The effects of smoking and smoking cessation on mortality from cardiovascular disease among Japanese: pooled analysis of three large-scale cohort studies in Japan.

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.