Table 2. Patient demographics and baseline characteristics .
| Total number of patients | 252 |
| Gender (% females) | 56.3 |
| Mean (±SD) age (y) | 53.8 (±11.8) |
| Mean (±SD) BMI (kg/m2) | 27.7 (±4.6) |
| Mean (±SD) duration of symptoms resulting in planned surgery (mo) | 28.5 (±38.2) |
| Mean (±SD) duration of conservative treatment (mo) | 20.7 (±34.3) |
| Pre-existing conditions relevant to study (%) | 37.3% |
| Previous lumbar surgeries (%) | 15.1% |
| At target level: | |
| Microdiscectomy open surgery | 3.2% |
| Microdiscectomy minimally invasive surgery | 9.1% |
| Decompression (minimally invasive surgery) | 3.6% |