Table 3. Patient Demographics.
| Characteristic | Total population | One-level operated subgroup | Two-level operated subgroup |
|---|---|---|---|
| Total number of patients | 252 | 210 (83.3%) | 42 (16.7%) |
| Gender, n (%): | |||
| Female | 142 (56.3) | 123 (58.6) | 19 (45.2) |
| Male | 110 (43.7) | 87 (41.4) | 23 (54.8) |
| Age, mean ± SD (y) | 53.8 ± 11.8 | 52.8 ± 11.9 | 58.7 ± 9.9 |
| BMI, mean ± SD (kg/m2) | 27.7 ± 4.6 | 27.5 ± 4.5 | 28.4 ± 5.2 |
| Duration of symptoms resulting in planned surgery, mean ± SD (months) | 28.5 ± 38.2 | 27.7 ± 39.5 | 32.5 ± 31.3 |
| Duration of conservative treatment, mean ± SD (months) | 20.7 ± 34.3 | 20.9 ± 35.6 | 19.5 ± 27.4 |
| Pre-existing conditions relevant to study, n (%) | 94 (37.3) | 74 (35.2) | 20 (47.6) |
| Patients with previous lumbar surgeries, n (%) | 47 (18.7) | 39 (18.6) | 8 (19.0) |
| At target level, n (%): | |||
| Microdiscectomy (Open) | 8 (3.2) | 5 (2.4) | 3 (7.1) |
| Microdiscectomy (MIS) | 23 (9.1) | 20 (9.5) | 3 (7.1) |
| Decompression (MIS) | 9 (3.6) | 7 (3.3) | 2 (4.8) |
| Main indication for surgery, n (%): | |||
| Back pain | 98 (38.9) | 85 (40.5) | 13 (31.0) |
| Leg pain | 131 (52.0) | 110 (52.4) | 21 (50.0) |
| Neurogenic claudication | 23 (9.1) | 15 (7.1) | 8 (19.0) |
MIS, minimally invasive surgery.