Table 2.
Risk of bias in included studies. With the Quality in Prognostic Studies tool studies were assessed on the overall risk of bias within each of the six domains and rated as low, moderate or high risk of bias
| Study author year | Design | Study participation | Study attrition | Prognostic factor measurement | Outcome measurement | Study confounding | Statistical analysis and presentation |
| Blauuw et al 201519 | Prospective cohort | Low | Moderate | Low | Low | Moderate | Low |
| Brattberg 199320 | Prospective cohort | Moderate | Moderate | Low | Low | Moderate | High |
| Brattberg 200421 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| El-Metwally et al 200422 | Prospective cohort | Low | Low | Low | Low | Low | Low |
| El-Metwally et al 200549 | Prospective cohort | Low | Low | Low | Low | Low | Low |
| Flatø et al 199723 | Prospective cohort | Low | Low | Low | Low | Low | Low |
| Holley et al 201724 | Prospective cohort | Low | Low | Low | Low | Low | Low |
| Jones and Macfarlane 200925 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Jussila et al 201426 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Laimi et al 200727 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Lunde et al 201528 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Mikkelsson et al 199729 | Prospective cohort | Low | Low | Low | Low | Moderate | Moderate |
| Mikkelsson et al 199830 | Prospective cohort | Low | Low | Low | Low | Low | Moderate |
| Mikkelsson et al 199931 | Prospective cohort | Low | Low | Low | Low | Low | Low |
| Mikkonen et al 200832 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Mikkonen et al 201233 | Prospective cohort | Moderate | Low | Low | Low | Low | Low |
| Mikkonen et al 201334 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Paananen et al 201035 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Rathleff et al 20139 | Prospective cohort and nested case–control | Moderate | Low | Low | Low | Low | Low |
| Rathleff et al 201636* | Prospective cohort | Low | Low | Low | Low | Low | Low |
| Rathleff et al 201637 | Prospective cohort | Low | Low | Low | Low | Low | Low |
| Sjölie and Ljunggren 200138 | Prospective cohort study with a cross sectional part | Low | Low | Low | Low | Low | Low |
| Sperotto et al 201539 | Prospective cohort | Low | Moderate | Low | Low | High | Moderate |
| Stanford et al 200817 | Prospective cohort | Low | Moderate | Low | Low | Low | Low |
| Ståhl et al 200840 | Prospective cohort | Low | Moderate | Low | Low | Moderate | Low |
| Uziel et al 201041 | Prospective cohort | Moderate | Low | Low | Low | High | Moderate |
*‘Is knee pain during adolescence a self-limiting condition?’