Table 1 Demographic, co-morbidities and clinical characteristics of the patients

Age (years)

37 (30.7 to 52)

42 (33.5 to 55.5)

33 (18 to 35)

0.009

57 (38.5 to 66)

0.12

Sex ratio (male/female)

16/16

9/12

7/4

0.4

8/12

1

Underlying disease

   Cardiovascular disease

8 (25%)

6/21

2/11

0.6

8/20

0.5

   Asthma/COPD

10 (31.25%)

8/21

2/11

0.4

12/20

0.2

   Obesity (BMI > 30)

13 (40.6%)

12/21

1/11

0.01

3/20

0.01

   Type 1 or 2 diabetes

2 (6.3%)

2/21

0

1/20

1

   Esquizophrenia

3 (9.3%)

3/21

0

0

   Cancer

3 (9.3%)

1/21

2/11

0.2

6/20

0.044

Pregnancy

3 (9.3%)

3/21

0

0

Interval between symptom onset and hospital admission (days)

4.5 (2 to 7)

6 (3.5 to 8.5)

2 (2 to 3)

0.001

2 (0 to 3)

0.01

Presenting symptoms

   Fever > 38°C

28 (87.5%)

18/21

10/11

1

18/20

1

   Cough

32 (100%)

21/21

11/11

2/20

   Dyspnea

25 (78%)

21/21

4/11

20/20

   Myalgia

24 (75%)

14/21

10/11

0.2

0

SOFA score

6.1 (± 3.29)

7.2 (± 4.2)

0.5

APACHE II score

12.6 (± 6.62)

15.14 (± 6.36)

16.3 (± 6.03)

0.5

Respiratory condition

   SaO₂ < 94%

23 (71.8%)

21/21

2/11

20/20

   PaO₂:FiO₂ ratio

1.96 (± 0.83)

NA

1.72 (± 0.68)

0.28

   Mechanical ventilation

11 (34.3%)

11/21

0

12/20

0.7

   Non-invasive ventilation

10 (31.3%)

10/21

0

8/20

0.7

Initial chest X-ray scan

   Extensive bilateral multilobar infiltrates

21 (65.6%)

21/21

0

20/20

Complications

   Secondary bacterial pneumonia

3 (9.4%)

2/21

1/11

4/20

0.4

   Pneumothorax

3 (9.4%)

3/21

0

2/20

1

   Encephalitis

1 (3.1%)

1/21

0

0

   Acute renal failure requiring renal replacement therapy

4 (12.5%)

4/21

0

3/20

1

Length of hospital stay (days)

10 (7 to 12.7)

11 (10 to 14)

6 (6 to 9)

< 0.001

18 (13 to 41)

0.005

ICU length of stay (days)

4.5 (1 to 7.5)

7 (5 to 9)

0

16.5 (1 to 33)

0.3

In-hospital death

7 (21.8%)

7/21

0

3/20

0.2