An airway mucus plug (MP) is a complete obstruction of the lumen of an airway with mucus. The prevalence of MPs is 30-54% in individuals with COPD and the presence of MPs on computed tomography (CT) has been associated with worsened COPD outcomes. Women have different manifestations of COPD, but whether there are sex differences in MPs in individuals with COPD and its associations with differential clinical outcomes are unknown.
We selected patients with COPD from the COPDGene Study and visually assessed MP, emphysema, and airway wall thickness on their baseline CT scans.
We used clinical, spirometry, St George’s Respiratory Questionnaire (SGRQ), exercise capacity, modified Medical Research Council (mMRC) dyspnea scale, and oxygen saturation (SpO2) data. We used multivariable logistic regression to assess the association between sex and MP. Covariates included age, race, pack years, current smoking, airway wall thickness and emphysema. We performed sex-stratified multivariable models including the prior predictors and height for examining associations of MP with FEV1, FEV1/FVC, SGRQ, six-minute walk test (6MWT), mMRC dyspnea score ≥2, and SpO2 ≤ 89%.
Of 2089 patients, 45% were women, median age was 63 years. Women had a higher prevalence (35.5% vs. 29.1%) and odds of MP (Odds Ratio (OR) 1.52, p<.001) than men. In adjusted models, the association between MP and outcomes in women was: FEV1 -80mL (p<.001) , FEV1/FVC -1.7% (p=.006), SGRQ +8.9 points (p<.001), 6MWT -17m (p=.038), mMRC ≥ 2 OR 1.33 (p=.14) and SpO2 ≤ 89% OR 1.33 (p=.28). Estimates for men were: FEV1 -119mL (p<.001), FEV1/FVC -2.9% (p<.001), SGRQ +8.0 points (p.<001), 6MWT -31m (p<.001), mMRC ≥ 2 OR 1.28 (p=.15) and SpO2 ≤89% OR 1.12 (p=.69).
Among COPD patients, women had higher odds of airway MP. We found no evidence for clinically relevant sex differences in most of the outcomes examined, except for FEV1.