The effect of smoking cessation on airway-occluding mucus plugs in COPD

<bold>Background:</bold> Airway mucus plugs (MP) are frequently found on computed tomography (CT) in patients with COPD and linked with impaired lung function. Our previous study showed resolution of MP is associated with a lesser decline of FEV1 compared to persisting MP. However, which intervenable factors are associated with resolution of MP is unclear. We hypothesized cessation of cigarette smoking may lead to resolution of MP. <bold>Methods:</bold> We evaluated chest CT scans of current and former smokers with COPD from the COPDGene study at the baseline and 5-year follow-up visits. We defined MP as any completely occluded airway in at least one pulmonary segment. Among those with MP at the baseline visit, we defined resolution of MP if no MP was found at follow-up versus persisting MP if MP was found at follow-up. Using propensity score matching, we assessed the effect of smoking cessation between the two visits on resolution of MP after adjusting for age, sex, race, BMI, pack-years, asthma, FEV1%-predicted and emphysema. <bold>Results:</bold> Of 4,363 participants whose baseline CT scans were evaluated for MP, 2,164 had a 5-year follow up CT scan and 2,199 were lost to follow up. Of 784 participants who had MP at the baseline visit, 344 (43.9%) had resolution of MP and 440 (56.1%) had persisting MP at follow-up. Of the 784 participants, 344 (43.9%) were smoking at the baseline visit, and 107 of them (31.1%) quit smoking at follow-up. The propensity-score-adjusted effect of smoking cessation on resolution of MP was an increased absolute chance of resolution of MP by 0.190 [95% CI: (0.072, 0.307)]. <bold>Conclusion:</bold> Cessation of smoking may be an effective intervention for resolution of MP.