Quality appraisal of included studies according to the Downs and Black checklist
| Hypothesis described | Main outcome described | Patient characteristics described | Interventions described | Principal confounders stated | Main findings described | Estimates of outcome variability | Adverse events reported | Characteristics of patients lost to follow-up | Actual probability values | Subject asked to participate representative | Subjects prepared to participate representative | Staff/facilities representative of regular treatment | Results based on data dredging made clear | Different length of follow-up adjusted | Appropriate statistics | Compliance reliable | Outcome valid and reliable | Recruitment over same period | Adjustment for confounders | Loss to follow-up taken into account | |||
| Author | Journal | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 16 | 17 | 18 | 19 | 20 | 22 | 25 | 26 | Total |
| Aga et al 30 | CORR | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 17 |
| Ahldén et al 20 | AJSM | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 15 |
| Andernord et al 11 | AJSM | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 18 |
| Andernord et al 32* | AJSM | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 19 |
| Andernord et al 12† | AJSM | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 18 |
| Björnsson et al 29 | Arthroscopy | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 15 |
| Desai et al 16 | KSSTA | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 17 |
| Eysturoy et al 24 | AJSM | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 14 |
| Fauno et al 17 | OJSM | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 18 |
| Fältström et al 15 | KSSTA | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 18 |
| Gifstad et al 13 | AJSM | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 18 |
| Granan et al 21 | KSSTA | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 19 |
| Granan et al 1 | Acta Orthop | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 11 |
| Kvist et al 10 | Arthroscopy | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 12 |
| Lind et al 8 | KSSTA | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | 9 |
| Lind et al 14 | AJSM | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 13 |
| Magnussen et al 34 | KSSTA | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 12 |
| Magnussen et al 35 | KSSTA | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 12 |
| Maletis et al 2 | JBJS | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 15 |
| Persson et al 19 | AJSM | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 18 |
| Persson et al 26 | AJSM | 1 | 1 | 1 | 1 | 2 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 17 |
| Persson et al 25 | Acta Orthop | 0 | 1 | 0 | 0 | 2 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 13 |
| Prentice et al 7 | BJSM | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 13 |
| Rahr-Wagner et al 31 | Arthroscopy | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 15 |
| Rahr-Wagner et al 5 | Clin Epidemiol | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 0 | 14 |
| Rahr-Wagner et al 22 | AJSM | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 15 |
| Rahr-Wagner et al 27 | Arthroscopy | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 16 |
| Snæbjörnsson et al 23 | AJSM | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 16 |
| Snæbjörnsson et al 33 | KSSTA | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 16 |
| Soreide et al 18 | AJSM | 1 | 1 | 1 | 1 | 2 | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 17 |
| Svantesson et al 28 | KSSTA | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 16 |
*Title: predictors of contralateral ACL reconstruction: a cohort study of 9061 patients with 5-year follow-up.
†Title: patient predictors for early revision surgery after ACL reconstruction: a cohort study of 16 930 patients with 2-year follow-up.
Acta Orthop, Acta Orthopaedica; AJSM, American Journal of Sports Medicine; CORR, Clinical Orthopaedics and Related Research; KSSTA, Knee Surgery, Sport Traumatology, Arthroscopy; OJSM, Orthopaedic Journal of Sports Medicine; JBJS, The Journal of Bone and Joint Surgery; Clin Epidemiol, Journal of Clinical Epidemiology.