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Table 8 Main meta-analyses for current 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

195

41

44

  

F

9.29 (9.07-9.52)

13.77 (12.75-14.87)

4.77 (4.49-5.07)

  

R

8.43 (7.63-9.31)

16.91 (13.14-21.76)

4.21 (3.32-5.34)

  

H, PH

13.76, p < 0.001

7.22, p < 0.001

12.28, p < 0.001

  

PE

p < 0.05

NS

NS

Sex

Male

n

108

22

22

  

F

8.68 (8.36-9.02)

13.11 (11.85-14.51)

5.54 (5.04-6.09)

  

R

9.16 (8.00-10.49)

17.73 (12.78-24.59)

5.56 (4.06-7.61)

 

Female

n

68

17

20

  

F

8.06 (7.75-8.38)

13.44 (11.86-15.23)

4.40 (4.05-7.79)

  

R

6.76 (5.65-8.08)

14.77 (9.42-23.17)

3.20 (2.18-4.71)

 

Combined

n

19

2

2

  

F

13.19 (12.55-13.86)

34.23 (23.43-50.00)

3.11 (2.35-4.11)

  

R

12.09 (9.38-15.60)

34.23 (23.43-50.00)

3.57 (1.06-12.07)

 

Between levels

PB

<0.001

<0.01

<0.1

Location

North America

n

84

24

24

  

F

12.45 (12.09-12.82)

17.99 (16.29-19.85)

7.63 (7.05-8.25)

  

R

11.68 (10.61-12.85)

20.95 (15.41-28.48)

6.72 (5.50-8.21)

 

United Kingdom

n

25

0

0

  

F

6.90 (6.10-7.81)

  
  

R

7.53 (5.40-10.50)

  
 

Scandinavia

n

21

2

2

  

F

8.16 (7.30-9.12)

15.51 (6.63-36.28)

4.66 (2.67-8.13)

  

R

8.68 (7.14-10.54)

15.51 (6.63-36.28)

4.69 (2.62-8.40)

 

Other Europe

n

23

6

6

  

F

5.88 (5.43-6.38)

12.22 (10.16-14.69)

2.65 (2.20-3.18)

  

R

8.65 (5.98-12.51)

13.66 (7.38-25.30)

3.30 (1.93-5.65)

 

China

n

5

0

0

  

F

3.07 (2.56-3.68)

  
  

R

2.94 (2.23-3.88)

  
 

Japan

n

18

8

11

  

F

3.68 (3.43-3.95)

6.85 (5.77-8.13)

2.11 (1.87-2.37)

  

R

3.55 (3.05-4.14)

11.25 (6.89-18.35)

1.87 (1.42-2.47)

 

Other Asia

n

7

0

0

  

F

2.91 (2.26-3.76)

  
  

R

2.90 (2.04-4.13)

  
 

Other or multiregion

n

12

1

1

  

F

7.09 (6.10-8.24)

10.40 (3.31-32.66)

7.90 (2.99-20.85)

  

R

9.88 (6.89-14.17)

10.40 (3.31-32.66)

7.90 (2.99-20.85)

 

Between levels

PB

<0.001

NS

<0.001

Start year of study

Before 1960

n

22

6

5

  

F

6.13 (5.70-6.59)

6.87 (4.93-9.08)

3.35 (2.43-4.62)

  

R

6.39 (4.70-8.69)

11.05 (4.07-30.00)

2.92 (1.17-7.28)

 

1960-69

n

40

7

7

  

F

5.43 (5.12-5.75)

10.55 (9.07-12.26)

4.22 (3.76-4.74)

  

R

6.44 (5.21-7.95)

15.48 (7.08-33.83)

4.55 (2.50-8.30)

 

1970-79

n

41

8

11

  

F

7.27 (6.79-7.79)

14.53 (12.21-17.29)

2.99 (2.55-3.50)

  

R

7.34 (5.94-9.06)

16.43 (8.67-31.14)

3.41 (2.10-5.53)

 

1980-89

n

70

18

19

  

F

12.35 (11.97-12.75)

16.70 (14.93-18.67)

6.38 (5.84-6.96)

  

R

10.18 (9.02-11.49)

19.69 (15.08-25.71)

5.06 (3.65-7.02)

 

1990 or later

n

22

2

2

  

F

10.32 (9.10-11.70)

20.79 (10.16-42.55)

2.28 (1.63-3.19)

  

R

12.81 (8.70-18.85)

19.39 (6.38-58.88)

3.62 (0.92-14.29)

 

Between levels

PB

<0.001

NS

NS

Study type

Case–control

n

128

30

34

  

F

9.69 (9.43-9.95)

13.59 (12.56-14.70)

4.71 (4.42-5.01)

  

R

8.56 (7.58-9.68)

16.21 (12.23-21.50)

3.88 (2.96-5.07)

 

Prospectivef

n

67

11

10

  

F

8.04 (7.65-8.46)

18.87 (12.90-27.59)

5.93 (4.59-7.66)

  

R

8.15 (6.87-9.67)

19.63 (12.21-31.56)

5.95 (4.07-8.69)

 

Between levels

PB

NS

NS

p < 0.1

National cigarette tobacco type

Virginia

n

34

2

2

  

F

6.75 (6.12-7.44)

31.44 (15.03-65.78)

6.93 (4.35-11.07)

  

R

8.01 (6.16-10.41)

31.44 (15.03-65.78)

6.93 (4.35-11.07)

 

Blended

n

154

39

42

  

F

9.70 (9.46-9.95)

13.65 (12.63-14.75)

4.74 (4.45-5.04)

  

R

8.92 (8.01-9.94)

16.41 (12.68-21.24)

4.10 (3.21-5.23)

 

Other

n

7

0

0

  

F

3.13 (2.64-3.72)

  
  

R

3.09 (2.50-3.83)

  
 

Between levels

PB

<0.001

NS

p < 0.1

Any proxy use

Nog

n

156

35

38

  

F

9.24 (9.00-9.48)

13.09 (12.09-14.18)

4.67 (4.39-4.98)

  

R

8.04 (7.17-9.01)

15.78 (12.00-20.74)

3.88 (2.99-5.03)

 

Yes

n

39

6

6

  

F

9.68 (9.05-10.36)

27.96 (20.74-37.69)

6.88 (5.27-8.97)

  

R

10.03 (8.32-12.09)

27.96 (20.74-37.69)

6.88 (5.27-8.97)

 

Between levels

PB

<0.05

<0.01

p < 0.01

Full histological confirmation

No

n

144

24

23

  

F

8.87 (8.62-9.12)

11.53 (10.05-13.23)

3.99 (3.59-4.43)

  

R

7.91 (7.00-8.93)

19.20 (12.62-29.22)

5.59 (3.98-7.84)

 

Yes

n

51

17

21

  

F

10.45 (9.99-10.92)

14.94 (13.61-16.40)

5.25 (4.87-5.67)

  

R

10.08 (8.46-12.01)

14.77 (10.61-20.57)

3.20 (2.28-4.49)

 

Between levels

PB

<0.05

NS

p < 0.05

Number of casesh

100-249

n

56

8

11

  

F

5.50 (4.96-6.11)

5.62 (3.96-7.98)

2.54 (2.02-3.19)

  

R

6.90 (5.46-8.72)

11.28 (5.08-25.04)

2.45 (1.54-3.90)

 

250-499

n

48

9

9

  

F

8.47 (7.79-9.22)

16.67 (11.49-24.18)

3.20 (2.59-3.95)

  

R

8.60 (7.02-10.52)

17.09 (11.28-25.91)

3.83 (2.41-6.09)

 

500-999

n

38

4

4

  

F

7.56 (7.04-8.13)

22.44 (13.58-37.07)

7.35 (5.12-10.55)

  

R

9.54 (7.65-11.89)

22.44 (13.58-37.07)

7.35 (5.12-10.55)

 

1000+

n

53

20

20

  

F

10.01 (9.74-10.29)

14.15 (13.03-15.35)

5.18 (4.84-5.54)

  

R

9.03 (7.63-10.69)

17.87 (12.92-24.70)

4.97 (3.54-6.97)

 

Between levels

PB

NS

NS

p <0.01

Smoking product

Any

n

85

9

11

  

F

8.00 (7.64-8.37)

17.58 (11.99-25.77)

2.61 (2.16-3.14)

  

R

7.57 (6.47-8.84)

17.76 (11.75-26.86)

2.40 (1.59-3.61)

 

Cigarettes (ignoring

n

95

26

28

 

other products)

F

9.84 (9.56-10.14)

13.51 (12.47-14.64)

5.11 (4.79-5.46)

  

R

8.95 (7.76-10.33)

16.43 (12.08-22.33)

5.02 (3.76-6.70)

 

Cigarettes only

n

15

6

5

  

F

9.77 (8.92-10.69)

17.80 (11.39-27.83)

5.69 (4.00-8.09)

  

R

10.51 (7.70-14.34)

18.04 (9.79-33.27)

5.56 (2.61-11.85)

 

Between levels

PB

NS

NS

p < 0.05

Unexposed base

Never any product

n

134

24

27

  

F

8.80 (8.55-9.06)

9.80 (8.75-10.98)

3.01 (2.75-3.29)

  

R

8.24 (7.28-9.34)

14.05 (9.75-20.23)

3.10 (2.37-4.07)

 

Never cigarettes

n

61

17

17

  

F

10.43 (10.00-10.88)

18.44 (16.60-20.48)

7.17 (6.59-7.80)

  

R

8.89 (7.52-10.51)

21.71 (16.38-28.76)

6.61 (4.89-8.95)

 

Between levels

PB

NS

<0.1

<0.001

Number of adjustment variables

0

n

86

16

17

  

F

10.84 (10.46-11.23)

14.93 (13.02-17.12)

4.28 (3.83-4.79)

  

R

9.40 (8.02-11.03)

17.15 (10.78-27.27)

3.90 (2.54-6.00)

 

1

n

62

15

14

  

F

7.80 (7.43-8.19)

19.11 (15.33-23.83)

3.25 (2.76-3.83)

  

R

7.28 (6.14-8.63)

18.27 (12.55-26.60)

3.46 (2.27-5.29)

 

2+

n

47

10

13

  

F

8.49 (8.13-8.87)

12.24 (11.04-13.57)

5.58 (5.13-6.05)

  

R

8.54 (7.02-10.39)

15.20 (9.40-24.58)

5.68 (3.80-8.49)

 

Between levels

PB

p < 0.1

NS

NS

  1. a Within each study, results for current 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 < 0.05, 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, 3 for squamous and 3 for adeno.
  18. g Including not known.
  19. h In the study as a whole.