Treatment response in hypersensitivity pneumonitis

Abstract

Introduction: Data about treatment response in hypersensitivity pneumonitis (HP) is scant, especially in chronic HP (ChHP).

Objective: To compare treatment response between ChHP and subacute HP (SaHP).

Methods: Retrospective analytical study, from March 2012 to December 2015. Diagnostic criteria for HP were positive antigen exposure source or typical findings in high-resolution computed tomography (HRCT) plus at least one of the following: bronchoalveolar lavage lymphocytosis (>20%), diagnostic transbronchial lung biopsy and/or surgical biopsy. ChHP was considered if any typical HRCT findings [ground glass opacities, centrilobular nodules, and mosaic perfusion] were associated with traction bronchiectasis, septal thickening or honeycombing; or with histopathological features of ChHP. Patients characteristics and treatment response were analysed. Wilcoxson Rank sum test was used to compare quantitative variables. Significance was defined as a p-value of <0.05.

Results: 25 patients, 76% female and 56% ChHP. Median age at diagnosis was 57 (IQR 45-66). Main antigen source were: home environment (10), pigeons and other birds (8), and feather bedding (4). Antigen avoidance was advised, all received steroid treatment, azathioprine was added in 11 while mycophenolate in 4. Median treatment follow up in months was similar in both groups [ChHP 9 (IQR 7- 50) vs SaHP 8 (IQR 3-33); p: 0.27]. Percentage of the predicted forced vital capacity (FVC%) declined among ChHP cases, in contrast to SaHP [- 4 (IQR -10.5to 6.5) vs 15 (IQR 9.5to34); p 0.015].

Conclusion: Patients with ChHP had a greater functional decline despite antigen avoidance and immunosuppressive therapy. Fibrotic changes in HRCT and histopathology might influence treatment response.