Pulmonary function, smoking cessation and 30 year mortality in middle agedFinnish men

Background-Although it is well known that impaired pulmonary function is a strong predictor of mortality and that smoking decreases pulmonary function , little is known about the long term effect of smoking cessation on mortal ity at different levels of pulmonary function. We have studied the impact o f smoking cessation on mortality over the entire range of baseline pulmonar y function. Methods-The study subjects consisted of men aged 40-59 at entry who were th e Finnish participants in the Seven Countries Study during 1959-89. Results-In all the participants (n = 1582) impaired forced expiratory volum e in 0.75 seconds (FEV0.75) was significantly associated with increased all cause mortality, When those who gave up smoking during the follow up perio d were compared with continuous smokers (n = 860) all cause mortality was f ound to be decreased among those who quit. The relative adjusted hazard (HR ) was 0.71 (95% confidence interval 0.50 to 1.00). The median survival time in those who stopped smoking compared with those who continued to smoke fr om 1969 onwards was 7.65, 7.59, and 6.30 years longer in the lowest, middle and highest tertiles of adjusted FEV0.75 distribution, respectively. In th ose who gave up smoking, mortality from cardiovascular causes was significa ntly lower (HR 0.60 (95% CI 0.37 to 0.98)). Conclusions-These findings suggest that smokers across the entire range of pulmonary function may increase their expectation of lifespan by giving up smoking.