Surgical characteristics of during hours vs after hours groups.
| Characteristic | During Hours Group | After Hours Group | P Value |
| Spinal level, n (%) | 0.5 | ||
| Cervical | 21 (42.9%) | 74 (38.5%) | |
| Thoracic | 14 (28.67%) | 71 (37.0%) | |
| Lumbar | 14 (28.6%) | 47 (24.5%) | |
| Spinal pathology, n (%) | 0.2 | ||
| Degenerative | 19 (38.8%) | 58 (30.2%) | |
| Infection | 7 (14.3%) | 36 (18.8%) | |
| Oncology | 7 (14.3%) | 13 (6.8%) | |
| Trauma | 16 (32.7%) | 85 (44.3%) | |
| Urgency of surgery, n (%) | |||
| Blue immediate | 6 (12.2%) | 8 (4.2%) | 0.03 |
| Blue within 1 h | 11 (22.5%) | 78 (40.6%) | 0.02 |
| Blue within 3 h | 23 (47.0%) | 75 (39.1%) | 0.32 |
| Blue within 6 h | 9 (18.4%) | 31 (16.2%) | 0.71 |
| Length of surgery, min, mean ± SD | 145.3 ± 92.4 | 129.8 ± 83.9 | 0.29 |
| Spinal fusion, n (%) | 28 (57.1%) | 99 (51.9%) | 0.49 |
| C-arm, n (%) | 34 (69.4%) | 138 (71.9%) | 0.73 |
| O-arm, n (%) | 1 (2.0%) | 5 (2.6%) | >0.99 |
| Estimated blood loss, mL, mean ± SD | 303.9 ± 379.5 | 274.4 ± 273.5 | 0.61 |