Table 1.
Characteristics of the Derivation and Validation Cohorts
| Derivation Cohort (n=55 601) | Validation Cohort (n=27 128) | Standardized Difference %* | |
|---|---|---|---|
| Demographics | |||
| Age (y), mean±SD | 65.2±15.6 | 65.3±15.5 | 0.5 |
| Age, y, by deciles | 1.6 | ||
| 18 to <50 | 8303 (14.9%) | 3997 (14.7%) | |
| 50–59 | 9434 (17.0%) | 4726 (17.4%) | |
| 60–69 | 14 276 (25.7%) | 6830 (25.2%) | |
| 70–79 | 13 299 (23.9%) | 6526 (24.1%) | |
| 80–89 | 10 289 (18.5%) | 5049 (18.6%) | |
| Male sex | 32 517 (58.5%) | 15 891 (58.6%) | 0.2 |
| Race | 1.6 | ||
| White | 37 658 (67.7%) | 18 382 (67.8%) | |
| Black | 12 658 (22.8%) | 6282 (23.2%) | |
| Other | 1370 (2.5%) | 626 (2.3%) | |
| Unknown | 3915 (7.0%) | 1838 (6.8%) | |
| Characteristics of arrest | |||
| Cardiac arrest rhythm | 1.9 | ||
| Asystole | 14 511 (26.1%) | 7193 (26.5%) | |
| Pulseless electrical activity | 31 575 (56.8%) | 15 323 (56.5%) | |
| Ventricular fibrillation | 5273 (9.5%) | 2645 (9.8%) | |
| Pulseless ventricular tachycardia | 4242 (7.6%) | 1967 (7.3%) | |
| Location of cardiac arrest | 1.4 | ||
| Intensive care unit | 27 060 (48.7%) | 13 320 (49.1%) | |
| Monitored unit | 8396 (15.1%) | 4054 (14.9%) | |
| Nonmonitored unit | 8221 (14.8%) | 4066 (15.0%) | |
| Emergency room | 6600 (11.9%) | 3151 (11.6%) | |
| Procedural or surgical area | 4340 (7.8%) | 2065 (7.6%) | |
| Other | 984 (1.8%) | 472 (1.7%) | |
| Pre‐existing conditions | |||
| Respiratory insufficiency | 25 911 (46.6%) | 12 795 (47.2%) | 1.1 |
| Renal insufficiency | 20 107 (36.2%) | 9960 (36.7%) | 1.1 |
| Diabetes mellitus | 18 985 (34.1%) | 9345 (34.4%) | 0.6 |
| Hypotension | 14 622 (26.3%) | 7212 (26.6%) | 0.7 |
| Heart failure this admission | 8241 (14.8%) | 3981 (14.7%) | 0.4 |
| Prior heart failure | 12 419 (22.3%) | 6052 (22.3%) | 0.1 |
| Myocardial infarction this admission | 7992 (14.4%) | 3853 (14.2%) | 0.5 |
| Prior myocardial infarction | 7525 (13.5%) | 3711 (13.7%) | 0.4 |
| Metabolic or electrolyte abnormality | 12 990 (23.4%) | 6337 (23.4%) | 0.0 |
| Septicemia | 10 298 (18.5%) | 5252 (19.4%) | 2.1 |
| Pneumonia | 7820 (14.1%) | 3918 (14.4%) | 1.1 |
| Metastatic or hematologic malignancy | 6009 (10.8%) | 2885 (10.6%) | 0.6 |
| Hepatic insufficiency | 4504 (8.1%) | 2273 (8.4%) | 1.0 |
| Baseline depression in CNS function | 4085 (7.3%) | 1954 (7.2%) | 0.6 |
| Acute CNS nonstroke event | 4004 (7.2%) | 1949 (7.2%) | 0.1 |
| Acute stroke | 2249 (4.0%) | 1066 (3.9%) | 0.6 |
| Major trauma | 2660 (4.8%) | 1316 (4.9%) | 0.3 |
| Interventions in place | |||
| Mechanical ventilation | 13 494 (24.3%) | 6601 (24.3%) | 0.1 |
| Continuous intravenous vasopressor | 13 301 (23.9%) | 6548 (24.1%) | 0.5 |
| Dialysis | 1505 (2.7%) | 767 (2.8%) | 0.7 |
CNS indicates central nervous system.
*
A standardized difference of >10% indicates a significant difference between groups.