Table 1.
Characteristics of the Derivation and Validation Cohorts
| Derivation Cohort (n = 32,560) |
Validation Cohort (n = 16,281) |
p Value | Standardized Difference* |
|
|---|---|---|---|---|
| Demographics | ||||
| Age, yrs | 65.6 ± 16.1 | 65.6 ± 16.0 | 0.91 | 0.10 |
| Age, yrs, by deciles | 0.54 | |||
| 18 to <50 | 5,269 (16.2%) | 2,594 (15.9%) | ||
| 50 to 59 | 5,476 (16.8%) | 2,832 (17.4%) | ||
| 60 to 69 | 7,137 (21.9%) | 3,556 (21.8%) | ||
| 70 to 79 | 7,562 (23.2%) | 3,793 (23.3%) | ||
| 80 to 89 | 7,116 (21.9%) | 3,506 (21.5%) | ||
| ≥90 | ||||
| Male | 18,996 (58.3%) | 9,500 (58.4%) | 0.99 | 0.02 |
| Race | 0.77 | |||
| White | 22,576 (69.3%) | 11,337 (69.6%) | ||
| Black | 6,678 (20.5%) | 3,288 (20.2%) | ||
| Other | 1,268 (3.9%) | 618 (3.8%) | ||
| Unknown | 2,038 (6.3%) | 1,038 (6.4%) | ||
| Hispanic | 2,254 (6.9%) | 1,060 (6.5%) | 0.09 | 1.65 |
| Pre-existing conditions | ||||
| Respiratory insufficiency | 13,301 (40.9%) | 6,640 (40.8%) | 0.89 | 0.14 |
| Renal insufficiency | 10,850 (33.3%) | 5,358 (32.9%) | 0.36 | 0.88 |
| Arrhythmia | 9,974 (30.6%) | 4,973 (30.5%) | 0.84 | 0.19 |
| Diabetes mellitus | 10,001 (30.7%) | 4,928 (30.3%) | 0.31 | 0.97 |
| Hypotension | 8,413 (25.8%) | 4,308 (26.5%) | 0.14 | 1.42 |
| Heart failure this admission | 5,370 (16.5%) | 2,678 (16.4%) | 0.90 | 0.12 |
| Prior heart failure | 6,278 (19.3%) | 3,094 (19.0%) | 0.46 | 0.71 |
| Myocardial infarction this admission | 5,184 (15.9%) | 2,501 (15.4%) | 0.11 | 1.54 |
| Prior myocardial infarction | 4,791 (14.7%) | 2,319 (14.2%) | 0.16 | 1.34 |
| Metabolic or electrolyte abnormality | 4,765 (14.6%) | 2,280 (14.0%) | 0.06 | 1.80 |
| Septicemia | 5,519 (17.0%) | 2,777 (17.1%) | 0.77 | 0.28 |
| Pneumonia | 4,342 (13.3%) | 2,239 (13.8%) | 0.20 | 1.22 |
| Metastatic or hematologic malignancy | 4,046 (12.4%) | 1,997 (12.3%) | 0.61 | 0.49 |
| Hepatic insufficiency | 2,474 (7.6%) | 1,175 (7.2%) | 0.13 | 1.46 |
| Baseline depression in CNS function | 3,640 (11.2%) | 1,853 (11.4%) | 0.51 | 0.64 |
| Acute CNS non-stroke event | 2,250 (6.9%) | 1,139 (7.0%) | 0.73 | 0.34 |
| Acute stroke | 1,234 (3.8%) | 605 (3.7%) | 0.69 | 0.39 |
| Major trauma | 1,399 (4.3%) | 668 (4.1%) | 0.32 | 0.97 |
| Characteristics of arrest | ||||
| Cardiac arrest rhythm | 0.99 | |||
| Asystole | 10,997 (33.8%) | 5,491 (33.7%) | ||
| Pulseless electrical activity | 15,327 (47.1%) | 7,653 (47.0%) | ||
| Ventricular fibrillation | 3,691 (11.3%) | 1,862 (11.4%) | ||
| Pulseless ventricular tachycardia | 2,545 (7.8%) | 1,275 (7.8%) | ||
| Location | 0.92 | |||
| Intensive care unit | 15,780 (48.5%) | 7,809 (48.0%) | ||
| Monitored unit | 5,034 (15.5%) | 2,539 (15.6%) | ||
| Nonmonitored unit | 5,632 (17.3%) | 2,824 (17.3%) | ||
| Emergency room | 3,307 (10.2%) | 1,687 (10.4%) | ||
| Procedural or surgical area | 2,132 (6.5%) | 1,073 (6.6%) | ||
| Other | 675 (2.1%) | 349 (2.1%) | ||
| Interventions in place | ||||
| Mechanical ventilation | 10,747 (33.0%) | 5,422 (33.3%) | 0.51 | 0.63 |
| Intravenous vasopressor | 9,549 (29.3%) | 4,800 (29.5%) | 0.72 | 0.34 |
| Pulmonary artery catheter | 833 (2.6%) | 378 (2.3%) | 0.11 | 1.53 |
| Dialysis | 1,163 (3.6%) | 598 (3.7%) | 0.57 | 0.54 |
| Intra-aortic balloon pump | 482 (1.5%) | 228 (1.4%) | 0.49 | 0.67 |
Values are mean ± SD or n (%).
*
For binary variables, because of the large sample size, standardized differences of >10 indicate a significant difference between groups.