Table 1.
Patient characteristics by derivation and validation cohorts
| Variable | Derivation cohort (2006–2007) | Validation cohort (2008) | ||
|---|---|---|---|---|
| Discharges, n (%) | Mortality, n (%) | Discharges, n (%) | Mortality, n (%) | |
| Total | 1 428 824 | 34 147 (2.4) | 770 523 | 18 456 (2.4) |
| Age | ||||
| Age, median (IQR) | 63 (45, 78) | 63 (45, 78) | ||
| Age <65 | 744 160 (52.1) | 7961 (1.1) | 405 566 (52.6) | 4444 (1.1) |
| Age ≥65 | 684 664 (47.9) | 26 186 (3.8) | 364 957 (47.4) | 14 012 (3.8) |
| Gender | ||||
| Men | 579 562 (41.2) | 16 797 (2.9) | 318 966 (41.6) | 9282 (2.9) |
| Women | 849 262 (58.9) | 17 350 (2.0) | 451 557 (58.4) | 9174 (2.0) |
| Race/ethnicity | ||||
| White | 1 177 959 (83.6) | 28 774 (2.4) | 600 305 (78.3) | 14 740 (2.5) |
| Black | 110 565 (7.9) | 2182 (2.0) | 63 908 (8.3) | 1191 (1.9) |
| Other | 140 300 (8.5) | 3191 (2.3) | 106 310 (13.4) | 2525 (2.4) |
| Payer | ||||
| Medicare | 531 347 (37.7) | 19 552 (3.7) | 271 342 (35.4) | 9947 (3.7) |
| Medicaid | 122 650 (8.7) | 1197 (1.0) | 70 193 (9.2) | 715 (1.0) |
| Private or other | 774 827 (53.6) | 13 398 (1.7) | 428 988 (55.5) | 7794 (1.8) |
| Teaching status | ||||
| Teaching | 915 321 (64.1) | 22 004 (2.4) | 496 452 (64.4) | 12 132 (2.4) |
| Non-teaching | 513 503 (35.9) | 12 143 (2.4) | 274 071 (35.6) | 6324 (2.3) |
| Number of beds | ||||
| ≤300 | 751 677 (52.6) | 16 868 (2.2) | 400 131 (51.9) | 8543 (2.1) |
| >300 | 677 147 (47.4) | 17 279 (2.6) | 370 392 (48.1) | 9913 (2.7) |
| Urban/rural status | ||||
| Urban | 1 198 334 (83.9) | 28 768 (2.4) | 655 528 (85.1) | 15 845 (2.4) |
| Rural | 230 490 (16.1) | 5379 (2.3) | 114 995 (14.9) | 2611 (2.3) |
| Medical/surgical discharges | ||||
| Medical | 939 081 (65.7) | 26 621 (2.8) | 514 932 (66.8) | 14 519 (2.8) |
| Surgical | 489 743 (34.3) | 7526 (1.5) | 255 591 (33.2) | 3937 (1.5) |