Table 5 Main meta-analyses for ever smoking of any product (or cigarettes if any product not available)^a

All

All

n

129

114

28

F

2.34 (2.27-2.40)

2.42 (2.36-2.48)

3.22 (2.95-3.52)

R

2.89 (2.63-3.17)

2.69 (2.50-2.90)

4.51 (3.38-6.02)

H, P_H

8.11, < 0.001

5.81, < 0.001

6.42, < 0.001

Sex

Male

n

49

51

13

F

2.69 (2.55-2.84)

2.87 (2.74-3.00)

5.71 (4.74-6.87)

R

3.60 (2.98-4.34)

3.18 (2.77-3.65)

5.42 (3.69-7.96)

Female

n

35

39

6

F

2.16 (2.04-2.28)

2.22 (2.11-2.32)

3.44 (2.60-4.55)

R

2.73 (2.17-3.43)

2.57 (2.28-2.89)

3.25 (2.07-5.10)

Combined

n

45

24

9

F

2.26 (2.17-2.35)

2.24 (2.15-2.33)

2.62 (2.36-2.92)

R

2.51 (2.23-2.82)

2.29 (2.05-2.57)

4.47 (2.72-7.34)

Between levels

P_B

NS

< 0.001

< 0.05

Continent

N America

n

35

38

14

F

3.21 (3.04-3.39)

2.91 (2.75-3.07)

5.33 (4.49-6.33)

R

3.48 (2.88-4.20)

3.17 (2.70-3.71)

5.32 (3.86-7.32)

Europe

n

59

60

10

F

2.09 (2.01-2.17)

2.34 (2.27-2.41)

2.19 (1.95-2.46)

R

2.79 (2.46-3.16)

2.62 (2.39-2.89)

3.13 (2.01-4.87)

Asia

n

23

9

4

F

2.26 (2.08-2.45)

2.08 (1.92-2.24)

5.76 (4.59-7.23)

R

2.73 (2.15-3.46)

2.21 (1.78-2.75)

5.59 (3.93-7.95)

Other or multicountry

n

12

7

0

F

1.91 (1.71-2.14)

2.34 (2.09-2.61)

R

2.13 (1.66-2.73)

2.09 (1.59-2.74)

Between levels

P_B

< 0.001

< 0.05

< 0.001

Publication year

Before 1980

n

25

49

13

F

3.82 (3.40-4.29)

3.02 (2.86-3.18)

5.81 (4.74-7.12)

R

3.79 (2.82-5.10)

3.22 (2.82-3.68)

5.37 (3.72-7.75)

1980-89

n

10

28

5

F

2.13 (1.80-2.50)

2.44 (2.33-2.56)

2.10 (1.86-2.37)

R

2.34 (1.79-3.05)

2.72 (2.33-3.17)

2.39 (1.49-3.82)

1990-99

n

19

17

3

F

3.75 (3.36-4.18)

2.09 (1.96-2.22)

3.14 (2.34-4.22)

R

3.31 (2.39-4.58)

2.24 (1.91-2.63)

3.14 (2.34-4.22)

2000 or later

n

75

20

7

F

2.19 (2.13-2.26)

2.19 (2.09-2.29)

5.76 (4.72-7.04)

R

2.62 (2.36-2.90)

2.19 (1.93-2.48)

5.58 (3.63-5.58)

Between levels

P_B

< 0.001

< 0.001

< 0.001

Study type

Case-control

n

16

10

0

F

2.51 (2.10-2.99)

2.35 (2.04-2.69)

R

2.95 (2.14-4.06)

2.72 (1.85-3.77)

Prospective

n

37

11

6

F

4.49 (4.12-4.89)

2.30 (2.08-2.55)

6.12 (4.77-7.85)

R

3.71 (2.94-4.69)

2.60 (2.04-3.30)

4.95 (2.72-8.99)

Cross-sectional

n

76

93

22

F

2.16 (2.10-2.22)

2.43 (2.36-2.49)

2.93 (2.67-3.22)

R

2.54 (2.32-2.80)

2.70 (2.49-2.93)

4.36 (3.19-5.96)

Between levels

P_B

< 0.001

NS

< 0.05

Outcome subtype

Mortality

n

29

3

4

F

4.50 (4.09-4.94)

4.10 (2.54-6.60)

8.24 (6.24-10.87)

R

3.95 (3.00-5.21)

5.49 (2.14-14.11)

8.24 (6.24-10.87)

Lung function (COPD) or symptoms (CB)

n

60

83

0

F

2.16 (2.09-2.23)

2.51 (2.44-2.58)

R

2.35 (2.13-2.59)

2.78 (2.55-3.03)

Other

n

40

28

24

F

2.31 (2.19-2.45)

2.11 (2.00-2.22)

2.89 (2.63-3.18)

R

3.10 (2.56-3.76)

2.31 (2.01-2.65)

4.00 (2.97-5.37)

Between levels

P_B

< 0.001

< 0.05

< 0.01

How asthma taken into account

Ignored

n

76

103

26

F

2.60 (2.52-2.70)

2.44 (2.38-2.50)

3.22 (2.94-3.52)

R

2.95 (2.62-3.32)

2.69 (2.50-2.91)

4.61 (3.43-6.19)

Excluded

n

21

7

2

F

1.83 (1.73-1.94)

1.91 (1.71-2.13)

3.22 (1.45-7.11)

R

2.35 (1.92-2.87)

2.13 (1.61-2.80)

3.20 (0.36-28.37)

Included in outcome definition

n

19

-

-

F

1.76 (1.61-1.92)

R

2.55 (2.00-3.26)

Other

n

13

4

0

F

3.68 (3.20-4.24)

5.41 (3.58-8.18)

R

3.62 (2.80-4.69)

5.37 (3.13-9.21)

Between levels

P_B

< 0.001

< 0.1

NS

Number of cases

1-50

n

23

17

6

F

4.06 (3.12-5.29)

2.70 (1.98-3.69)

2.89 (1.78-4.67)

R

4.45 (3.19-6.21)

2.70 (1.98-3.69)

2.89 (1.78-4.67)

51-100

n

29

13

9

F

2.42 (2.12-2.75)

3.71 (2.91-4.72)

2.87 (2.15-3.83)

R

2.55 (2.09-3.12)

4.15 (2.97-5.80)

3.19 (2.10-4.85)

101-200

n

30

19

5

F

2.39 (2.18-2.63)

3.07 (2.66-3.53)

7.30 (5.31-10.03)

R

2.69 (2.24-3.24)

3.48 (2.64-4.58)

7.48 (4.73-11.85)

201+

n

47

65

8

F

2.31 (2.24-2.38)

2.38 (2.32-2.44)

3.03 (2.74-3.24)

R

2.91 (2.54-3.32)

2.51 (2.31-2.72)

4.96 (2.99-8.22)

Between levels

P_B

NS

NS

NS

Analysis type

Prevalence

n

93

105

22

F

2.17 (2.11-2.23)

2.43 (2.37-2.50)

2.93 (2.67-3.22)

R

2.57 (2.35-2.81)

2.71 (2.51-2.93)

4.36 (3.19-5.96)

Onset

n

36

9

6

F

4.55 (4.17-4.96)

2.02 (1.78-2.28)

6.12 (4.77-7.85)

R

3.77 (2.98-4.78)

2.37 (1.80-3.13)

4.95 (2.72-8.99)

Between levels

P_B

< 0.001

NS

< 0.05

Smoking product

Any

n

48

61

11

F

2.60 (2.47-2.74)

2.59 (2.51-2.68)

2.51 (2.24-2.80)

R

2.99 (2.61-3.44)

2.89 (2.63-3.19)

4.16 (2.55-6.78)

Cigarettes (ignoring other products)

n

73

51

15

F

2.08 (2.01-2.15)

2.18 (2.10-2.26)

4.96 (4.26-5.78)

R

2.48 (2.23-2.76)

2.44 (2.17-2.73)

4.58 (3.33-6.30)

Cigarettes only

n

8

2

2

F

6.38 (5.61-7.24)

3.03 (2.29-4.01)

6.69 (3.43-13.05)

R

6.42 (4.22-9.78)

5.04 (1.29-19.70)

6.69 (3.43-13.05)

Between levels

P_B

< 0.001

< 0.05

< 0.01

Unexposed base^c

Never any product

n

57

70

14

F

2.95 (2.82-3.09)

2.61 (2.52-2.69)

2.75 (2.47-3.06)

R

3.44 (2.95-4.01)

2.90 (2.65-3.18)

4.76 (3.02-7.50)

Never cigarettes

n

72

44

14

F

2.05 (1.98-2.12)

2.16 (2.07-2.24)

4.62 (3.93-5.43)

R

2.47 (2.22-2.74)

2.42 (2.15-2.73)

4.28 (3.08-5.96)

Between levels

P_B

< 0.001

< 0.01

< 0.05

RR adjusted for age

Yes

n

69

63

15

F

2.46 (2.35-2.56)

2.17 (2.10-2.24)

2.70 (2.43-3.00)

R

2.97 (2.56-3.45)

2.46 (2.26-2.69)

4.44 (2.90-6.82)

No

n

60

51

13

F

2.26 (2.18-2.34)

2.78 (2.67-2.88)

4.91 (4.17-5.79)

R

2.77 (2.46-3.12)

3.03 (2.69-3.41)

4.67 (3.45-6.33)

Between levels

P_B

NS

< 0.001

< 0.05

RR adjusted for factors other than age or sex

Yes

n

34

30

6

F

2.09 (1.98-2.21)

2.28 (2.20-2.37)

2.11 (1.87-2.38)

R

2.64 (2.23-3.13)

2.41 (2.14-2.71)

2.11 (1.87-2.38)

No

n

95

84

22

F

2.43 (2.35-2.51)

2.53 (2.45-2.61)

5.26 (4.62-6.00)

R

3.00 (2.68-3.36)

2.86 (2.60-3.15)

5.02 (3.88-6.50)

Between levels

P_B

< 0.1

< 0.1

< 0.001