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Table 11 Main meta-analyses for current or ever smoking of any product (or cigarettes, if not available) a

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

Preference Statisticb All lung cancerc Squamousd Adenoe
Ever smoking to current smoking n 342 110 116
  F 4.25 (4.20-4.31) 9.15 (8.63-9.70) 3.38 (3.23-3.55)
  R 5.48 (5.07-5.93) 10.58 (9.04-12.37) 2.94 (2.52-3.43)
  H, PH 22.46, p < 0.001 5.22, p < 0.001 8.61, p < 0.001
Current smoking to ever smoking n 344 110 116
  F 4.45 (4.39-4.51) 10.08 (9.51-10.69) 3.58 (3.41-3.76)
  R 6.20 (5.68-6.77) 11.53 (9.73-13.66) 3.13 (2.67-3.67)
  H, PH 28.33, p < 0.001 6.30, p < 0.001 8.99, p < 0.001
  1. a Within each study, results are selected in the following preference order, within each sex, for:
  2. smoking status – ever, current or current, ever according to analysis;
  3. smoking product – any, cigarettes (ignoring other products), cigarettes only;
  4. cigarette type – any, manufactured (with or without handrolled), manufactured only;
  5. unexposed group – never any product, never cigarettes, near equivalent (see Methods);
  6. follow-up period – longest available;
  7. lung cancer type – see notes c to e;
  8. race – all or nearest available, otherwise by race;
  9. overlapping studies – principal, subsidiary;
  10. age – whole study, widest available age group.
  11. Results are then selected for:
  12. sex – single sex results, combined sex results;
  13. adjustment for potential confounders – most available.
  14. 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.
  15. c All or nearest available, must include at least squamous cell carcinoma and adenocarcinoma.
  16. d Squamous cell carcinoma or nearest available, but not including adenocarcinoma.
  17. e Adenocarcinoma or nearest available, but not including squamous cell carcinoma.