D13-03 Association of Muscle, Fat, and Bone With Mucus Plugs in Individuals Exposed to Tobacco: Findings From the COPDGene and ECLIPSE Studies

Rationale Mucus plugs (MPs) on computed tomography (CT) have been associated with low body mass index; however, whether BMI components, including muscle, fat, and bone, are associated with MPs is unknown. Methods We analyzed tobacco-exposed participants with and without COPD enrolled in phase 1 of the COPDGene study (n = 9,112). The findings were validated in participants with Global Initiative for Obstructive Lung Disease (GOLD) grades 2-4 COPD of the COPDGene and Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) studies (n = 1698). The pectoralis muscle area index (PMAi, cm2/height in m2) and its corresponding subcutaneous adipose tissue area index (SATi, cm2/height in m2) were quantified in cross-sectional CTs at the aortic arch level (COPDGene). The fat-free mass index (FFMi, kg/m2) was estimated by bioelectrical impedance (ECLIPSE). A history of osteoporosis was self-reported. In both studies, MPs were defined as airway-occluding opacities on inspiratory CTs. Separate ordinal logistic multivariable models were performed to assess the association of PMAi (continuous), FFMi (continuous), SATi (continuous), and osteoporosis (yes/no) with MPs (categorized as 0 [reference] vs. ≥1 and 0-2 [reference] vs. ≥3) (Table 1). Results Among COPDGene participants with 0, 1-2, and ≥3 lung segments affected by MPs, the mean PMAi (cm²/m²) was 15 ± 5.4, 13.3 ± 4.7, and 12 ± 4. The mean SATi (cm²/m²) was 21 ± 13.9, 19.9 ± 12.9, and 17.7 ± 10.9. The prevalence of osteoporosis was 7%, 10%, and 17%, respectively. Likewise, in ECLIPSE participants, the mean FFMi (kg/m2) was 17.6 ± 3, 16.8 ± 2.7, and 16.4 ± 2.5, and the prevalence of osteoporosis was 12%, 20%, and 16%. In the entire COPDGene cohort, PMAi (lung segments affected; ≥1 vs. 0, adjusted odds ratio [aOR]=1.06 [confidence interval 1.05-1.08], p < 0.001 and ≥3 vs. 0-2, aOR=1.07 [1.05-1.10], p < 0.001) and SATi (≥1 vs. 0, aOR= 1.03 [1.03-1.04], p < 0.001 and ≥3 vs. 0-2, aOR=1.04 [1.04-1.05], p < 0.001) were inversely associated with MPs. Meanwhile, having osteoporosis was directly associated with MPs (≥3 vs. 0-2, aOR=1.47 [1.17-1.85], p = 0.001). The associations were consistent, but attenuated, among GOLD 2-4 COPDGene participants. In GOLD 2-4 ECLIPSE individuals, FFMi was inversely associated with MPs (≥1 vs. 0, aOR=1.15 [1.10-1.20], p < 0.001 and ≥3 vs. 0-2, aOR=1.16 [1.10-1.21], p < 0.001), and osteoporosis was directly associated with MPs (≥1 vs. 0, aOR=1.52 [1.05-2.22], p = 0.029)—(Table 1). Conclusions Among tobacco-exposed participants, muscle loss, fat loss, and osteoporosis were each independently associated with more MPs.