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Table 3 Subgroup and sensitivity analyses

From: Association between coffee consumption and risk of bladder cancer in a meta-analysis of 16 prospective studies

 

Highest vs. lowest consumption

Each 1 cup/d increment

N

RR (95% CI)

I2 (%)

P-diff

N

RR (95% CI)

I2 (%)

P-diff

Subgroup analyses

Geographic region

  US

7

1.10 (0.92–1.32)

50.4

Ref.

7

1.01 (0.97–1.04)

70.0

Ref.

  Europe

6

1.13 (0.98–1.31)

0

0.60

5

1.02 (0.99–1.04)

0

0.55

  Japan

3

0.81 (0.57–1.16)

23.1

0.23

3

0.92 (0.75–1.14)

65.3

0.30

Duration of follow-up

   ≥ 10 yr

12

1.08 (0.95–1.23)

35.9

 

11

1.01 (0.98–1.04)

62.6

 

   < 10 yr

4

1.04 (0.81–1.35)

31.4

0.86

4

1.00 (0.95–1.04)

42.3

0.67

No. of participants

   ≥ 50,000

8

1.02 (0.91–1.15)

28.9

 

8

1.00 (0.98–1.03)

61.1

 

   < 50,000

8

1.21 (0.96–1.51)

28.9

0.26

7

1.04 (0.97–1.13)

52.0

0.67

Sex

  Men

10

1.16 (1.00–1.35)

21.5

 

9

1.01 (0.98–1.05)

42.0

 

  Women

7

0.90 (0.59–1.37)

63.6

0.37

6

0.98 (0.89–1.08)

56.0

0.76

No. of cases

   ≥ 200

10

1.02 (0.92–1.13)

19.0

 

10

1.00 (0.98–1.02)

57.3

 

   < 200

6

1.38 (1.05–1.81)

12.0

0.064

5

1.12 (1.04–1.21)

0

0.037

% Male cases

   ≥ 75%

6

1.10 (0.95–1.26)

4.1

 

6

1.02 (0.94–1.10)

69.3

 

   < 75%

9

1.10 (0.92–1.30)

37.6

0.98

7

1.01 (0.99–1.04)

18.5

0.87

% Current smoker

   ≥ 25%

8

1.02 (0.82–1.25)

26.3

 

7

1.00 (0.94–1.07)

52.6

 

   < 25%

8

1.10 (0.96–1.26)

40.5

0.60

8

1.01 (0.98–1.03)

63.6

0.98

Smoking status

  Never

6

1.15 (0.79–1.67)

56.5

Ref.

6

1.02 (0.95–1.09)

58.0

Ref.

  Former

3

1.18 (0.92–1.52)

55.5

0.80

3

1.01 (0.97–1.05)

69.7

0.99

  Never/former

6

1.20 (0.93–1.56)

61.7

0.71

6

1.03 (0.98–1.08)

76.3

0.80

  Current

3

1.19 (0.97–1.46)

0

0.72

3

1.04 (1.01–1.07)

0

0.50

  Former/current

4

1.12 (0.88–1.43)

33.3

0.81

4

1.01 (0.95–1.07)

38.4

0.73

Statistical adjustment

Smokinga

  Poorer

3

1.48 (1.14–1.93)

0

Ref.

3

1.08 (1.02–1.15)

8.9

Ref.

  Moderate

8

1.00 (0.80–1.26)

31.7

0.058

7

0.98 (0.90–1.07)

60.5

0.17

  Better

5

1.03 (0.93–1.13)

0

0.042

5

1.00 (0.98–1.02)

49.7

0.055

Alcohol drinking

  No

12

1.13 (1.01–1.26)

10.4

 

11

1.02 (0.99–1.04)

34.5

 

  Yes

4

0.91 (0.74–1.13)

34.2

0.067

4

0.98 (0.92–1.04)

68.8

0.075

Education

  No

10

1.18 (1.00–1.40)

19.6

 

9

1.03 (0.99–1.07)

44.1

 

  Yes

6

0.99 (0.87–1.13)

31.5

0.14

6

0.99 (0.96–1.03)

69.5

0.33

 Physical activity

  No

13

1.10 (0.95–1.29)

33.4

 

12

1.01 (0.97–1.05)

53.6

 

  Yes

3

1.02 (0.88–1.17)

24.4

0.48

3

1.00 (0.97–1.04)

75.7

0.90

BMI

  No

12

1.15 (1.02–1.29)

5.1

 

12

1.02 (0.99–1.05)

33.9

 

  Yes

4

0.92 (0.74–1.14)

52.9

0.099

3

0.98 (0.93–1.03)

80.7

0.31

Diabetes

  No

13

1.10 (0.96–1.25)

27.1

 

12

1.01 (0.98–1.04)

43.2

 

  Yes

3

0.97 (0.73–1.29)

60.4

0.57

3

0.99 (0.92–1.05)

78.4

0.78

Family history of cancer

  No

14

1.10 (0.96–1.27)

27.9

 

13

1.01 (0.98–1.05)

49.9

 

  Yes

2

0.99 (0.82–1.21)

57.6

0.41

2

1.00 (0.96–1.04)

87.0

0.74

Energy intake

  No

14

1.08 (0.96–1.23)

35.3

 

13

1.01 (0.99–1.04)

59.0

 

  Yes

2

1.00 (0.74–1.36)

28.9

0.74

2

0.98 (0.91–1.04)

51.3

0.43

Fruit/vegetable consumption

  No

12

1.13 (0.97–1.33)

32.1

 

11

1.02 (0.98–1.06)

51.5

 

  Yes

4

1.00 (0.88–1.14)

16.5

0.29

4

1.00 (0.97–1.03)

72.1

0.54

Tea consumption

  No

11

1.15 (1.02–1.29)

11.4

 

10

1.02 (0.99–1.05)

40.8

 

  Yes

5

0.92 (0.96–1.20)

12.3

0.042

5

0.99 (0.96–1.03)

62.1

0.26

Sensitivity analysis

 Excluding 1 studyb

15

1.10 (0.98–1.23)

22.4

 

14

1.01 (0.99–1.04)

47.0

 

 Excluding 2 studiesc

14

1.10 (0.97–1.25)

27.9

 

13

1.01 (0.98–1.04)

51.0

 
  1. “N” indicates the number of studies included in the analyses; “P-diff” indicates P values for differences between subgroup population (derived using meta-regression analyses)
  2. a Poorer adjustment for smoking: no adjustment for smoking or adjustment for smoking status only; moderate adjustment for smoking: adjustment for smoking status in addition smoking frequency (e.g. cigarettes smoked per day, or pack-years of smoking) either continuously or categorically; better adjustment for smoking: adjustment for smoking status, smoking frequency, in addition to smoking duration or lifetime smoking intensity. One study (Gaspstur, 2017) that reported results only for nonsmokers (never and former smokers) and adjusted for smoking history for former smokers was included in the “better” group. Another study (Hashemian, 2019) that included totally current smokers and adjusted for both smoking frequency and duration was included in the “moderate group” (this study further examined coffee-bladder cancer association by smoking frequency and did not find group differences in the association)
  3. b Excluding one study (Gaspstur, 2017) in which the study outcome was bladder cancer mortality, and all analyzed participants were never or former smokers
  4. c In addition to the above-mentioned study (Gaspstur, 2017), further excluding another study (Hashemian, 2019) in which all participants were current smokers
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Nutrition & Metabolism

ISSN: 1743-7075

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