Distinctive computed tomography features of chronic obstructive pulmonary disease among dairy farmers and smokers.

Purpose: To assess whether Chronic Obstructive Pulmonary Disease (COPD) associated with dairy farming presents distinct chest computed tomography (CT) features compared to smoking-related COPD and mixed-exposure COPD.

Materials And Methods: We analyzed data from a prospective monocentric cohort of COPD patients categorized into three groups: non-smoking dairy farmers (F-COPD), smoking dairy farmers (M-COPD), and individuals with smoking related COPD without occupational exposure (S-COPD). All participants underwent chest CT at inclusion. Two radiologists, blinded to exposure status, independently assessed imaging features using standardized criteria.

Results: A total of 85 patients were included, with a mean age of 67 ± 9 years; 72 (85 %) were men. Emphysema was significantly less frequent in F-COPD (54.2 %) than in M-COPD (80.8 %) and S-COPD (80.0 %) (p = 0.05). Paraseptal emphysema was nearly absent in F-COPD (7 %) but prevalent in M-COPD (57 %) and S-COPD (75 %) (p < 0.001). Mucus plug score was highest in F-COPD than S-COPD (1.17 ± 1.16), followed by by M-COPD (0.80 ± 1.05) and S-COPD (0.37 ± 0.77) (p = 0.04). Smoking-related features such as airway enlargement with fibrosis and pulmonary nodules were significantly less common in F-COPD. Tobacco exposure was lower in M-COPD than in S-COPD (p = 0.02).

Conclusion: F-COPD exhibits a distinct, airway-dominant CT-phenotype with prominent mucus plugging and limited emphysema, suggesting a different pathophysiological mechanism driven by chronic exposure to organic dusts and bioaerosols in dairy farming. These findings support the use of chest CT for exposure-specific phenotyping and highlight the need for tailored therapeutic approaches in occupational COPD.