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

From: Systematic review with meta-analysis of the epidemiological evidence in the 1900s relating smoking to lung cancer

Characteristic

Level

Statisticb

All lung cancerc

Squamousd

Adenoe

All

All

n

328

102

107

  

F

4.22 (4.16-4.28)

9.52 (8.94-10.13)

3.44 (3.27-3.61)

  

R

5.50 (5.07-5.96)

10.47 (8.88-12.33)

2.84 (2.41-3.35)

  

H, PH

22.84, p < 0.001

5.17, p < 0.001

8.78, p < 0.001

  

PE

p < 0.001

NS

p < 0.01

Sex

Male

n

171

49

51

  

F

3.74 (3.67-3.82)

10.74 (9.82-11.74)

4.09 (3.76-4.44)

  

R

6.18 (5.49-6.95)

11.98 (9.68-14.82)

3.55 (2.83-4.45)

 

Female

n

108

42

45

  

F

3.95 (3.86-4.05)

8.86 (8.05-9.75)

3.27 (3.05-3.50)

  

R

4.43 (3.84-5.10)

8.97 (6.95-11.57)

2.32 (1.78-3.02)

 

Combined

n

49

11

11

  

F

8.26 (7.94-8.60)

7.04 (5.76-8.60)

2.29 (1.93-2.71)

  

R

6.09 (4.98-7.44)

10.70 (4.89-23.40)

2.52 (1.56-4.08)

 

Between levels

PB

<0.01

NS

<0.05

Location

North America

n

116

38

40

  

F

8.86 (8.63-9.10)

12.69 (11.63-13.84)

5.75 (5.36-6.16)

  

R

7.49 (6.78-8.27)

13.42 (10.45-17.24)

4.37 (3.48-5.48)

 

United Kingdom

n

29

4

4

  

F

5.22 (4.72-5.78)

4.75 (3.00-7.51)

2.74 (1.52-4.94)

  

R

5.83 (4.54-7.49)

6.27 (2.49-15.83)

2.68 (1.31-5.47)

 

Scandinavia

n

32

7

7

  

F

6.43 (5.88-7.04)

8.67 (5.88-12.78)

2.04 (1.49-2.78)

  

R

6.39 (5.29-7.71)

8.62 (4.81-15.43)

2.05 (1.37-3.06)

 

Other Europe

n

50

15

15

  

F

5.55 (5.22-5.90)

6.56 (5.72-7.52)

2.30 (1.99-2.65)

  

R

6.09 (4.95-7.51)

8.87 (5.50-14.31)

2.72 (2.01-3.68)

 

China

n

51

12

12

  

F

2.77 (2.72-2.83)

5.65 (4.71-6.78)

1.48 (1.28-1.70)

  

R

2.69 (2.50-2.88)

6.39 (4.73-8.63)

1.48 (1.28-1.70)

 

Japan

N

18

8

11

  

F

3.19 (2.91-3.49)

13.94 (9.71-20.00)

1.74 (1.47-2.06)

  

R

3.21 (2.68-3.85)

14.54 (9.78-21.62)

1.80 (1.34-2.41)

 

Other Asia

N

18

12

12

  

F

3.79 (3.41-4.20)

7.87 (6.31-9.81)

1.88 (1.56-2.26)

  

R

3.76 (2.72-5.18)

8.02 (5.54-11.60)

1.87 (1.29-2.71)

 

Other or multiregion

n

14

6

6

  

F

6.25 (5.45-7.16)

16.70 (10.07-27.70)

4.20 (2.91-6.06)

  

R

7.41 (5.72-9.60)

16.70 (10.07-27.70)

4.20 (2.91-6.06)

 

Between levels

PB

<0.001

<0.01

<0.001

Start year of study

Before 1960

n

54

14

14

  

F

3.96 (3.71-4.23)

4.35 (3.66-5.18)

1.64 (1.27-2.10)

  

R

4.67 (3.75-5.82)

5.89 (3.89-8.92)

1.64 (1.27-2.10)

 

1960-69

n

52

14

14

  

F

5.16 (4.88-5.45)

11.87 (9.75-14.44)

4.38 (3.78-5.08)

  

R

5.45 (4.60-6.46)

12.88 (7.71-21.52)

3.62 (2.00-6.54)

 

1970-79

n

71

26

31

  

F

4.58 (4.34-4.82)

8.76 (7.74-9.92)

2.47 (2.21-2.76)

  

R

5.05 (4.27-5.96)

10.08 (7.21-14.09)

2.69 (2.14-3.37)

 

1980-89

n

114

40

40

  

F

4.11 (4.04-4.17)

11.42 (10.46-12.47)

4.17 (3.90-4.45)

  

R

5.95 (5.18-6.83)

11.74 (9.40-14.66)

3.23 (2.48-4.20)

 

1990 or later

n

37

8

8

  

F

5.28 (4.83-5.77)

12.39 (8.51-18.05)

1.76 (1.44-2.17)

  

R

6.22 (4.89-7.92)

12.21 (7.56-19.72)

1.99 (1.40-2.83)

 

Between levels

PB

NS

<0.1

<0.01

Study type

Case–control

n

262

93

98

  

F

4.12 (4.06-4.18)

9.46 (8.89-10.08)

3.41 (3.24-3.59)

  

R

5.32 (4.87-5.82)

10.31 (8.70-12.22)

2.78 (2.33-3.32)

 

Prospectivef

n

66

9

9

  

F

6.01 (5.69-6.34)

12.23 (8.00-18.69)

3.95 (3.11-5.01)

  

R

6.24 (5.34-7.28)

12.78 (7.29-22.41)

3.66 (2.67-5.03)

 

Between levels

PB

<0.1

NS

NS

National cigarette tobacco type

Virginia

n

50

9

9

  

F

5.60 (5.22-6.00)

12.69 (9.36-17.20)

4.36 (3.48-5.48)

  

R

6.24 (5.16-7.54)

13.80 (6.53-29.17)

4.37 (3.01-6.34)

 

Blended

n

225

80

85

  

F

7.48 (7.32-7.65)

10.12 (9.46-10.83)

3.90 (3.69-4.12)

  

R

6.30 (5.79-6.87)

11.07 (9.21-13.31)

3.07 (2.55-3.69)

 

Other

n

53

13

13

  

F

2.77 (2.72-2.83)

5.56 (4.65-6.66)

1.46 (1.27-1.67)

  

R

2.68 (2.49-2.87)

6.15 (4.60-8.23)

1.46 (1.27-1.67)

 

Between levels

PB

<0.001

<0.01

<0.001

Any proxy use

Nog

n

227

76

79

  

F

6.87 (6.72-7.03)

8.95 (8.37-9.56)

3.41 (3.23-3.61)

  

R

5.51 (5.02-6.04)

9.64 (7.99-11.64)

2.63 (2.15-3.20)

 

Yes

n

101

26

28

  

F

3.15 (3.09-3.20)

14.65 (12.30-17.46)

3.56 (3.13-4.04)

  

R

5.39 (4.84-6.02)

13.82 (10.45-18.27)

3.61 (2.73-4.76)

 

Between levels

PB

NS

<0.05

<0.1

Full histological confirmation

No

n

245

59

59

  

F

3.86 (3.80-3.92)

7.21 (6.57-7.90)

2.43 (2.24-2.63)

  

R

5.25 (4.80-5.74)

9.39 (7.54-11.68)

2.56 (2.09-3.15)

 

Yes

n

83

43

48

  

F

7.67 (7.38-7.98)

11.97 (11.01-13.02)

4.37 (4.09-4.66)

  

R

6.30 (5.47-7.25)

12.32 (9.78-15.52)

3.22 (2.53-4.10)

 

Between levels

PB

<0.05

<0.1

NS

Number of casesh

100-249

n

115

22

27

  

F

3.74 (3.51-3.99)

6.02 (4.86-7.45)

1.93 (1.67-2.24)

  

R

4.43 (3.86-5.09)

8.39 (5.91-11.92)

2.31 (1.71-3.12)

 

250-499

n

86

31

31

  

F

4.85 (4.59-5.12)

8.89 (7.51-10.52)

2.37 (2.10-2.68)

  

R

5.75 (4.95-6.69)

10.17 (7.81-13.22)

2.37 (1.81-3.09)

 

500-999

n

64

18

18

  

F

4.93 (4.68-5.19)

8.26 (6.92-9.85)

2.40 (2.07-2.77)

  

R

6.17 (5.25-7.25)

11.35 (7.79-16.53)

2.86 (2.08-3.92)

 

1000+

n

63

31

31

  

F

4.15 (4.08-4.21)

10.51 (9.74-11.35)

4.61 (4.32-4.92)

  

R

6.14 (5.15-7.32)

10.88 (8.16-14.51)

3.77 (2.82-5.02)

 

Between levels

PB

<0.01

NS

<0.1

Smoking product

Any

n

205

54

55

  

F

3.79 (3.73-3.85)

6.86 (6.16-7.65)

2.42 (2.20-2.66)

  

R

5.41 (4.90-5.97

8.94 (7.02-11.39)

2.27 (1.87-2.76)

 

Cigarettes (ignoring

n

114

46

50

 

other products)

F

6.52 (6.31-6.73)

10.99 (10.18-11.85)

3.94 (3.71-4.19)

  

R

5.54 (4.87-6.30)

11.86 (9.57-14.71)

3.46 (2.70-4.44)

 

Cigarettes only

n

9

2

2

  

F

8.11 (7.11-9.26)

38.79 (18.74-80.31)

4.26 (3.15-5.74)

  

R

6.83 (4.63-10.08)

38.79 (18.74-80.31)

4.26 (3.15-5.74)

 

Between levels

PB

NS

<0.001

<0.001

Unexposed base

Never any product

n

236

64

67

  

F

3.84 (3.78-3.90)

8.06 (7.37-8.82)

2.57 (2.38-2.77)

  

R

5.31 (4.84-5.81)

9.68 (7.81-12.01)

2.46 (2.09-2.89)

 

Never cigarettes

n

92

38

40

  

F

7.01 (6.77-7.26)

11.04 (10.13-12.02)

4.30 (4.02-4.60)

  

R

5.96 (5.17-6.88)

11.92 (9.24-15.38)

3.56 (2.66-4.78)

 

Between levels

PB

NS

NS

<0.05

Number of adjustment factors

0

n

164

53

54

  

F

7.12 (6.92-7.33)

7.93 (7.20-8.74)

2.40 (2.21-2.60)

  

R

5.44 (4.86-6.09)

9.86 (7.79-12.49)

2.61 (2.11-3.23)

 

1

n

69

18

20

  

F

5.13 (4.90-5.37)

12.59 (10.37-15.30)

3.24 (2.81-3.73)

  

R

5.48 (4.72-6.37)

11.34 (7.36-17.47)

2.66 (1.74-4.06)

 

2+

n

95

31

33

  

F

3.40 (3.34-3.46)

10.48 (9.59-11.45)

4.61 (4.29-4.95)

  

R

5.56 (4.87-6.34)

11.02 (8.35-14.54)

3.30 (2.50-4.36)

 

Between levels

PB

NS

NS

NS

  1. a Within each study, results for ever smokers are selected in the following preference order, within each sex, for:
  2. smoking product – any, cigarettes (ignoring other products), cigarettes only;
  3. cigarette type – any, manufactured (with or without handrolled), manufactured only;
  4. unexposed group – never any product, never cigarettes, near equivalent (see Methods);
  5. follow-up period – longest available;
  6. lung cancer type – see notes c to e;
  7. race – all or nearest available, otherwise by race;
  8. overlapping studies – principal, subsidiary;
  9. age – whole study, widest available age group.
  10. Results are then selected for:
  11. sex – single sex results, combined sex results;
  12. adjustment for potential confounders – most available.
  13. b n = number of estimates combined, F = fixed-effect meta-analysis RR (95% CI), R = random-effects meta-analysis RR (95% CI), H = heterogeneity chisquared per degree of freedom, PH = probability value for heterogeneity expressed as p < 0.001, p < 0.01, p < 0.05, p < 0.1 or NS (p ≥ 0.1), PE = probability value for Egger’s test of publication bias similarly expressed, PB = probability value for between levels (see Methods) similarly expressed.
  14. c All or nearest available, must include at least squamous cell carcinoma and adenocarcinoma.
  15. d Squamous cell carcinoma or nearest available, but not including adenocarcinoma.
  16. e Adenocarcinoma or nearest available, but not including squamous cell carcinoma.
  17. f Or nested case–control or case-cohort in the case of 5 estimates for all lung cancer, 4 for squamous and 4 for adeno.
  18. g Or not known in the case of 10 estimates for all lung cancer, 2 for squamous, and 2 for adeno.
  19. h In the study as a whole.