Table 2.
Summary of reference cohort and testing cohort.
| Overall reference cohort (N=10,000) | Testing cohort (n=150) | |
|---|---|---|
| Demographic features | ||
| Age, median (25th-75th) | 56 (43, 68) | 62 (51, 70) |
| Female sex, n (%) | 4898 (49) | 73 (49) |
| Race, n (%) | ||
| White | 8032 (80) | 125 (83) |
| African-American | 1235 (12) | 19 (13) |
| Hispanic | 338 (3) | 4 (3) |
| Other | 210 (2) | 1 (1) |
| Primary insurance group, n (%) | ||
| Medicare | 3845 (38) | 71 (47) |
| Medicaid | 1294 (13) | 17 (11) |
| Private | 4088 (41) | 57 (38) |
| Uninsured | 773 (8) | 5 (3) |
| Socio-economic features | ||
| Neighborhood characteristics | ||
| Rural area, n (%) | 3156 (32) | 50 (33) |
| Total population, median (25th-75th) | 17176 (10002, 27782) | 16192 (9812, 25971) |
| Median income, median (25th-75th) | 33221 (28400, 40385) | 33293 (28589, 41410) |
| Total proportion of African-Americans (%), mean (SD) | 15 (15) | 16 (16) |
| Total proportion of Hispanic (%), mean (SD) | 6 (6) | 5 (6) |
| Population proportion below poverty (%), mean (SD) | 15 (8) | 14 (8) |
| Distance from residency to hospital (km), median (25th75th) | 54.1 (26.7, 117.7) | 47.8 (21.9, 99.4) |
| Comorbidity features | ||
| Charlson's comorbidity index (CCI), median (25th-75th) | 1 (0, 2) | |
| Cancer, n (%) | 2025 (20) | 27 (18) |
| Diabetes, n (%) | 1620 (16) | 25 (17) |
| Chronic pulmonary disease, n (%) | 1573 (16) | 30 (20) |
| Peripheral vascular disease, n (%) | 1131 (11) | 26 (17) |
| Cerebrovascular disease, n (%) | 823 (8) | 28 (19) |
| Congestive heart failure, n (%) | 781 (8) | 20 (13) |
| Myocardial infarction, n (%) | 650 (7) | 17 (11) |
| Liver disease, n (%) | 503 (5) | 10 (7) |
| Operative features | ||
| Admission | ||
| Weekend admission, n (%) | 142 (14) | 26 (17) |
| Admission source, n (%) | ||
| Emergency room | 2637 (27) | 45 (30) |
| Outpatient setting | 5900 (60) | 76 (51) |
| Transfer | 1334 (14) | 29 (19) |
| Emergent surgery status, n (%) | 4545 (45) | 80 (53) |
| Surgery type, n (%) | ||
| Cardiothoracic surgery | 1284 (13) | 22 (15) |
| Non-cardiac general surgery | 3905 (39) | 54 (36) |
| Neurologic surgery | 1713 (17) | 30 (20) |
| Specialty surgery | 2959 (30) | 41 (27) |
| Other surgery | 139 (1) | 3 (2) |
| Preoperative and admission day laboratory results | ||
| Estimated reference glomerular filtration rate (mL/min/1.73 m2), median (25th-75th) | 91.9 (71.6, 107.8) | 85.8 (56.2, 102.6) |
| Automated urinalysis, urine protein (mg/dL), n (%) | ||
| Missing | 8330 (83) | 124 (83) |
| <30 | 1109 (11) | 15 (10) |
| ≥30 | 561 (6) | 11( 7) |
| Number of complete blood count tests, n (%) | ||
| 0 | 2954 (30) | 34 (23) |
| 1 | 5526 (55) | 88 (59) |
| ≥2 | 1520 (15) | 28 (18) |
| Hemoglobin, g/dL median (25th-75th) | 11.7 (10.2, 13.3) | 11.4 (9.7, 13.0) |
| Hematocrit, median (25th-75th) | 34.4 (30.1, 38.6) | 33.4 (29.1, 37.6) |
| Admission day medications | ||
| Admission day medication groups (top 10 categories), n (%) | ||
| Betablockers | 2333 (23) | 42 (28) |
| Diuretics | 1124 (11) | 19 (13) |
| Statins | 1122 (11) | 23 (15) |
| Aspirin | 671 (7) | 12 (8) |
| Angiotensin-converting-enzyme inhibitors | 979 (10) | 13 (9) |
| Vasopressors and inotropes | 551 (6) | 15 (10) |
| Bicarbonate | 406 (4) | 15 (10) |
| Antiemetics | 5717 (57) | 84 (56) |
| Aminoglycosides | 687 (7) | 5 (3) |
| Corticosteroids | 1218 (12) | 23 (15) |
| Outcomes | ||
| Postoperative complications, n (%) | ||
| Acute kidney injury during hospitalization | 3869 (39) | 82 (55) |
| Intensive care unit admission > 48 hours | 3161 (32) | 74 (49) |
| Mechanical ventilation > 48 hours | 1313 (13) | 55 (37) |
| Wound complications | 1085 (11) | 17 (11) |
| Neurological complications or delirium | 773 (8) | 26 (17) |
| Cardiovascular complications | 724 (7) | 43 (29) |
| Sepsis | 536 (5) | 39 (26) |
| Venous thromboembolism | 287 (3) | 11 (7) |
| Mortality, n (%) | ||
| 30-day mortality | 335 (3) | 24 (16) |
| 3-month mortality | 668 (7) | 41 (27) |
| 6-month mortality | 919 (9) | 46 (31) |
| 12-month mortality | 1261 (13) | 48 (32) |
| 24-month mortality | 1687 (17) | 55 (37) |