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Table 13 Meta-analyses for smoking of cigarettes, cigars and pipes (all lung cancer) a

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

Product smoked

Statisticb

Ever smoking

Current smoking

Ex smoking

Cigarettes only

n

53c

35c

21

 

F

4.37 (4.27-4.47)

9.32 (8.87-9.80)

4.36 (4.05-4.69)

 

R

6.36 (5.33-7.59)

9.57 (7.90-11.59)

4.22 (3.29-5.40)

 

H, PH

22.95, p < 0.001

10.91, p < 0.001

7.96, p < 0.001

Pipes/cigars only

n

38

26

7

 

F

3.46 (3.20-3.73)

3.74 (3.29-4.26)

2.00 (1.50-2.65)

 

R

2.92 (2.38-3.57)

4.76 (3.44-6.59)

2.00 (1.50-2.65)

 

H, PH

3.60, p < 0.001

4.18, p < 0.001

0.46, NS

Pipes only

n

23

12

5

 

F

3.36 (2.95-3.81)

5.28 (4.55-6.13)

3.32 (2.42-4.55)

 

R

3.31 (2.51-4.35)

5.20 (3.50-7.73)

2.69 (1.53-4.72)

 

H, PH

3.49, p < 0.001

5.43, p < 0.001

2.66, p < 0.05

Cigars only

n

15

15

5

 

F

2.73 (2.32-3.21)

4.05 (3.61-4.54)

3.27 (2.36-4.52)

 

R

2.95 (1.91-4.56)

4.67 (3.49-6.25)

2.85 (1.45-5.61)

 

H, PH

5.68, p < 0.001

4.27, p < 0.001

4.11, p < 0.01

Mixed

n

27

9

7

 

F

7.87 (7.22-8.59)

9.63 (8.46-10.96)

4.79 (4.10-5.60)

 

R

7.37 (5.97-9.11)

9.60 (8.37-11.00)

5.51 (3.88-7.82)

 

H, PH

4.09, p < 0.001

1.05, NS

3.72, p < 0.01

  1. a Within each study, results for the relevant smoking product and smoking status are selected in the following preference order, within each sex, for:
  2. unexposed group – never any product, near equivalent (see Methods);
  3. follow-up period – longest available;
  4. lung cancer type – all or nearest available, must include at least squamous cell carcinoma and adenocarcinoma;
  5. race – all or nearest available, otherwise by race;
  6. overlapping studies – principal, subsidiary;
  7. age – whole study, widest available age group;
  8. sex – single sex results, combined sex results;
  9. adjustment for potential confounders – most available.
  10. 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), PB = probability value for between levels (see Methods) similarly expressed.
  11. c Results differ from those shown earlier (Tables 6, 9) because RRs with unexposed group “never cigarettes” are excluded here.
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BMC Cancer

ISSN: 1471-2407

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