott 198836 | High | Low* | High | High | Low | High | 8 | Yes |
| Escamilla 200214 | High | Low | Low | Low | Low | Low | 2 | Yes |
| Freeston 201549 | High | Low | Low | Low | Low | Low | 2 | Ø |
| Howenstein 201935 | High | High | Unclear | Low | Low | Low | 5 | Yes |
| Jinji 201138 | High | Low | Low | Low | Low | Low | 2 | Yes |
| Kawamura 20176 | High | High | Low | Low | Low | High | 6 | Yes |
| Keller 201530 | High | High | Low | Low | Low | Low | 4 | Ø |
| Lehman 20133 | High | High | Low | Low | Low | Low | 4 | Yes |
| Makhni 201831 | High | High | Low | Low | Low | High | 6 | Yes |
| Matsuo 200125 | High | Low | Low | Low | High | Low | 4 | Yes |
| Murata 200134 | High | Low | Low | Low | High | High | 6 | Yes |
| Nakata 201329 | High | Low | Low | Low | Low | High | 4 | Yes |
| Oyama 201837 | High | Low | Low | High | Low | Low | 4 | Yes |
| Oyama 201316 | High | Low | Low | High | Low | Low | 4 | Yes |
| Oyama 201450 | High | Low | Low | High | Low | Low | 4 | Ø |
| Post 201526 | High | Low | Low | High | Low | Low | 4 | Yes |
| Ramsey 201951 | High | Low | Low | Low | Low | High | 4 | Ø |
| Roach 201452 | High | Low | Low | Low | Low | High | 4 | Yes |
| Robb 201033 | High | Low | Low | Low | High | Low | 4 | Yes |
| Sgroi 201521 | High | High | Low | Low | Low | High | 6 | |
| Solomito 201822 | High | Low | High | Low | Low | High | 6 | Yes |
| Solomito 201524 | High | Low | High | Low | Low | High | 6 | Yes |
| Stodden 200515 | High | Low | Low | Low | Low | High | 4 | Yes |
| Stodden 200123 | High | Low | Low | Low | High | High | 6 | Yes |
| Tocci 201739 | High | Low | Low | Low | Low | High | 4 | Yes |
| Urbin 201327 | High | Low | Low | High | Low | High | 6 | Yes |
| van Trigt 201818 | High | High | High | Low | Low | High | 8 | Yes |
| Wang 199532 | High | Low | High | High | Low | High | 8 | Yes |
| Werner 200819 | High | Low | Low | High | High | Low | 6 | Yes |
| Whiteside 20169 | High | Low | Low | Low | Low | High | 4 | Yes |
| Whiteside 201610 | High | Low | Low | Low | Low | High | 4 | Ø |
Red: high risk of bias; green: low risk of bias; yellow: unclear risk of bias; blue: high risk of bias study (8–12); orange: moderate risk of bias studies (4–7); pink: low risk of bias studies (0–3).