Table 1.
Characteristics of the Case and Control Cohorts
| Factors | Control (January 2018‒February 2020) (n=5,209) | Case (March 2020‒April 2021) (n=589) | Overall (N=5,798) | p-value |
|---|---|---|---|---|
| Age, years | ||||
| Mean (SD) | 58.6 (14.6) | 48.2 (17.8) | 57.5 (15.3) | <0.001 |
| Median (min, max) | 60.4 (18.0, 101) | 48.3 (14.1, 89.2) | 59.6 (14.1, 101) | |
| Race, n (%) | ||||
| White | 3,627 (69.6) | 292 (49.6) | 3,919 (67.6) | <0.001 |
| Black | 1,478 (28.4) | 247 (41.9) | 1,725 (29.8) | |
| Asian | 52 (1.0) | 12 (2.0) | 64 (1.1) | |
| Other | 52 (1.0) | 38 (6.5) | 90 (1.6) | |
| Sex, n (%) | ||||
| Female | 3,165 (60.8) | 361 (61.3) | 3,526 (60.8) | 0.837 |
| Male | 2,044 (39.2) | 228 (38.7) | 2,272 (39.2) | |
| BMI | ||||
| Mean (SD) | 30.3 (7.74) | 31.2 (8.89) | 30.4 (7.87) | 0.0184 |
| Median (min, max) | 29.2 (13.7, 90.9) | 29.4 (14.7, 69.8) | 29.2 (13.7, 90.9) | |
| Missing, n (%) | 19 (0.4) | 0 (0) | 19 (0.3) | |
| History of smoking, n (%) | ||||
| None | 4,215 (80.9) | 317 (53.8) | 4,532 (78.2) | <0.001 |
| Within the past year | 994 (19.1) | 272 (46.2) | 1,266 (21.8) | |
| ASA, n (%) | ||||
| 1 | 52 (1.0) | 16 (2.7) | 68 (1.2) | <0.001 |
| 2 | 925 (17.8) | 127 (21.6) | 1,052 (18.1) | |
| 3 | 3,883 (74.5) | 368 (62.5) | 4,251 (73.3) | |
| 4 | 343 (6.6) | 74 (12.6) | 417 (7.2) | |
| 5 | 6 (0.1) | 2 (0.3) | 8 (0.1) | |
| Missing | 0 (0) | 2 (0.3) | 2 (0.0) | |
| Case type, n (%) | ||||
| Emergent | 4,296 (82.5) | 328 (55.7) | 4,624 (79.8) | <0.001 |
| Elective | 913 (17.5) | 261 (44.3) | 1,174 (20.2) | |
| Wound classification, n (%) | ||||
| Clean | 2,290 (44.0) | 286 (48.6) | 2,576 (44.4) | <0.001 |
| Clean/contaminated | 2,450 (47.0) | 197 (33.4) | 2,647 (45.7) | |
| Contaminated | 191 (3.7) | 45 (7.6) | 236 (4.1) | |
| Dirty/infected | 278 (5.3) | 61 (10.4) | 339 (5.8) | |
| Case duration, hours | ||||
| Mean (SD) | 2.61 (1.65) | 1.62 (1.32) | 2.51 (1.65) | <0.001 |
| Median (min, max) | 2.18 (0.200, 13.8) | 1.30 (0.0333, 8.90) | 2.08 (0.0333, 13.8) | |
| Specialty, n (%) | ||||
| General surgery | 2,429 (46.6) | 136 (23.1) | 2,565 (44.2) | <0.001 |
| Orthopedics | 910 (17.5) | 179 (30.4) | 1,089 (18.8) | |
| Gynecology | 657 (12.6) | 120 (20.4) | 777 (13.4) | |
| Neurosurgery | 447 (8.6) | 42 (7.1) | 489 (8.4) | |
| Vascular | 363 (7.0) | 61 (10.4) | 424 (7.3) | |
| Thoracic | 386 (7.4) | 11 (1.9) | 397 (6.8) | |
| Plastics | 17 (0.3) | 40 (6.8) | 57 (1.0) | |
| Mortality, n (%) | ||||
| Survived | 5,155 (99.0) | 563 (95.6) | 5,718 (98.6) | <0.001 |
| Mortality | 54 (1.0) | 26 (4.4) | 80 (1.4) |
Note: Boldface indicates statistical significance (p<0.05).
ASA, American Society of Anesthesiologists Physical Status Classification Score; max, maximum; min, minimum.