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

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.

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.

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).

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.