Table 1 Background characteristics and clinical variables of the severe and non-severe COVID-19 patients

Age (years)

59.4 ± 18.3

70.9 ± 14.8

50.5 ± 15.6

 < 0.001

Male (gender)

306 (53.3%)

167 (66.3%)

139 (43.2%)

 < 0.001

Body mass index (kg/m²)

24.4 ± 4.9

23.7 ± 4.9

25 ± 4.8

0.002

Smoking history

 Current

52 (9.1%)

27 (10.7%)

25 (7.8%)

0.145

 Former

77 (13.4%)

27 (10.7%)

50 (15.5%)

Never

445 (77.5%)

198 (78.6%)

247 (76.7%)

Cerebrovascular accident

39 (6.8%)

37 (14.7%)

2 (0.6%)

 < 0.001

Hypertension

211 (36.8%)

125 (49.6%)

86 (26.7%)

 < 0.001

Diabetes mellitus

147 (25.6%)

105 (41.7%)

42 (13%)

 < 0.001

Chronic heart disease

79 (13.8%)

65 (25.8%)

14 (4.3%)

 < 0.001

Chronic lung disease

99 (17.2%)

34 (13.5%)

65 (20.2%)

 < 0.001

Chronic liver disease

49 (8.5%)

28 (11.1%)

21 (6.5%)

 < 0.001

Chronic kidney disease

60 (10.5%)

52 (20.6%)

8 (2.5%)

 < 0.001

Immunocompromised status

107 (18.6%)

71 (28.2%)

36 (11.2%)

 < 0.001

WBC (10³/µL)

9.1 ± 6.7

11.3 ± 9.0

7.3 ± 2.9

 < 0.001

Neutrophil (%)

73.2 ± 43.9

83 ± 50.7

65.1 ± 35.4

 < 0.001

Lymphocyte (%)

19.8 ± 12.9

10.9 ± 10.4

27.2 ± 9.7

 < 0.001

Neutrophil/lymphocyte ratio

3.8 (2–10.3)

10.4 (5.5–19.5)

2.2 (1.7–3.3)

 < 0.001

Hemoglobin (g/dL)

12.5 ± 2.4

11.4 ± 2.6

13.3 ± 1.9

 < 0.001

Platelets (10³/µL)

236.4 ± 97.5

209.4 ± 109.4

258.3 ± 80.6

 < 0.001

Serum creatinine (mg/dL)

0.8 (0.7–1.2)

1.1 (0.7–1.8)

0.8 (0.6–0.9)

 < 0.001

Ferritin (ng/mL)

378 (150.5–817)

797.5 (439–1239.3)

212 (76.5–381.5)

 < 0.001

LDH (U/L)

219.5 (182.8–285)

294 (225.3–382.3)

194 (170.3–225)

 < 0.001

CRP (mg/L)

10.9 (1.3–104.5)

106 (35.6–172.5)

1.3 (0.6–3.6)

 < 0.001

IL-6 (pg/mL)

6.6 (2.4–40.7)

31.2 (12.1–110)

2.3 (1.6–4.1)

 < 0.001

Blood cadmium (μg/L)

0.8 ± 0.5

1.0 ± 0.6

0.7 ± 0.4

 < 0.001

Blood nickel (μg/L)

1.5 ± 0.2

1.5 ± 0.3

1.5 ± 0.1

0.320

Urine cadmium/creatinine (μg/g)

 mean ± SD

5.2 ± 19.3

10.5 ± 28.2

0.9 ± 0.8

 < 0.001

 median (IQR)

1.3 (0.6–3.5)

3.8 (2.2–8.8)

0.7 (0.4–1.1)

 < 0.001

Urine nickel (μg/L)

 mean ± SD

2.9 ± 4.3

3.6 ± 6.4

2.4 ± 1.8

0.008

 median (IQR)

1.7 (1.4–2.8)

1.8 (1.4–2.9)

1.6 (1.4–2.7)

0.008

Treatment at the time of diagnosis

 Nirmatrelvir and ritonavir (Paxlovid)

55 (9.6%)

21 (8.3%)

34 (10.6%)

 < 0.001

 Molnupiravir

33 (5.7%)

22 (8.7%)

11 (3.4%)

 < 0.001

 Remdesivir

193 (33.6%)

193 (76.6%)

0 (0%)

 Dexamethasone

217 (37.8%)

217 (86.1%)

0 (0%)

 Tocilizumab

12 (2.1%)

12 (4.8%)

0 (0%)

Type of respiratory support

 Room air

322 (56.1%)

0 (0%)

322 (100%)

 Nasal cannula

51 (8.9%)

51 (20.2%)

0 (0%)

 Simple mask

27 (4.7%)

27 (10.7%)

0 (0%)

 High-flow nasal cannula

14 (2.4%)

14 (5.6%)

0 (0%)

 Nonrebreathing mask

11 (1.9%)

11 (4.4%)

0 (0%)

 Invasive mechanical ventilation

149 (26%)

149 (59.1%)

0 (0%)

Site

 Chang Gung Memorial Hospital Linkou branch

495 (86.2%)

223 (88.5%)

272 (84.5%)

0.165

 New Taipei Municipal TuCheng Hospital

79 (13.8%)

29 (11.5%)

50 (15.5%)

0.165

 Outpatients

311 (54.2%)

0 (0%)

311 (96.6%)

Hospitalized

263 (45.8%)

252 (100%)

11 (3.4%)

 < 0.001

Hospital mortality

68 (11.8%)

68 (27%)

0 (0%)