Table 1. Baseline demographic and clinical characteristics.
| Characteristics | Overall cohort (n = 3,060) | Disease severity on admissiona | P value | |||
|---|---|---|---|---|---|---|
| 1–2 (n = 2,585) | 3–4 (n = 141) | 5–8 (n = 55) | ||||
| Age, yrb | 43 (26–57) | 40 (25–54) | 63 (55–76) | 70 (61–79) | < 0.001 | |
| < 5 | 15/3,058 (0.5) | 13/2,583 (0.5) | 1/141 (0.7) | 0/55 (0.0) | < 0.001d | |
| 5–14 | 49/3,058 (1.6) | 46/2,583 (1.8) | 0/141 (0.0) | 0/55 (0.0) | ||
| 15–44 | 1,515/3,058 (49.5) | 1,392/2,583 (53.9) | 10/141 (0.4) | 1/55 (1.8) | ||
| 45–64 | 1,081/3,058 (35.4) | 885/2,583 (34.3) | 66/141 (46.8) | 16/55 (29.1) | ||
| ≥ 65 | 398/3,058 (13.0) | 247/2,583 (9.6) | 64/141 (45.4) | 38/55 (69.1) | ||
| Male | 1,334/3,059 (43.6) | 1,122/2,584 (43.4) | 82/141 (58.2) | 30/55 (54.6) | 0.001 | |
| Time from illness onset to hospital admission, daysc | n = 2,710 | n = 2,280 | n = 130 | n = 45 | 0.546 | |
| 5 (2–9) | 4 (2–9) | 4 (1–9) | 7 (3–10) | |||
| Vital signs on admission | ||||||
| Respiratory rate, ≥ 22 per min | 194/2,895 (6.5) | 121/2,525 (4.8) | 18/139 (13.0) | 36/53 (67.9) | < 0.001 | |
| Pulse, ≥ 120 beats per min | 77/3,009 (2.6) | 61/2,546 (2.4) | 3/140 (2.1) | 6/55 (10.9) | < 0.001d | |
| Systolic blood pressure, ≤ 100 mmHg | 121/2,992 (4.0) | 89/2,529 (3.5) | 5/140 (3.6) | 7/55 (12.7) | 0.002d | |
| Symptoms on admission | ||||||
| Altered mental status | 7/2,944 (0.2) | 1/2,515 (0.0) | 2/132 (2.3) | 2/34 (5.9) | < 0.001d | |
| History of fever | 851/2,954 (28.8) | 652/2,516 (25.9) | 88/131 (67.2) | 30/42 (70.4) | < 0.001 | |
| Cough | 1,204/2,949 (40.8) | 999/2,518 (39.7) | 70/131 (53.4) | 20/35 (57.1) | 0.001 | |
| Sputum | 761/2,943 (25.9) | 636/2,515 (25.3) | 55/130 (42.3) | 15/34 (44.1) | < 0.001 | |
| Rhinorrhea | 357/2,933 (12.2) | 322/2,513 (12.8) | 8/127 (6.3) | 3/31 (9.7) | 0.085d | |
| Sore throat | 592/2,923 (20.3) | 515/2,504 (20.6) | 22/125 (17.6) | 7/33 (21.2) | 0.720 | |
| Dyspnea | 217/2,939 (7.4) | 121/2,508 (4.8) | 46/130 (35.4) | 26/37 (70.3) | < 0.001 | |
| Myalgia | 570/2,929 (19.5) | 467/2,510 (18.6) | 39/126 (31.0) | 13/32 (40.6) | < 0.001 | |
| Diarrhea | 209/2,927 (7.1) | 173/2,506 (6.9) | 16/128 (12.5) | 3/34 (8.8) | 0.054 | |
| Nausea or vomiting | 80/2,926 (2.7) | 61/2,505 (2.4) | 7/128 (5.5) | 2/32 (6.3) | 0.049d | |
| Comorbidity | ||||||
| Diabetes | 253/3,015 (8.4) | 161/2,551 (6.3) | 35/140 (25.0) | 20/55 (36.4) | < 0.001 | |
| Hypertension | 477/3,014 (15.8) | 331/2,551 (13.0) | 61/139 (46.0) | 27/55 (49.1) | < 0.001 | |
| Chronic heart disease | 68/2,898 (2.3) | 52/2,506 (2.1) | 6/138 (4.4) | 5/54 (9.3) | 0.004d | |
| Asthma | 56/2,958 (1.9) | 45/2,550 (1.8) | 5/140 (3.6) | 3/55 (5.5) | 0.048d | |
| Chronic kidney disease | 28/3,013 (0.9) | 10/2,549 (0.4) | 12/140 (8.6) | 2/55 (3.6) | < 0.001d | |
| Malignancy | 47/3,012 (1.6) | 30/2,549 (1.2) | 8/140 (5.7) | 6/55 (10.9) | < 0.001d | |
| Dementia | 65/2,621 (2.5) | 31/2,187 (1.4) | 20/127 (15.8) | 7/55 (12.7) | < 0.001d | |
| Obesity (BMI, ≥ 30 kg/m2) | 152/2,976 (5.1) | 133/2,519 (5.3) | 6/138 (4.4) | 755 (12.7) | 0.084 | |
| Underweight (BMI, < 18.5 kg/m2) | 336/2,976 (11.3) | 288/2,519 (11.4) | 18/138 (13.0) | 9/55 (16.4) | ||
| Current smoker | 195/2,769 (7.0) | 184/2,359 (7.8) | 6/112 (5.4) | 2/43 (4.7) | 0.483 | |
| Infiltration in chest X-ray on admission | < 0.001 | |||||
| None | 1,749/2,557 (68.4) | 1,541/2,131 (72.3) | 22/119 (18.5) | 2/52 (3.9) | ||
| Unilateral | 356/2,557 (13.9) | 293/2,131 (13.8) | 36/119 (30.3) | 1/52 (1.9) | ||
| Bilateral | 452/2,557 (17.7) | 297/2,131 (13.9) | 61/119 (51.3) | 49/52 (94.2) | ||
Data are presented as median (interquartile range) or number (%), unless otherwise indicated.
BMI = body mass index, ECMO = extracorporeal membrane oxygenation.
a1, no limitation of daily activities; 2, limitation of daily activities but no need for supplemental oxygen therapy; 3, need for supplemental oxygen therapy via nasal cannula; 4, need for supplemental oxygen therapy via facial mask; 5, need for high-flow supplemental oxygen therapy or non-invasive mechanical ventilation; 6, need for invasive mechanical ventilation; 7, multi-organ failure or need for ECMO therapy; 8, death. Patients with no disease severity score on admission day (279, 9.1%) were excluded from this analysis; bData regarding age were missing for 2 patients (0.1%); cData regarding illness onset were missing for 350 patients (11.4%); dFisher's exact test.