Insights on chronic hypersensitivity pneumonitis' treatment: factors associated with a favourable response to azathioprine

Abstract

Background: The use of immunosuppressive and antifibrotic agents for the treatment of chronic hypersensitivity pneumonitis (CHP) appears promising, but there is still no evidence supporting the clinical decision regarding the implementation of each specific pharmacological strategy. Methods: Patients diagnosed with CHP and treated with azathioprine (AZA) were retrospectively selected from a single centre for Interstitial Lung Diseases. Baseline clinical data, as well as functional, imaging, bronchoalveolar lavage (BAL) and histology features were assessed. Longitudinal data on functional parameters were collected and comparatively analysed with patients' characteristics. Results: In this cohort of 80 patients, of those who reached 12 months of treatment, 78.3% presented a preserved forced vital capacity, with 59 being eligible to be classified as AZA responders (n = 36) or non-responders (n = 23). BAL lymphocytosis was associated with a favourable response to AZA treatment (OR 1.051; 95% CI 1.015-1.089), although it didn't identify all responders. Conclusions: AZA revealed to be effective in disease stabilisation in most patients, while ineffective for a subset. BAL lymphocytosis appears as a potentially valuable strategy to identify AZA responders, although with limited accuracy. Further studies are needed to clarify other response markers to immunosuppressive agents, in order to optimize the therapeutic options for this condition.