Characterizing Cough and Its Response to Therapy in Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease driven by repeated antigen exposure in susceptible individuals. Cough is a prominent but poorly characterized symptom, especially in relationship to objective measures and treatment response.

What are the clinical predictors of cough severity in HP, and how does cough respond to corticosteroid therapy based on subjective and objective assessments?

A prospective cohort of patients with fibrotic HP diagnosed per American Thoracic Society/Japanese Respiratory Society/Asociación Latinoamericana del Tórax guidelines was recruited. Baseline assessments included cough visual analog scale (VAS) and Leicester Cough Questionnaire (LCQ) score. Cough frequency was assessed using the VitaloJAK (Vitalograph) cough monitor in a subset of patients. Multivariable models evaluated predictors of cough severity, and in incident cases, changes in cough outcomes were evaluated after 3 months of corticosteroid therapy.

A total of 101 patients were recruited (41 male patients; mean age, 65 years). The median cough VAS was 35 mm (interquartile range [IQR], 14-50 mm) and the median LCQ score was 15.2 (IQR, 13.2-17.4). The median cough count was 8.7/h (range, 0.2-32.1/h; n = 28). Subjective cough scores correlated with objective cough frequency (cough VAS, ρ = 0.69 [P < .001] and LCQ score, ρ = -0.555 [P = .002]). Female sex, reduced FVC, and higher bronchoalveloar lavage lymphocyte fractions were independent predictors of worse cough severity, as measured by cough VAS. Corticosteroids significantly improved cough subjectively (cough VAS, -13.7 mm [P = .002] and LCQ score, +1.9 [P < .001]; n = 44), but did not significantly reduce objective cough frequency (n = 16). Lung function remained unchanged at 3 months.

Our results show that cough is a major symptom for patients with HP. Although corticosteroids improved subjective cough, no impact on objective cough count was found. Randomized controlled trials are required to validate these findings and to provide evidence for more effective treatments.