Mucus Plugs in COPD: Prevalence, Exacerbations, Mortality Risk

CT-detected mucus plugs are common in moderate to severe COPD and are linked to worse lung function, future exacerbations, and higher all-cause mortality, according to Emily Wan, MD, MPH, who presented a session on the topic at the GOLD 2026 COPD International Conference.¹

Wan, of VA Boston Healthcare System and Brigham and Women’s Hospital, framed mucus plugging as a finding of stable disease rather than an artifact of acute illness. She illustrated the point with a 77-year-old current smoker with moderate COPD and no respiratory symptoms, whose routine lung cancer screening CT revealed occlusive plugs in both lower lobes.

“We are not talking about mucus plugs during acute illness. We’re talking about mucus plugs when people are actually in their usual state of health,” said Wan during this session.

Plugging in COPD is not a new observation. Bronchographic and histologic work by James Hogg in 1968 attributed increased airway resistance partly to mucus plugs, but systematic imaging research is far more recent. “This concerted effort to characterize and quantify mucus plugs has really taken flight over the last decade,” said Wan.

How Common Are Mucus Plugs in COPD?

Across multicenter research cohorts, the prevalence of any mucus plug ranged from 31% to 67%, a spread Wan attributed to heterogeneity in both populations and assessment methods.¹ Most studies rely on visual scoring by expert readers, and criteria for occlusion, distal airway patency, and exclusion of the lung periphery still vary. Interrater agreement within individual studies is high, however.

The most widely used metric, the mucus plug score, assigns 1 point to each bronchopulmonary segment containing a plug. Both prevalence and plug burden rose with worsening GOLD spirometry grade, and higher scores tracked with lower FEV1, FEV1/FVC ratio, and FEF25-75 and with greater airway wall thickness.

Bronchiectasis prevalence ranged from 18% to 28% among patients without plugs and reached 50% among those with plugs. Associations with quantitative emphysema were inconsistent between North American and Asian cohorts.

Do Mucus Plugs Matter Without Cough or Phlegm?

Plugs were consistently linked to more dyspnea, worse COPD control, and poorer quality of life, but their relationship with chronic bronchitis was less robust. In a cohort of patients with chronic bronchitis undergoing bronchial rheoplasty, only 55% had mucus plugs.

“Chronic bronchitis is not synonymous with mucus plugging. While we do see an enrichment of subjects reporting chronic bronchitis who have mucus plugs, it’s by no means universal,” said Wan.

Silent plugs, or plugs without cough or phlegm, appeared in about 35% of patients in 1 cohort. These patients had worse exercise tolerance, lower lung function, poorer quality of life, and more prior exacerbations than peers without plugs. “Silent mucus plugs do appear to matter,” said Wan.

What Outcomes Are Linked to Mucus Plugs in COPD?

Across cohorts with 2 to 8 years of follow-up, mucus plugs predicted future moderate to severe and severe exacerbations, and each 1-point increase in mucus plug score corresponded to a 3% to 8% higher risk.¹ Plugs were also associated with all-cause mortality, first in COPDGene and later in 2 independent cohorts.²

In 1 study, a high score was tied to respiratory and cancer mortality but not cardiovascular mortality. A single-center Asian cohort also found higher lung cancer incidence, driven by squamous cell carcinoma, among patients with plugs, though Wan noted the cancer data remain limited.

Longitudinal CT data showed a recurrence rate of about 70%, yet many COPDGene participants changed status over 5 years. Those with resolved or persistently absent plugs lost less lung function than those with new or persistent plugs.

“In a subset of individuals, mucus plugs are dynamic, which is exciting, right? This is potentially changeable,” said Wan.

Editor's Note: This summary has been edited for grammar and clarity using artificial intelligence tools.

References

1. Wan E. Burden of mucus plugging in patients with moderate to severe COPD. Presented at: GOLD 2026 COPD International Conference; November 5, 2026; Philadelphia, PA.

2. Diaz AA, Orejas JL, Grumley S, et al. Airway-occluding mucus plugs and mortality in patients with chronic obstructive pulmonary disease. JAMA. 2023;329(21):1832-1839. doi:10.1001/jama.2023.2065.