Table 4 Subgroup analysis for the association between age and mortality risk of severe pneumonia

Geographic region

5.30 (2.96, 7.65)

 < 0.00001

0.92

Africa

3

8.75 (3.13, 14.38)

0.002

0.62

Asia

6

2.92 (0.51, 5.33)

0.02

0.88

Europe

2

7.43 (4.82, 10.04)

 < 0.00001

0.56

North America

2

4.69 (− 0.89, 10.27)

0.10

0.45

Study design

6.36 (3.41, 9.31)

 < 0.0001

0.96

Retrospective

8

7.00 (2.52, 11.47)

0.0002

0.58

Prospective

6

5.42 (2.47, 8.37)

0.003

0.93

ICU admission

6.36 (3.41, 9.31)

 < 0.0001

0.73

ICU

7

5.86 (1.20, 10.51)

 < 0.0001

0.96

Not ICU

8

6.80 (3.40, 10.21)

0.01

0.93

Sex ratio (male/female)

6.12 (3.10, 9.15)

 < 0.0001

0.93

 ≤ 2

7

7.21 (2.62, 11.80)

0.002

0.83

 > 2

7

5.10 (0.75, 9.45)

0.02

0.96

Sample size

6.12 (3.10, 9.15)

 < 0.0001

0.93

 ≤ 100

5

5.79 (0.43, 11.15)

0.03

0.80

100 ~ 200

5

8.37 (5.09, 11.65)

 < 0.00001

0.70

 > 200

4

3.31 (− 0.42, 7.03)

0.08

0.86