Impact of Azathioprine use in chronic hypersensitivity pneumonitis patients

Systemic corticosteroids are widely used in chronic hypersensitivity pneumonitis (CHP); however, there is not much evidence to support their use, besides being associated with significant side effects. Azathioprine (AZA) use is common in CHP, although not prospectively tested in randomized controlled trials. Our objective was to evaluate the lung function trajectory of CHP patients after AZA initiation, as well as to assess the safety profile of this drug. Retrospective analysis of patients initiated on AZA following a multidisciplinary team diagnosis of CHP. The longitudinal trajectory of lung function in the first 2 years of treatment was assessed. Thirty-five out of 62 patients (56.5%) remained on treatment after 2 years. AZA treatment was associated with a significant improvement in forced vital capacity (FVC) at 12 and 24 months (p = 0.015 and p