TABLE 1.
Study cohort characteristics.
| Total | Spatial method | Temporal method | |||
|---|---|---|---|---|---|
| Derivation cohort | Validation cohort | Derivation cohort | Validation cohort | ||
| Total visits | 8032 | 5087 | 2945 | 5352 | 2680 |
| Age, N (%) | |||||
| 18–44 years | 3379 (42.1) | 2338 (46.0) | 1041 (35.3) | 1910 (35.7) | 1469 (54.8) |
| 45–64 years | 2311 (28.8) | 1441 (28.3) | 870 (29.5) | 1594 (29.8) | 717 (26.8) |
| 65–74 years | 978 (12.2) | 554 (10.9) | 424 (14.4) | 742 (13.9) | 236 (8.8) |
| >74 years | 1364 (17.0) | 754 (14.8) | 610 (20.7) | 1106 (20.7) | 258 (9.6) |
| Gender, N (%) | |||||
| Female | 4614 (57.4) | 2949 (58.0) | 1665 (56.5) | 3076 (57.5) | 1538 (57.4) |
| Race/ethnicity, N (%) | |||||
| Black non‐Latino | 3096 (38.5) | 2347 (46.1) | 749 (25.4) | 1950 (36.4) | 1146 (42.8) |
| White non‐Latino | 3154 (39.3) | 1726 (33.9) | 1428 (48.5) | 2306 (43.1) | 848 (31.6) |
| Latino | 910 (11.3) | 441 (8.7) | 469 (15.9) | 502 (9.4) | 408 (15.2) |
| Other | 872 (10.9) | 573 (11.3) | 299 (10.2) | 594 (11.1) | 278 (10.4) |
| Chief complaint, N (%) | |||||
| Upper respiratory infection symptoms | 2134 (26.6) | 1588 (31.2) | 546 (18.5) | 1270 (23.7) | 864 (32.2) |
| Fever | 1873 (23.3) | 1046 (20.6) | 827 (28.1) | 1288 (24.1) | 585 (21.8) |
| Lower respiratory infection symptoms | 1472 (18.3) | 828 (16.3) | 644 (21.9) | 1013 (18.9) | 459 (17.1) |
| Shortness of breath | 1332 (16.6) | 770 (15.1) | 562 (19.1) | 984 (18.4) | 348 (13.0) |
| Chest pain | 485 (6.0) | 311 (6.1) | 174 (5.9) | 332 (6.2) | 153 (5.7) |
| Comorbidities, N (%) | |||||
| Atrial fibrillation | 336 (4.2) | 203 (4.0) | 133 (4.5) | 264 (4.9) | 72 (2.7) |
| Coronary artery disease | 395 (4.9) | 219 (4.3) | 176 (6.0) | 305 (5.7) | 90 (3.4) |
| Cancer | 552 (6.9) | 366 (7.2) | 186 (6.3) | 418 (7.8) | 134 (5.0) |
| Cerebrovascular disease | 292 (3.6) | 219 (4.3) | 73 (2.5) | 216 (4.0) | 76 (2.8) |
| Diabetes | 653 (8.1) | 405 (8.0) | 248 (8.4) | 474 (8.9) | 179 (6.7) |
| Heart failure | 410 (5.1) | 242 (4.8) | 168 (5.7) | 318 (5.9) | 92 (3.4) |
| Hypertension | 1146 (14.3) | 688 (13.5) | 458 (15.6) | 835 (15.6) | 311 (11.6) |
| Immunosuppression | 550 (6.8) | 404 (7.9) | 146 (5.0) | 396 (7.4) | 154 (5.7) |
| Kidney disease | 554 (6.9) | 348 (6.8) | 206 (7.0) | 418 (7.8) | 136 (5.1) |
| Liver disease | 812 (10.1) | 493 (9.7) | 319 (10.8) | 570 (10.7) | 242 (9.0) |
| Pregnancy | 216 (2.7) | 149 (2.9) | 67 (2.3) | 107 (2.0) | 109 (4.1) |
| Prior respiratory failure | 220 (2.7) | 146 (2.9) | 74 (2.5) | 160 (3.0) | 60 (2.2) |
| Smoker | 318 (4.0) | 168 (3.3) | 150 (5.1) | 232 (4.3) | 86 (3.2) |
| Vital signs, mean (95% CI) | |||||
| Temperature | 99.2 (97.2–102.7) | 99.2 (97.2–102.7) | 99.2 (97.3–102.7) | 99.2 (97.3–102.7) | 99.2 (97.0–102.7) |
| Heart rate | 90.6 (60.0–125.0) | 91.2 (60.0–125.0) | 89.7 (59.0–126.0) | 90.1 (59.0–125.0) | 91.7 (61.0–126.0) |
| Respiratory rate | 18.6 (14.0–28.0) | 18.2 (14.0–26.0) | 19.3 (14.0–32.0) | 18.7 (14.0–29.0) | 18.3 (14.0–27.0) |
| Oxygen saturation | 97.0 (92.0–100.0) | 97.2 (92.0–100.0) | 96.7 (91.0–100.0) | 96.9 (91.0–100.0) | 97.3 (92.0–100.0) |
| Systolic blood pressure | 128.1 (95.0–177.0) | 127.1 (96.0–173.0) | 129.8 (94.0–180.0) | 128.8 (95.0–177.0) | 126.7 (94.5–175.0) |
| Labs, N tested, mean (95% CI) | |||||
| Absolute lymphocyte count, K/cu mm | 596, 2.2 (0.2–5.0) | 365, 1.7 (0.2–4.7) | 231, 3.0 (0.2–8.2) | 439, 2.4 (0.2–4.8) | 157, 1.7 (0.2–5.1) |
| Alanine aminotransferase, U/L | 5747, 31.6 (8.0–105.0) | 3385, 31.4 (8.0–101.0) | 2362, 31.8 (9.0–112.0) | 4054, 30.6 (8.0–98.7) | 1693, 34.1 (8.0–123.4) |
| Aspartate aminotransferase, U/L | 5166, 36.2 (13.0–113.0) | 3063, 36.6 (14.0–112.4) | 2103, 35.5 (12.0–118.0) | 3649, 35.0 (13.0–110.4) | 1517, 38.9 (13.0–118.1) |
| Bilirubin, mg/dL | 5853, 0.5 (0.0–1.6) | 3481, 0.5 (0.0–1.6) | 2372, 0.5 (0.0–1.6) | 4109, 0.5 (0.0–1.6) | 1744, 0.5 (0.0–1.6) |
| Blood urea nitrogen, mg/dL | 6098, 16.0 (5.0–49.0) | 3675, 15.8 (5.0–49.0) | 2423, 16.2 (5.0–49.4) | 4287, 16.6 (5.0–51.0) | 1811, 14.5 (5.0–43.0) |
| Creatinine, mg/dL | 6097, 1.2 (0.5–3.3) | 3675, 1.2 (0.5–3.4) | 2422, 1.1 (0.5–3.1) | 4286, 1.2 (0.5–3.6) | 1811, 1.1 (0.5–2.9) |
| D‐Dimer, mg/L | 203, 1.0 (0.0–4.0) | 119, 1.0 (0.0–3.1) | 84, 1.2 (0.0–4.0) | 117, 1.2 (0.0–7.0) | 86, 0.8 (0.0–2.3) |
| International normalized ratio | 1063, 1.3 (0.9–2.9) | 409, 1.3 (0.9–3.2) | 654, 1.2 (0.9–2.5) | 774, 1.3 (0.9–3.1) | 289, 1.2 (0.9–2.6) |
| Lactate, mmol/L | 2019, 1.6 (0.7–3.7) | 1507, 1.5 (0.7–3.4) | 512, 1.7 (0.7–4.2) | 1533, 1.6 (0.7–3.8) | 486, 1.5 (0.7–3.4) |
| Platelets, K/cu mm | 6411, 205.8 (93.0–364.0) | 3927, 207.1 (98.0–366.0) | 2484, 203.8 (89.0–360.9) | 4524, 202.3 (90.1–359.0) | 1887, 214.2 (103.2–375.0) |
| Partial thromboplastin time, s | 557, 11.8 (0.8–42.5) | 163, 25.8 (0.8–52.6) | 394, 6.0 (0.9–37.8) | 420, 10.8 (0.8–43.0) | 137, 14.8 (0.9–38.2) |
| Troponin, N tested, N positive (%) | 2593, 314 (3.9) | 1219, 136 (2.7) | 1374, 178 (6.0) | 1826, 240 (4.5) | 767, 74 (2.8) |
| White blood cell count, K/cu mm | 6477, 8.1 (0.0–20.1) | 3969, 7.8 (0.0–20.6) | 2508, 8.5 (0.0–19.6) | 4563, 8.4 (0.0–21.0) | 1914, 7.3 (0.0–18.9) |
| Oxygen requirements, N (%) | |||||
| Low‐flow oxygen, <2 L/min | 501 (6.2) | 278 (5.5) | 223 (7.6) | 373 (7.0) | 128 (4.8) |
| Mid‐flow oxygen, 2–9 L/min | 333 (4.1) | 174 (3.4) | 159 (5.4) | 253 (4.7) | 80 (3.0) |
| High‐flow oxygen, >10 L/min | 171 (2.1) | 83 (1.6) | 88 (3.0) | 118 (2.2) | 53 (2.0) |
| Emergency department disposition, N (%) | |||||
| Discharged | 5686 (70.8) | 3676 (72.3) | 2010 (68.3) | 3621 (67.7) | 2065 (77.1) |
| Hospitalized | 2345 (29.2) | 1410 (27.7) | 935 (31.7) | 1731 (32.3) | 614 (22.9) |
| Intensive or intermediate care | 328 (4.1) | 226 (4.4) | 102 (3.5) | 234 (4.4) | 94 (3.5) |
| Critical care outcome | |||||
| Criteria met at time of disposition | 176 (2.2) | 85 (1.7) | 91 (3.1) | 119 (2.2) | 57 (2.1) |
| Criteria met after disposition | 326 (4.1) | 205 (4.0) | 121 (4.1) | 251 (4.7) | 75 (2.8) |
| Inpatient care outcome | |||||
| Criteria met at time of disposition | 935 (11.6) | 437 (8.6) | 498 (16.9) | 690 (12.9) | 245 (9.1) |
| Criteria met after disposition | 644 (8.0) | 360 (7.1) | 284 (9.6) | 502 (9.4) | 142 (5.3) |