Table 1. Baseline Clinical Characteristics and Operative Information of Derivation and Validation Cohorts.
| Characteristic | No. (%) | |
|---|---|---|
| Derivation (n = 58 526) | Validation (n = 4734) | |
| Age, y | ||
| Median (IQR) | 66 (56-74) | 67 (60-74) |
| Men | 39 173 (67) | 3361 (71) |
| Women | 19 353 (33) | 1373 (29) |
| Racea | n = 56 368 | n = 4589 |
| Asian | 679 (1) | 60 (1) |
| Black | 2926 (6) | 474 (10) |
| Multiracial | 1260 (2) | 78 (2) |
| White | 51 503 (91) | 3977 (87) |
| Weight, median (IQR), kg | 82 (71-95) | 85 (74-99) |
| Comorbid diseaseb | ||
| Hypertension | 39 156 (67) | 3124 (66) |
| Diabetes | 13 726 (23) | 1373 (29) |
| Congestive heart failure | 13 671 (23) | 329 (7) |
| Coronary artery disease | 12 441 (21) | 1848 (39) |
| Pulmonary disease | 7561(13) | 565 (12) |
| Chronic kidney disease | 1776 (3) | 236 (5) |
| Preoperative laboratories, median (IQR)c | ||
| Time from blood draw to operation, d | 2 (0-5) | 2 (0-7) |
| Serum albumin, g/dL | 4.2 (3.8-4.4) | 4.2 (3.8-4.4) |
| Serum bicarbonate, mmol/L | 26 (24-28) | 26 (24-27) |
| Blood urea nitrogen, mg/dL | 18 (15-23) | 17 (14-22) |
| Serum creatinine, mg/dL | 1.0 (0.84-1.18) | 0.97 (0.82-1.15) |
| Serum potassium, mmol/L | 4.1 (3.9-4.4) | 4.2 (4-4.5) |
| Serum sodium, mmol/L | 140 (138-142) | 139 (138-141) |
| Operative procedured | ||
| Valve surgery alone | 23 314 (40) | 1041 (22) |
| CABG alone | 13 648 (23) | 2980 (63) |
| Aorta surgery | 11 521 (20) | 390 (8) |
| CABG and valve surgery | 10 043 (17) | 323 (7) |
Abbreviation: CABG, coronary artery bypass graft.
Race information was obtained based on self-identification using fixed categories retrieved from medical records. A total of 226 patients in the derivation cohort and 65 in the validation cohort declined to provide a response.
Comorbid disease was assessed using the International Classification of Diseases, Ninth Revision and International Classification of Diseases, Tenth Revision codes.
Normal laboratory ranges for preoperative laboratory were as follows: serum albumin, 3.9-4.9 mg/dL; serum bicarbonate, 22-30 mmol/L; blood urea nitrogen, 7-21 mg/dL; serum creatinine, 0.58-0.96 mg/dL for women and 0.73-1.22 mg/dL for men; serum potassium, 3.7-5.1 mmol/L; and serum sodium, 136-144 mmol/L.
Aorta surgery included root, ascending, and thoracoabdominal aortic surgery. Valve surgery included aortic, mitral, pulmonary, and tricuspid valve surgery; 96% of operations were performed using cardiopulmonary bypass.