Table 6 Subgroup analysis of Incidence.

From: The effect of metformin therapy on incidence and prognosis in prostate cancer: A systematic review and meta-analysis

Items

Test for Heterogeneity

Include Study

Test for Overall effect

HR

95% CI

I 2

P

Z

p

Study region

USA/Canada

64%

0.02

6

0.63

0.53

0.95

0.82 to 1.11

Europe

37%

0.19

4

1.08

0.28

0.91

0.78 to 1.08

Asia

/

/

1

30.05

<0.00001

0.23

0.21 to 0.25

Australia

/

/

1

2.54

0.01

2.16

1.19 to 3.91

Study design

Prospective

54%

0.11

3

0.45

0.66

0.94

0.73 to 1.22

Retrospective

99%

<0.00001

9

0.64

0.53

0.84

0.48 to 1.45

Sample size

<10000

78%

0.004

4

0.03

0.97

1.01

0.64 to 1.58

 ≥ 10000

99%

<0.00001

8

0.79

0.43

0.80

0.46 to 1.39

Race

African American

26%

0.24

2

0.45

0.65

1.04

0.88 to 1.23

Latino/Hispanic

94%

<0.0001

2

0

1.00

1.00

0.40 to 2.52

Non-Hispanic while

49%

0.16

2

2.33

0.02

0.86

0.76 to 0.98

Asian

100%

<0.00001

2

0.85

0.4

0.51

0.11 to 2.43

Gleason of PCa

Gleason ≥7

0%

0.38

2

1.76

0.08

1.25

0.98 to 1.59

Gleason <7

/

/

1

0.03

0.97

1.01

0.57 to 1.80

Cumulative dose of Metformin

First tertile of metformin use

90%

<0.0001

3

0.89

0.37

0.88

0.67 to 1.16

Second tertile of metformin ues

98%

<0.00001

3

1.16

0.25

0.7

0.39 to 1.8

Third tertile of metformin use

99%

<0.00001

3

1.15

0.25

0.53

1.18 to 1.56

Duration of metformin use

<2 yr

82%

0.0002

5

1.28

0.20

0.86

0.69 to 1.08

2–5 yr

96%

<0.00001

4

0.84

0.40

0.82

0.50 to 1.32

≥5 yr

98%

<0.00001

4

1.09

0.28

0.59

0.23 to 1.53

Diabetic only

Yes

99%

<0.00001

9

0.60

0.55

0.84

0.48 to 1.48

No

56%

0.10

3

0.71

0.47

0.92

0.75 to 1.15

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