Table 1. Baseline Characteristics and Candidate Variables for Risk-Prediction Model.
| Entire Cohort, N = 32,922 | Derivation Cohort, N = 16,492 | |||
|---|---|---|---|---|
|
| ||||
| No Readmission, N = 14,312 | Readmission, N = 2,180 | P Value | ||
| Demographic characteristics | ||||
| Age, y, mean (SD) | 62 (17.3) | 61 (17.4) | 64 (17.0) | ≤0.001 |
| Female, n (%) | 17,715 (53.8) | 7,694 (53.8) | 1,163 (53.3) | 0.72 |
| Race/ethnicity | ≤0.001 | |||
| white | 21,359 (64.9) | 9,239 (65.2) | 1,361 (62.4) | |
| Black | 5,964 (18.1) | 2,520 (17.6) | 434 (19.9) | |
| Hispanic | 4,452 (13.5) | 1,931 (13.5) | 338 (15.5) | |
| Other | 1,147 (3.5) | 532 (3.7) | 47 (2.2) | |
| Marital status, n (%) | ≤0.001 | |||
| Single | 8,076 (24.5) | 3,516 (24.6) | 514 (23.6) | |
| Married | 13,394 (40.7) | 5,950 (41.6) | 812 (37.3) | |
| Separated/divorced | 3,468 (10.5) | 1,460 (10.2) | 251 (11.5) | |
| Widowed | 4,487 (13.7) | 1,868 (13.1) | 388 (17.8) | |
| Other | 3,497 (10.6) | 1,518 (10.6) | 215 (9.9) | |
| Primary payer, n (%) | ≤0.001 | |||
| Private | 13,090 (39.8) | 5,855 (40.9) | 726 (33.3) | |
| Medicare | 13,015 (39.5) | 5,597 (39.1) | 987 (45.3) | |
| Medicaid | 2,204 (6.7) | 852 (5.9) | 242 (11.1) | |
| Charity, self-pay, or other | 4,613 (14.0) | 2,008 (14.0) | 225 (10.3) | |
| High-poverty neighborhood, n (%)* | 7,468 (22.7) | 3,208 (22.4) | 548 (25.1) | ≤0.001 |
| Utilization history | ||||
| ≥1 ED visits in past year, n (%)† | 9,299 (28.2) | 3,793 (26.5) | 823 (37.8) | ≤0.001 |
| ≥1 hospitalizations in past year, n (%)‡ | 10,189 (30.9) | 4,074 (28.5) | 1,012 (46.4) | ≤0.001 |
| Clinical factors from first day of hospitalization | ||||
| Nonelective admission, n (%)□ | 27,818 (84.5) | 11,960 (83.6) | 1,960 (89.9) | ≤0.001 |
| Charlson Comorbidity Index, median (IQR)‖ | 0 (0–1) | 0 (0–0) | 0 (0–3) | ≤0.001 |
| Laboratory abnormalities within 24 hours of admission | ||||
| Albumin <2 g/dL | 355 (1.1) | 119 (0.8) | 46 (2.1) | ≤0.001 |
| Albumin 2–3 g/dL | 4,732 (14.4) | 1,956 (13.7) | 458 (21.0) | ≤0.001 |
| Aspartate aminotransferase >40 U/L | 4,610 (14.0) | 1,922 (13.4) | 383 (17.6) | ≤0.001 |
| Creatine phosphokinase <60 μg/L | 3,728 (11.3) | 1,536 (10.7) | 330 (15.1) | ≤0.001 |
| Mean corpuscular volume >100 fL/red cell | 1,346 (4.1) | 537 (3.8) | 134 (6.2) | ≤0.001 |
| Platelets <90 × 103/μL | 912 (2.8) | 357 (2.5) | 116 (5.3) | ≤0.001 |
| Platelets >350 × 103/μL | 3,332 (10.1) | 1,433 (10.0) | 283 (13.0) | ≤0.001 |
| Prothrombin time >35 seconds | 248 (0.8) | 90 (0.6) | 35 (1.6) | ≤0.001 |
| Clinical factors from remainder of hospital stay | ||||
| Length of stay, d, median (IQR) | 4 (2–6) | 4 (2–6) | 5 (3–8) | ≤0.001 |
| ICU transfer after first 24 hours, n (%) | 988 (3.0) | 408 (2.9) | 94 (4.3) | ≤0.001 |
| Hospital complications, n (%)Ñ | ||||
| Clostridium difficile infection | 119 (0.4) | 44 (0.3) | 24 (1.1) | ≤0.001 |
| Pressure ulcer | 358 (1.1) | 126 (0.9) | 46 (2.1) | ≤0.001 |
| Venous thromboembolism | 301 (0.9) | 112 (0.8) | 34 (1.6) | ≤0.001 |
| Respiratory failure | 1,048 (3.2) | 463 (3.2) | 112 (5.1) | ≤0.001 |
| Central line-associated bloodstream infection | 22 (0.07) | 6 (0.04) | 5 (0.23) | 0.005 |
| Catheter-associated urinary tract infection | 47 (0.14) | 20 (0.14) | 6 (0.28) | 0.15 |
| Acute myocardial infarction | 293 (0.9) | 110 (0.8) | 32 (1.5) | ≤0.001 |
| Pneumonia | 1,754 (5.3) | 719 (5.0) | 154 (7.1) | ≤0.001 |
| Sepsis | 853 (2.6) | 368 (2.6) | 73 (3.4) | 0.04 |
| Blood transfusion during hospitalization, n (%) | 4,511 (13.7) | 1,837 (12.8) | 425 (19.5) | ≤0.001 |
| Laboratory abnormalities at discharge# | ||||
| Blood urea nitrogen >20 mg/dL, n (%) | 10,014 (30.4) | 4,077 (28.5) | 929 (42.6) | ≤0.001 |
| Sodium <135 mEq/L, n (%) | 4,583 (13.9) | 1,850 (12.9) | 440 (20.2) | ≤0.001 |
| Hematocrit ≤27 | 3,104 (9.4) | 1,231 (8.6) | 287 (13.2) | ≤0.001 |
| ≥1 vital sign instability at discharge, n (%)# | 6,192 (18.8) | 2,624 (18.3) | 525 (24.1) | ≤0.001 |
| Discharge location, n (%) | ≤0.001 | |||
| Home | 23,339 (70.9) | 10,282 (71.8) | 1,383 (63.4) | |
| Home health | 3,185 (9.7) | 1,356 (9.5) | 234 (10.7) | |
| Post–acute care** | 5,990 (18.2) | 2,496 (17.4) | 549 (25.2) | |
| Hospice | 408 (1.2) | 178 (1.2) | 14 (0.6) | |
NOTE: Abbreviations: ED, emergency department; ICU, intensive care unit; IQR, interquartile range; SD, standard deviation.
≥20% poverty in zip code as per “high poverty” area US Census designation.
Prior ED visit at site of index hospitalization within the past year.
Prior hospitalization at any of 75 acute care hospitals in the North Texas region within the past year.
Nonelective admission defined as hospitalization categorized as medical emergency, urgent, or trauma.
Calculated from diagnoses available within 1 year prior to index hospitalization.
Conditions were considered complications if they were not listed as a principle diagnosis for hospitalization or as a previous diagnosis in the prior year.
On day of discharge or last known observation before discharge. Instabilities were defined as temperature ≥37.8°C, heart rate >100 beats/minute, respiratory rate >24 breaths/minute, systolic blood pressure ≤90 mm Hg, or oxygen saturation <90%.
Discharges to nursing home, skilled nursing facility, or long-term acute care hospital.