Table 3 Subgroup analysis based on study location, type of participants and population size

1. Study location

 1.1 Asia

28

39,501 (72%)

1.43, P=0.01

54.7%

1.32, P=0.21

1.3, P=0.36

1.07, P=0.85

 Sub-subgroups for studies in Asia:

  1.1.1 GI group older than non-GI group

7

32,894

2.43, P<0.01

66.9%

  1.1.2 GI group younger than non-GI group

6

3048

1.2, P=0.29

15.8%

 1.2 America

12

8324 (15%)

0.64, P<0.01

42.7%

0.81, P=0.37

0.84, P=0.8

NA

 Sub-subgroups for studies in America:

  1.2.1 GI group older than non-GI group

NA

NA

NA

NA

  1.2.2 GI group younger than non-GI group

5

3990

0.55, P<0.01

30.6%

 1.3 Europe

10

2653 (5%)

0.4, P<0.01

77%

0.51, P=0.07

0.7, P=0.51

0.61, P=0.76

 Sub-subgroups for studies in Europe:

  1.3.1 GI group older than non-GI group

NA

NA

NA

NA

  1.3.2 GI group younger than non-GI group

3

805

0.23, P<0.01

84%

 1.4 Other

3

4767(8%)

0.92, P=0.83

87.8%

0.93, P=0.92

NA

NA

2. Only include critically ill patients?

 3.1 Yes

6

1124(2%)

1.42, P=0.36

74.6%

1.3, P=0.45

0.92, P=0.71

0.75, P=0.45

 3.2 No

47

54,121 (98%)

0.83, P=0.1

78.3%

0.92, P=0.69

1.37, P=0.28

2.67, P=0.05

3. Population size

 4.1 <500

36

7436 (13%)

0.93, P=0.66

72.1%

1.05, P=0.82

1.19, P=0.51

1.04, P=0.92

 4.2 >=500

17

47,809 (87%)

0.84, P=0.25

85.7%

0.94, P=0.83

1.16, P=0.68

NA

4. Average age of GI group and non-GI group

 4.1 GI group older than non-GI group

8

33,294 (60%)

1.89, P=0.02

69%

 4.2 GI group younger than non-GI group

14

7843 (14%)

0.61, P=0.01

80%

 4.3 Unknown

31

14,058 (26%)

0.89, P=0.36

64%