Table 1. Baseline characteristics and outcomes of the derivation and validation cohorts.
| Characteristics | Derivation cohort | Validation cohort | ||
|---|---|---|---|---|
| Cases admitted from home | Cases admitted from nursing home | Cases admitted from home | Cases admitted from nursing home | |
| (n = 19,746) | (n = 14,359) | (n = 6,262) | (n = 6,352) | |
| Age, mean (SD) | 84.63 (7.56) | 86.63 (7.43) | 84.74 (7.87) | 87.16 (7.37) |
| Male, n (%) | 12884 (65.2) | 7111 (49.5) | 4198 (67.0) | 3108 (48.9) |
| BMI, median [IQR] | 18.94 [16.55, 21.63] | 18.06 [15.94, 20.41] | 19.12 [16.66, 21.83] | 18.02 [15.86, 20.45] |
| Assistance needs with ≥ 1 ADL functions, n (%) | 18271 (92.5) | 14187 (98.8) | 5767 (92.1) | 6309 (99.3) |
| Malnutrition, n (%) | 7074 (35.8) | 6745 (47.0) | 2415 (38.6) | 3259 (51.3) |
| Consciousness level, n (%) | ||||
| Japan coma scale: 0 | 10598 (53.7) | 5469 (38.1) | 3370 (53.8) | 2134 (33.6) |
| Japan coma scale: 1–3 | 6635 (33.6) | 5720 (39.8) | 2133 (34.1) | 2582 (40.6) |
| Japan coma scale: 10–30 | 1728 (8.8) | 2308 (16.1) | 538 (8.6) | 1168 (18.4) |
| Japan coma scale: 100–300 | 785 (4.0) | 862 (6.0) | 221 (3.5) | 468 (7.4) |
| Emergency hospitalization, n (%) | 14518 (73.5) | 10654 (74.2) | 3343 (53.4) | 3738 (58.8) |
| Hospitalization for aspiration pneumonia within 90 days, n (%) | 1584 (8.0) | 1319 (9.2) | 675 (10.6) | 675 (10.6) |
| Comorbidities, n (%) | ||||
| Congestive heart failure | 3110 (15.8) | 2317 (16.1) | 1076 (17.2) | 1179 (18.6) |
| Diabetes mellitus | 3472 (17.6) | 1985 (13.8) | 1126 (18.0) | 883 (13.9) |
| Metastatic cancer | 327 (1.7) | 90 (0.6) | 91 (1.5) | 35 (0.6) |
| Cerebrovascular disease | 3893 (19.7) | 3486 (24.3) | 1538 (24.6) | 2002 (31.5) |
| Dementia | 5070 (25.7) | 5755 (40.1) | 1579 (25.2) | 2658 (41.8) |
| Pressure ulcers | 543 (2.7) | 569 (4.0) | 153 (2.4) | 210 (3.3) |
| Pleural effusion | 1108 (5.6) | 863 (6.0) | 296 (4.7) | 355 (5.6) |
| Oxygen administration, n (%) | 11958 (60.6) | 9336 (65.0) | 3602 (57.5) | 4191 (66.0) |
| Respiratory support, n (%) | 486 (2.5) | 253 (1.8) | 227 (3.6) | 179 (2.8) |
| Vasopressor administration, n (%) | 500 (2.5) | 353 (2.5) | 191 (3.1) | 211 (3.3) |
| Sputum suctioning, n (%) | 8194 (41.5) | 8038 (56.0) | 2217 (35.4) | 3472 (54.7) |
| Outcomes | ||||
| Home discharge, n (%) | 10760 (54.5) | – | 3480 (55.6) | – |
| Discharge to nursing home or home, n (%) | – | 7071 (49.2) | – | 3250 (51.2) |
| Length of stay, median [IQR] | 18 [11, 31] | 20 [13, 33] | 17 [10, 29] | 18 [12, 30] |
| In-hospital mortality, n (%) | 3324 (16.8) | 2879 (20.1) | 774 (12.4) | 1118 (17.6) |
ADL were defined as the 10 components of the Barthel index (feeding, bathing, grooming, dressing, bowel control, bladder control, toilet use, transfers from bed to chair, mobility on level surfaces, and stairs). Malnutrition was defined as a serum albumin level of 3.0 g/dL or less, parenteral nutrition, or tube feeding at admission. Respiratory support included high-flow nasal cannula, noninvasive ventilation, and invasive mechanical ventilation. Abbreviations: SD, standard deviation; IQR, interquartile range; BMI, body mass index; ADL, activities of daily living.