Table 1. Baseline characteristics, comparing patients with IONM and patients without IONM.
| Variable | No IONM (n=18 710) | IONM (n=589) | P value |
| Age (years) | 65.8±11.9 | 64.5±14.0 | 0.010 |
| Sex (female) | 5984 (32.0) | 188 (31.9) | 0.974 |
| Caucasian race | 17 484 (93.5) | 554 (94.1) | 0.555 |
| Body mass index (kg/m2) | 29.9±6.3 | 28.5±6.1 | <0.001 |
| Diabetes mellitus | 7336 (39.2) | 200 (34.0) | 0.010 |
| Chronic dialysis use | 498 (2.7) | 20 (3.4) | 0.278 |
| Chronic lung disease | 4340 (23.2) | 175 (29.7) | <0.001 |
| Peripheral vascular disease | 3083 (16.5) | 160 (27.2) | <0.001 |
| Cerebrovascular disease | 4025 (21.5) | 356 (60.4) | <0.001 |
| Preoperative haematocrit (%) | 38.5±5.7 | 37.0±6.1 | <0.001 |
| Preoperative creatinine (mg/dL) | 1.2±1.0 | 1.2±0.9 | 0.461 |
| Congestive heart failure (≤14 days) | 4951 (26.5) | 182 (30.9) | 0.016 |
| Ejection fraction | 52.2±12.2 | 52.2±12.2 | 0.993 |
| Redo surgery | 1870 (10.0) | 124 (21.1) | <0.001 |
| Surgical status | 0.045 | ||
| Elective | 9292 (49.7) | 283 (48.1) | |
| Urgent | 8755 (46.8) | 295 (50.1) | |
| Emergent/salvage | 663 (3.5) | 11 (1.9) | |
| Cardiopulmonary bypass time (min) | 121±56.6 | 146±73.3 | <0.001 |
| Ischaemic time (min) | 91.1±45.1 | 112±56.3 | <0.001 |
IONMintraoperative neurophysiologic monitoring