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Table 12 Main meta-analyses for ex 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

182

33

34

  

F

5.80 (5.63-5.96)

10.25 (9.34-11.24)

4.38 (4.04-4.73)

  

R

4.30 (3.93-4.71)

8.74 (6.94-11.01)

2.85 (2.20-3.70)

  

H, PH

6.98, <0.001

3.54, <0.001

7.91, <0.001

  

PE

p < 0.001

NS

p < 0.001

Sex

Male

n

100

17

17

  

F

5.15 (4.93-5.37)

9.31 (8.27-10.47)

4.59 (4.10-5.15)

  

R

4.48 (3.98-5.06)

8.41 (6.18-11.45)

3.45 (2.40-4.96)

 

Female

n

62

14

15

  

F

5.81 (5.51-6.14)

11.66 (9.94-13.68)

4.48 (4.00-5.02)

  

R

3.58 (3.00-4.29)

8.03 (5.18-12.45)

2.39 (1.55-3.69)

 

Combined

n

20

2

2

  

F

6.98 (6.61-7.37)

15.23 (9.63-24.08)

1.97 (1.35-2.88)

  

R

5.58 (4.23-7.36)

15.23 (9.63-24.08)

2.07 (0.67-6.38)

 

Between levels

PB

<0.05

<0.1

NS

Location

North America

n

80

18

17

  

F

6.79 (6.57-7.01)

10.83 (9.73-12.05)

5.69 (5.20-6.23)

  

R

5.44 (4.91-6.03)

9.43 (6.84-13.01)

4.08 (3.08-5.39)

 

United Kingdom

n

21

0

0

  

F

4.14 (3.48-4.92)

  
  

R

3.72 (2.51-5.50)

  
 

Scandinavia

n

21

2

2

  

F

2.67 (2.29-3.11)

4.06 (1.61-10.25)

1.48 (0.77-2.83)

  

R

2.62 (2.01-3.42)

4.06 (1.61-10.25)

1.48 (0.77-2.83)

 

Other Europe

n

24

6

6

  

F

3.57 (3.26-3.92)

9.10 (7.38-11.22)

2.27 (1.82-2.84)

  

R

3.96 (3.07-5.12)

8.42 (5.03-14.10)

2.58 (1.47-4.52)

 

China

n

5

0

0

  

F

3.46 (2.70-4.44)

  
  

R

3.09 (2.02-4.74)

  
 

Japan

n

14

6

8

  

F

2.35 (2.01-2.76)

9.32 (5.69-15.28)

1.60 (1.25-2.05)

  

R

2.40 (1.99-2.89)

9.32 (5.69-15.28)

1.60 (1.25-2.05)

 

Other Asia

n

5

0

0

  

F

2.13 (1.37-3.32)

  
  

R

2.12 (1.29-3.47)

  
 

Other or multiregion

n

12

1

1

  

F

5.77 (4.73-7.03)

3.60 (1.00-12.93)

4.80 (1.79-12.85)

  

R

5.84 (4.60-7.41)

3.60 (1.00-12.93)

4.80 (1.79-12.85)

 

Between levels

PB

<0.001

NS

<0.001

Start year of study

Before 1960

n

18

2

1

  

F

3.55 (3.19-3.94)

1.34 (0.71-2.52)

1.42 (0.29-6.82)

  

R

3.81 (2.84-5.11)

1.34 (0.71-2.52)

1.42 (0.29-6.82)

 

1960-69

n

36

5

5

  

F

4.06 (3.68-4.48)

11.29 (8.77-14.54)

3.56 (2.95-4.29)

  

R

3.32 (2.71-4.08)

11.29 (8.77-14.54)

2.80 (1.86-4.21)

 

1970-79

n

36

8

10

  

F

3.81 (3.50-4.14)

9.85 (8.08-12.02)

2.38 (1.95-2.91)

  

R

3.48 (2.85-4.25)

9.39 (6.00-14.68)

2.59 (1.75-3.84)

 

1980-89

n

70

16

16

  

F

6.91 (6.68-7.15)

10.97 (9.75-12.36)

5.67 (5.13-6.26)

  

R

5.22 (4.65-5.86)

10.35 (7.57-14.15)

3.37 (2.35-4.85)

 

1990 or later

n

22

2

2

  

F

4.73 (4.11-5.43)

8.38 (3.79-18.53)

1.58 (1.00-2.49)

  

R

5.17 (3.66-7.31)

7.58 (1.98-29.00)

2.22 (0.56-8.79)

 

Between levels

PB

<0.001

<0.001

NS

Study type

Case–control

n

123

28

30

  

F

6.28 (6.09-6.48)

10.71 (9.74-11.76)

4.44 (4.10-4.81)

  

R

4.88 (4.41-5.41)

9.94 (8.05-12.28)

2.96 (2.26-3.87)

 

Prospectivef

n

59

5

4

  

F

3.84 (3.58-4.12)

2.34 (1.35-4.03)

1.87 (1.04-3.36)

  

R

3.18 (2.70-3.74)

3.54 (1.38-9.09)

1.87 (1.04-3.36)

 

Between levels

PB

<0.001

<0.05

NS

National cigarette tobacco type

Virginia

n

30

2

2

  

F

3.95 (3.45-4.53)

9.22 (4.21-20.18)

2.03 (1.15-3.57)

  

R

3.79 (2.85-5.04)

9.22 (4.21-20.18)

2.27 (0.92-5.59)

 

Blended

n

147

31

32

  

F

5.94 (5.77-6.12)

10.26 (9.35-11.27)

4.44 (4.10-4.81)

  

R

4.45 (4.04-4.91)

8.68 (6.83-11.04)

2.89 (2.22-3.77)

 

Other

n

5

0

0

  

F

3.46 (2.70-4.44)

  
  

R

3.09 (2.02-4.74)

  
 

Between levels

PB

NS

NS

NS

Any proxy use

Nog

n

141

27

28

  

F

6.02 (5.84-6.21)

10.17 (9.23-11.20)

4.46 (4.11-4.84)

  

R

4.12 (3.70-4.59)

8.33 (6.38-10.89)

2.73 (2.04-3.65)

 

Yes

n

41

6

6

  

F

4.60 (4.26-4.96)

11.24 (8.01-15.78)

3.30 (2.42-4.52)

  

R

4.79 (4.20-5.47)

11.24 (8.01-15.78)

3.39 (2.25-5.11)

 

Between levels

PB

<0.1

NS

NS

Full histological confirmation

No

n

131

16

15

  

F

5.73 (5.53-5.93)

8.91 (7.03-11.30)

3.50 (2.89-4.23)

  

R

4.11 (3.68-4.60)

8.11 (5.05-13.01)

3.24 (2.13-4.94)

 

Yes

n

51

17

19

  

F

5.93 (5.65-6.23)

10.51 (9.50-11.62)

4.59 (4.21-5.00)

  

R

4.76 (4.02-5.63)

9.28 (7.08-12.15)

2.60 (1.85-3.65)

 

Between levels

PB

NS

NS

NS

Number of casesg

100-249

n

51

7

9

  

F

3.18 (2.79-3.64)

4.03 (2.17-7.49)

1.95 (1.40-2.70)

  

R

3.36 (2.65-4.25)

4.03 (2.17-7.49)

1.95 (1.40-2.70)

 

250-499

n

45

9

8

  

F

4.21 (3.80-4.66)

4.59 (3.17-6.65)

1.86 (1.36-2.54)

  

R

4.13 (3.42-4.99)

5.48 (2.84-10.58)

2.10 (1.21-3.64)

 

500-999

n

37

4

4

  

F

4.61 (4.21-5.04)

9.58 (5.65-16.25)

3.23 (2.13-4.90)

  

R

4.86 (4.07-5.80)

9.58 (5.65-16.25)

3.58 (1.79-7.13)

 

1000+

n

49

13

13

  

F

6.39 (6.19-6.60)

11.13 (10.08-12.28)

5.00 (4.59-5.45)

  

R

4.76 (4.13-5.48)

11.53 (8.87-14.99)

3.69 (2.60-5.22)

 

Between levels

PB

<0.05

<0.01

<0.05

Smoking product

Any

n

81

9

9

  

F

4.76 (4.51-5.02)

8.13 (5.16-12.79)

1.60 (1.21-2.12)

  

R

4.09 (3.53-4.74)

8.13 (5.16-12.79)

1.68 (1.17-2.40)

 

Cigarettes (ignoring

n

90

23

25

 

other products)

F

6.38 (6.16-6.60)

10.75 (9.77-11.83)

4.77 (4.40-5.18)

  

R

4.49 (3.98-5.06)

9.99 (7.93-12.58)

3.35 (2.54-4.41)

 

Cigarettes only

n

11

1

0

  

F

4.96 (4.36-5.64)

1.23 (0.60-2.52)

 
  

R

4.18 (2.63-6.66)

1.23 (0.60-2.52)

 
 

Between levels

PB

NS

<0.001

<0.01

Unexposed base

Never any product

n

121

17

18

  

F

5.64 (5.44-5.85)

8.41 (7.12-9.94)

2.38 (2.06-2.76)

  

R

4.35 (3.89-4.88)

6.63 (4.39-10.02)

2.17 (1.61-2.94)

 

Never cigarettes

n

61

16

16

  

F

6.08 (5.80-6.37)

11.19 (10.00-12.51)

5.60 (5.10-6.15)

  

R

4.18 (3.56-4.91)

11.13 (8.48-14.60)

3.83 (2.78-5.27)

 

Between levels

PB

NS

<0.05

<0.05

Number of adjustment factors

0

n

86

16

16

  

F

6.10 (5.87-6.34)

9.81 (8.41-11.45)

2.82 (2.47-3.22)

  

R

4.84 (4.26-5.50)

9.11 (6.95-11.94)

2.61 (1.91-3.58)

 

1

n

48

10

9

  

F

4.40 (4.11-4.71)

7.03 (5.21-9.47)

2.13 (1.66-2.73)

  

R

3.96 (3.37-4.65)

6.43 (3.31-12.47)

2.17 (1.56-3.03)

 

2+

n

48

7

9

  

F

6.23 (5.91-6.58)

11.28 (9.94-12.80)

6.64 (5.97-7.39)

  

R

3.81 (3.11-4.66)

11.09 (6.78-18.13)

4.42 (3.05-6.40)

 

Between levels

PB

<0.1

NS

<0.05

  1. a Within each study, results for ex 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 adenocarcinoma.
  18. g In the study as a whole.
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