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Smoking cessation and lung function in mild-to-moderate chronic obstructive pulmonary disease. The Lung Health Study.
P D Scanlon1, J E Connett, L A Waller
1Division of Pulmonary and Critical Care Medicine, Mayo Foundation, Rochester, Minnesota 55905, USA. pscanlon@mayo.edu
American Journal of Respiratory and Critical Care Medicine
|February 15, 2000
Summary
Quitting smoking significantly improves lung function (FEV1) and halves its decline rate in smokers with airway obstruction. Benefits persist regardless of smoking history, age, or baseline lung health.
Area of Science:
- Pulmonology
- Respiratory Medicine
- Clinical Trials
Background:
- Long-term benefits of smoking cessation on lung function remain inadequately quantified.
- Predictive value of factors like airway hyperresponsiveness in smoking cessation outcomes is not fully established.
Purpose of the Study:
- To quantify the long-term benefits of smoking cessation on lung function.
- To determine predictors of lung function change following smoking cessation.
Main Methods:
- Prospective randomized clinical trial involving 3,926 smokers with mild-to-moderate airway obstruction across 10 North American centers.
- Annual lung function measurements (FEV1) over 5 years for intervention and non-intervention groups.
- Analysis of predictors including beta-agonist response, baseline FEV1, methacholine reactivity, and demographics.
Main Results:
- Smokers who quit showed an average FEV1 improvement of 47 ml (2%) in the year post-quitting.
- Sustained quitters experienced a halved rate of FEV1 decline (31 ml/yr) compared to continuing smokers (62 ml/yr), similar to never-smokers.
- Baseline FEV1, methacholine reactivity, age, sex, race, and smoking rate predicted lung function changes; respiratory symptoms did not.
Conclusions:
- Smokers with airflow obstruction benefit significantly from quitting, irrespective of prior smoking intensity, age, baseline lung function, or airway hyperresponsiveness.
- Smoking cessation leads to improved FEV1 and a slower rate of lung function decline.
- Specific clinical characteristics predict lung function trajectories in smokers undergoing cessation.