Changes in Lung Function (Percentage of Predicted FEV1) in Patients Who Quit Smoking Compared With Those Who Continue

During the first year, lung function improved in patients who quit smoking and declined in those who continued. Subsequently, the rate of decline in those who continued was twice that of those who quit. Function declined in those who relapsed and improved in those who quit regardless of when the change occurred. Based on data from Scanlon PD et al: Smoking cessation and lung function in mild-to-moderate chronic obstructive pulmonary disease; the Lung Health Study. American Journal of Respiratory and Critical Care Medicine 161:381–390, 2000.