Risk of bias assessment
| Study | Potential risk of bias item | Risk of bias | |||||
| 1 | 2 | 3 | 4 | 5 | 6 | ||
| Árnason et al 42 | + | + | + | + | + | + | Low |
| Bengtsson et al 63 | + | – | + | + | – | + | High |
| Bennell et al 65 | + | – | + | + | – | + | High |
| Bennell et al 64 | + | + | – | + | – | + | High |
| Bourne et al 23 | + | – | + | + | + | + | Low |
| Bradley and Portas66 | – | + | + | – | – | + | High |
| Brooks et al 12 | + | + | + | + | – | + | Low |
| Brooks and Kemp67 | + | – | + | + | – | + | High |
| Cameron et al 68 | – | + | + | – | – | + | High |
| Carling et al 69 | – | + | – | + | – | + | High |
| Christensen and Wiseman70 | – | – | – | – | – | – | High |
| Croisier et al 43 | + | + | + | + | – | + | Low |
| Dauty et al 71 | + | + | – | + | – | – | High |
| De Vos et al 44 | + | + | + | + | – | + | Low |
| Duhig et al 28 | + | + | + | + | + | + | Low |
| Elliott et al 72 | – | – | + | + | – | – | High |
| Engebretsen et al 45 | + | + | + | + | + | + | Low |
| Fousekis et al 73 | + | + | – | – | – | + | High |
| Frannetovich-Smith et al 74 | + | + | + | + | – | – | High |
| Freckleton et al 46 | + | + | + | + | – | + | Low |
| Gabbe et al 76 | – | + | – | – | – | + | High |
| Gabbe et al 47 | + | + | + | + | – | + | Low |
| Gabbe et al 75 | – | – | + | + | – | + | High |
| Gibbs et al 77 | + | + | – | + | – | – | High |
| Goossens et al 22 | – | – | – | + | + | + | High |
| Hägglund et al 48 | + | + | + | + | + | + | Low |
| Hägglund et al 49 | + | + | + | + | – | + | Low |
| Henderson et al 50 | + | + | + | + | + | + | Low |
| Iguchi et al 78 | + | + | + | – | – | + | High |
| Koulouris et al 79 | – | + | – | – | – | – | High |
| Lawrence et al 80 | – | + | – | + | – | + | High |
| Lee et al 81 | – | – | + | + | + | + | High |
| Malliaropoulos et al 82 | + | + | – | – | – | – | High |
| Malliaropoulos et al 51 | + | + | + | + | + | + | Low |
| Opar et al 83 | + | + | + | – | – | + | High |
| Opar et al 25 | + | + | + | + | + | + | Low |
| Orchard et al 84 | + | – | + | + | – | + | High |
| Orchard et al 52 | + | – | + | + | + | + | Low |
| Orchard et al 29 | – | – | + | + | – | + | High |
| Orchard et al 30 | – | – | + | + | + | + | High |
| Orchard et al 85 | – | + | + | + | – | + | High |
| Pollock et al 86 | – | + | + | + | + | – | High |
| Reurink et al 87 | – | + | + | – | – | + | High |
| Roe et al 88 | – | – | + | + | – | + | High |
| Rolls and George89 | – | + | + | – | – | + | High |
| Ruddy et al 27 | + | + | + | + | + | + | Low |
| Schuermans et al 21 | + | – | – | + | – | – | High |
| Schuermans et al 90 | + | – | – | + | + | + | High |
| Schuermans et al 91 | + | – | + | – | – | + | High |
| Schuermans et al 92 | + | – | + | – | – | + | High |
| Sugiura et al 53 | + | + | – | + | + | + | Low |
| Timmins et al 24 | + | + | + | + | + | + | Low |
| van der Made et al 93 | – | – | + | + | + | + | High |
| van der Made et al 54 | + | + | + | + | + | + | Low |
| van Doormaal et al 19 | + | – | + | – | + | + | High |
| van Dyk et al 20 | + | + | + | + | + | + | Low |
| van Dyk et al 55 | + | – | + | + | + | + | Low |
| van Dyk et al 56 | + | + | + | + | + | + | Low |
| van Dyk et al 57 | + | + | + | + | + | + | Low |
| Venturelli et al 94 | + | + | + | – | – | + | High |
| Verrall et al 58 | + | + | + | + | – | + | Low |
| Verrall et al 95 | + | + | + | – | – | + | High |
| Warren et al 59 | + | + | + | + | – | + | Low |
| Watsford et al 60 | + | – | + | + | + | + | Low |
| Witvrouw et al 96 | – | – | – | – | – | – | High |
| Woods et al 97 | + | – | – | – | – | – | High |
| Yamada and Matsumoto98 | – | + | – | – | – | – | High |
| Yamamoto et al 99 | – | – | – | – | – | – | High |
| Yeung et al 61 | + | + | + | + | – | + | Low |
| Zvijac et al 62 | + | + | + | + | – | + | Low |
1, study participation, 2, study attrition, 3, prognostic factor measurement, 4, outcome measurement, 5, study confounding variables, 6, statistical analysis and reporting.