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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.
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