Favorable longitudinal change of lung function in patients with asthma-COPD overlap from a COPD cohort

Abstract

Background: The recognition of asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) as a distinct phenotype of COPD or asthma has increased. Although ACO has worse clinical features than non-ACO COPD, limited information is available on long-term outcomes of lung function decline for ACO and non-ACO COPD. Methods: COPD patients with at least 3years of follow-up were selected from the Korean Obstructive Lung Disease cohort. ACO was defined based on 3 major criteria: 1) airflow limitation in individuals 40years of age and older, 2) ≥10 pack-years of smoking history, and 3) a history of asthma or bronchodilator response of >?400mL in forced expiratory volume in 1s (FEV1) at baselin, and at least 1 minor criterion: 1) history of atopy or allergic rhinitis, 2) two separated bronchodilator responses of ≥12% and 200mL in FEV1, or 3) peripheral blood eosinophils ≥300 cells/μL. Lung function decline was compared using a linear mixed effects model for longitudinal data with random intercept and random slope. Results: Among 239 patients, 47 were diagnosed with ACO (19.7%). During the follow-up period, change in smoking status, use of inhaled corticosteroids (ICS) and long-acting β2-agonists or ICS and at least 2 exacerbations per year were similar between patients with non-ACO COPD and ACO. Over a median follow-up duration of 5.8years, patients with non-ACO COPD experienced a faster annual decline inpre-bronchodilator FEV1 than patients with ACO (-?29.3ml/year vs. -13.9ml/year, P?=?0.042), which was persistent after adjustment for confounders affecting lung function decline. Conclusion: Patients with ACO showed favorable longitudinal changes in lung function compared to COPD patients over a median follow-up of 5.8years.