Airway Mucus Plugs on Chest Computed Tomography Are Associated with Exacerbations in COPD

Abstract

Rationale/Objective: Acute exacerbations (AEs) of chronic obstructive pulmonary disease (COPD) are associated with significant morbidity and mortality. Whether mucus plugs are associated with prospective exacerbations has not been examined extensively.

Methods: Mucus plugs were visually-identified on baseline chest computed tomography (CT) scans from smokers with Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 2-4 COPD enrolled in two multicenter cohort studies: Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) and COPDGene. Associations between ordinal mucus plug score categories (0/1-2/≥3) and prospectively-ascertained AEs, defined as worsening respiratory symptoms requiring systemic steroids and/or antibiotics (moderate-to-severe) and/or ER/hospitalization (severe), were assessed using multivariable-adjusted zero-inflated Poisson regression; subjects were exacerbation-free at enrollment.

Results: Among 3,250 participants in COPDGene (mean±SD age 63.7±8.4 years, FEV1 50.6%±17.8% predicted, 45.1% female) and 1,716 participants in ECLIPSE (age 63.3±7.1 years, FEV1 48.3%±15.8% predicted, 36.2% female), 44.4% and 46.0% had mucus plugs, respectively. The incidence rates of AEs were 61.0 (COPDGene) and 125.7 (ECLIPSE) per 100 person-years. Relative to those without mucus plugs, the presence of 1-2 and ≥3 mucus plugs was associated with increased risk (adjusted rate ratio, aRR [95%CI]=1.07[1.05-1.09] and 1.15[1.1-1.2] in COPDGene; aRR=1.06[1.02-1.09] and 1.12[1.04-1.2] in ECLIPSE, respectively) for prospective moderate-to-severe AEs. The presence of 1-2 and ≥3 mucus plugs was also associated with increased risk for severe AEs during follow-up (aRR=1.05[1.01-1.08] and 1.09[1.02-1.18] in COPDGene; aRR=1.17[1.07-1.27] and 1.37[1.15-1.62] in ECLIPSE, respectively).

Conclusion: CT-based mucus plugs are associated with an increased risk for future COPD AEs.

Keywords: COPD; COPD exacerbations; Chest computed tomography; Mucus plugs.