Women who smoke like men die like men who smoke: findings from two Australian cohort studies

Background There is controversy about whether men and women with similar smoking histories have similar incidence and mortality rates from smoking related diseases. Objective To compare mortality rates from all causes of death and various smoking related causes for men and women smokers categorised by numbers of cigarettes smoked and for ex-smokers by time since quitting. Methods This was a 10-year follow-up study with deaths identified from the National Death Index. The setting was two cohort studies in Australia established in 1996. Participants were: men (n=12 154) and women (n=11 707) aged (mean (SD)) 72.1 (4.4) and 72.5 (1.5) years, respectively, when recruited. The main outcome measure was HRs for men and women separately and RRs calculated from combined analyses using proportional hazards models (for deaths from all causes) and competing risks proportional hazards models (for specific causes). Results HRs for deaths from all causes for men (n=3549 deaths) and women (n=2665 deaths) among smokers increased with amount smoked and for ex-smokers decreased with time since quitting. Similar effects were found for various groups of smoking-related conditions with the dose-response effects largest for lung cancer and chronic obstructive pulmonary disease. The ratios of HRs for women relative to men were near unity and the 95% CIs included unity for almost all comparisons. Conclusions The data provide strong evidence that men and women with similar patterns of smoking experience similar rates of death due to smoking.