Table 2 The risk factors for developing severe COVID–19 cases based on surveillance data from January 19 to March 9 in 2020 in China

Gender

 Female

1

1

 Male

1.33 (1.2–1.5)

1.34 (1.2–1.5)

Age group, years

 0–19

1

1

 20–39

7.63 (3.6–16.2)

3.90 (1.8–8.4)

 40–59

17.62 (8.3–37.2)

7.63 (3.6–16.3)

 ≥ 60

48.46 (22.9–102.5)

20.42 (9.5–43.7)

Living area

 Rural

1

1

 Urban

1.15 (1.0–1.3)

0.94 (0.8–1.1)

Region

 East

1

1

 Central

1.14 (1.0–1.3)

1.12 (1.0–1.3)

 West

1.18 (1.0–1.4)

1.40 (1.2–1.6)

The symptom onset to diagnosis, days

 0–2

1

1

 3–5

1.84 (1.6–2.2)

1.41 (1.2–1.7)

 6–8

2.75 (2.4–3.2)

1.79(1.5–2.1)

 ≥ 9

2.98 (2.5–3.5)

1.91(1.6–2.3)

Fever

 No

1

1

 Yes

3.14 (2.7–3.6)

2.30(2.0–2.7)

Fatigue, joint or muscle soreness

 No

1

1

 Yes

1.94 (1.7–2.2)

1.33(1.2–1.5)

Cough or respiratory symptoms

 No

1

1

 Yes

1.75 (1.6–1.9)

1.40(1.2–1.6)

Gastrointestinal symptoms

 No

1

1

 Yes

1.48 (1.3–1.8)

1.09(0.9–1.3)

Headache

 No

1

1

 Yes

1.31 (1.1–1.5)

1.15(1.0–1.4)

Conjunctival congestion

 No

1

 Yes

1.47 (0.5–4.4)

White blood cell count (10⁹/L)^a

  4–10

1.0

1

 < 4

1.06 (0.9–1.2)

1.03(0.9–1.2)

 > 10

1.76 (1.4–2.3)

1.47(1.1–2.0)

 Unavailable

0.51 (0.4–0.6)

0.54(0.2–1.5)

Lymphocyte count (10⁹/L)^b

 0.8–3.5

1

1

 < 0.8

2.41 (2.1–2.7)

1.28 (1.1–1.5)

 > 3.5

1.20 (0.9–1.6)

1.22 (0.9–1.7)

 Unavailable

0.62 (0.5–0.8)

1.72 (0.8–3.6)

Lymphocyte percentage(%)^c

 20–40

1

1

 < 20

2.14 (1.9–2.4)

1.19 (1.0–1.4)

 > 40

0.63 (0.5–0.8)

0.77 (0.60–1.0)

 Unavailable

0.63 (0.5–0.8)

1.22 (0.4–3.8)

Neutrophil percentage (%)^d

 40–75

1

1

 < 40

1.09 (0.9–1.3)

1.27 (1.0–1.6)

 > 75

2.57 (2.3–2.9)

1.55 (1.3–1.9)

 Unavailable

0.62 (0.5–0.8)

0.98 (0.3–2.8)

Abnormal X-ray

 No

1

1

 Yes

1.53 (1.3–1.8)

1.29 (1.1–1.6)

 Unavailable

0.99 (0.9–1.1)

0.96 (0.8–1.1)

Abnormal CT imaging

 No

1

1

 Yes

3.21 (2.4–4.3)

1.57(1.2–2.1)

 Unavailable

2.14 (1.6–2.9)

1.53(1.1–2.2)

Underlying diseases

 No

1

1

 Yes

3.08 (2.8–3.4)

0.88 (0.7–1.1)

Diabetes

 No

1

1

 Yes

4.73(4.0–5. 7)

1.96 (1.6–2.4)

Hypertension and other cardiovascular and cerebrovascular diseases

 No

1

1

 Yes

3.68 (3.3–4.2)

1.46 (1.2–1.8)

Lung diseases

 No

1

1

 Yes

2.88 (2.2–3.7)

1.42 (1.1–1.9)

Chronic liver diseases

 No

1

 Yes

1.12 (0.6–2.0)

Chronic kidney diseases

 No

1

1

 Yes

5.97 (3.5–10.3)

2.50 (1.4–4.6)

Exposure history

 No

1

1

 Yes

0.53 (0.5–0.6)

0.63 (0.5–0.8)