Smoking Cessation and Lung Function in Mild-to-Moderate Chronic Obstructive Pulmonary Disease

TLDR

Long‑term benefits of smoking cessation on lung function and predictive factors such as airway hyperresponsiveness remain inadequately quantified. A 5‑year prospective randomized trial at 10 North American centers enrolled 3,926 smokers with mild‑to‑moderate COPD, randomizing them to two cessation interventions or no intervention and measuring annual lung function. Quitters gained an average 47 ml (2 %) FEV1 in the first year, and their subsequent decline was half that of continuing smokers, with predictors including β‑agonist responsiveness, baseline FEV1, methacholine reactivity, age, sex, race, and smoking rate; respiratory symptoms did not predict changes, and benefits applied even to heavy smokers, older adults, or those with poor baseline function. The study was conducted by the Lung Health Study Research Group and published as “Smoking cessation and lung function in mild‑to‑moderate chronic obstructive pulmonary disease.”.

Abstract

Previous studies of lung function in relation to smoking cessation have not adequately quantified the long-term benefit of smoking cessation, nor established the predictive value of characteristics such as airway hyperresponsiveness. In a prospective randomized clinical trial at 10 North American medical centers, we studied 3,926 smokers with mild-to-moderate airway obstruction (3,818 with analyzable results; mean age at entry, 48.5 yr; 36% women) randomized to one of two smoking cessation groups or to a nonintervention group. We measured lung function annually for 5 yr. Participants who stopped smoking experienced an improvement in FEV1 in the year after quitting (an average of 47 ml or 2%). The subsequent rate of decline in FEV1 among sustained quitters was half the rate among continuing smokers, 31 ± 48 versus 62 ± 55 ml (mean ± SD), comparable to that of never-smokers. Predictors of change in lung function included responsiveness to β -agonist, baseline FEV1, methacholine reactivity, age, sex, race, and baseline smoking rate. Respiratory symptoms were not predictive of changes in lung function. Smokers with airflow obstruction benefit from quitting despite previous heavy smoking, advanced age, poor baseline lung function, or airway hyperresponsiveness. Scanlon PD, Connett JE, Waller LA, Altose MD, Bailey WC, Buist AS, Tashkin DP, for the Lung Health Study Research Group. Smoking cessation and lung function in mild-to-moderate chronic obstructive pulmonary disease: The Lung Health Study.