Effect of smoking on FEV decline in a cross-sectional and longitudinal study of a large cohort of Japanese males

The effects of cigarette smoking and smoking cessation on age-related pulmonary function decline was assessed in both cross-sectional and longitudinal studies. In the cross-sectional study, pulmonary function data from 11,875 healthy asymptomatic males, aged between 35 and 74, were analysed and correlated with their smoking history and age. In the longitudinal study, changes in pulmonary function were monitored over a 5-year period in 1888 healthy males. The cross-sectional study showed that the difference in FEV(1) between male never smokers and current smokers was small at a younger age but increased with age. A beneficial effect on FEV(1) decline was observed in those who ceased smoking, even within the previous 12 months. Longitudinally, current smokers showed a more rapid decline in FEV(1) over the 5-year period than non-smokers. Those who ceased smoking had lower rates of decline in FEV(1) than those who continued to smoke. These results indicate that cigarette smoking is associated with a reduction in pulmonary function, and that smoking cessation has a beneficial effect on FEV(1) decline. Provision of a smoking cessation program for all smokers, especially those showing a rapid decline of FEV(1), should be considered as an important strategy to prevent progression of COPD.