Baseline characteristics of included studies.
| Authors | Design | Sample, n | Age, y, mean ± SD | Female, % | BMI | Baseline ODI, mean ± SD | Last Follow-up, mo | NOS |
| Austevoll 20202 | Multicenter prospective cohort (PSM) | 570 | 64.7 ± 9.5 | 72.5 | 26.9 ± 4.5 | 41.1 ± 14.9 | 12 | 8 |
| Chan 20194 | Multicenter prospective cohort | 426 | 62.5 ± 11.5 | 59.2 | 30.5 ± 6.5 | 47.7 ± 16.9 | 12 | 7 |
| Försth 201316 | Multicenter prospective cohort | 1306 | 69.4 ± 29.6 | 65.7 | NR | 44.4 ± 15.8 | 25 | 6 |
| Försth 20166 | Multicenter RCT | 135 | 67.5 ± 7.0 | 79.2 | NR | 41.0 ± 13.5 | 24 | RoBa |
| Ghogawala 20047 | Multicenter prospective cohort | 34 | 68.8 ± 8.0 | 68.0 | NR | 41.2 | 12 | 6 |
| Ghogawala 20168 | Multicenter RCT | 66 | 66.6 ± 7.6 | 80.3 | NR | 37.5 ± 15.5 | 48 (24 for analysis) | RoBa |
| Inose 20183 | Multicenter RCT | 60 | 62.3 ± 7.7 | 53.3 | NR | NR | 60 | RoBa |
| Kim 20189 | Prospective cohort | 129 | 66.1 ± 8.9 | 77.5 | 21.4 ± 5.2 | NR | 24 | 7 |
| Kleinstueck 201110 | Prospective cohort | 213 | 68.9 ± 9.3 | 72.7 | NR | NR | 12 | 7 |
| Matsudaira 200511 | Retrospective cohort | 39 | 67.5 ± 6.9 | 59.5 | NR | NR | 24 | 7 |
| Park 201212 | Retrospective cohort | 45 | 64.3 ± 19.6 | 82.2 | 25.8 ± 4.7 | 26.9 ± 5.6 | 63 | 7 |
| Sigmundsson 201513 | Retrospective cohort | 839 | 70.3 ± 9.5 | 76.9 | NR | 44.9 ± 14.8 | 36 | 6 |
| Ulrich 201715 | Retrospective cohort | 131 | 72.3 ± 8.4 | 58.0 | NR | NR | 36 | 7 |
aSee Figure 5A.
BMI, body mass index; NOS, Newcastle-Ottawa Scale; NR, not reported; ODI, Oswestry Disability Index; PSM, propensity-score matching; RoB, Cochrane risk of bias assessment tool.