Objectives: To estimate the gender-specific risk of mortality from cardiovascular disease according to smoking status and time since smoking cessation among former smokers in Japan.
Design: Prospective study.
Setting: 140,026 males and 156,810 females aged 40-79 years who participated in one of three cohort studies conducted in Japan between 1980 and 1990.
Outcome: The gender-specific hazard ratios (HRs) for cardiovascular disease mortality were calculated after adjustment for age and cohort.
Results: The age-adjusted and cohort-adjusted HRs for current smokers compared with lifelong non-smokers were 1.51 (95% CI 1.38 to 1.64) for total cardiovascular diseases, 2.19 (95% CI 1.79 to 2.67) for coronary heart disease and 1.24 (95% CI 1.10 to 1.41) for total stroke in males, and were 1.85 (95% CI 1.65 to 2.06), 2.84 (95% CI 2.24 to 3.60) and 1.70 (95% CI 1.44 to 2.01), respectively, in females. The age-adjusted and cohort-adjusted HRs for former smokers compared with current smokers according to the time period since smoking cessation decreased by approximately 5 years after smoking cessation and reached the same level as lifelong non-smokers approximately 10 years after smoking cessation among both males and females.
Conclusions: The present study confirmed the association between smoking and mortality from cardiovascular disease in both males and females. Smoking cessation is a crucial preventive measure against death from cardiovascular disease.