Systemic corticosteroid treatment response in hypersensitivity pneumonitis: a single center experience

Aim: Hypersensitivity pneumonitis (HP) is defined as an inflammatory and/or fibrotic immune reaction provoked by an inhalational exposure in susceptible individuals. Initial management of HP patients includes remediation of exposure and treatment with immunosuppressive agents. In this study we aimed to define clinical features and treatment modalities and to evaluate response to corticosteroids in HP patients followed in a single tertiary care setting.
Materials and Methods: The patients with HP diagnosis followed between 1 January 2019 and 31 December 2020 were included in this retrospective study. Firstly, the candidate factors related with treatment response were evaluated by univariate analysis and then the possible factors with p values below 0.15 were evaluated by multiple linear regression model to identify independent predictors of systemic corticosteroid response.
Results: The study population consisted of 50 HP patients and 20 of them (40%) had fibrotic HP. Forty-one (82.0%) patients were followed with a medical treatment for longer than 3 months. Within follow-up period 15 (36.5%) patients didn’t show clinical or radiological response to systemic corticosteroids. Patients without treatment response were presented as fibrotic HP (66.6% vs 26%, p=0.02), had radiological features of fibrosis (86.6% vs 30.7%, p=0.002) and had loss of pulmonary functions (60.0% vs 34.6%, p=0.03) more frequently. Uni-variable analysis revealed that radiological features of fibrosis (OR: 0.07 [95%CI: 0.01-0.42], p=0.003) and mosaic attenuation (OR: 7.0 [95%CI: 0.30-10.07], p=0.08) in HRCT related with corticosteroid treatment response.
Conclusion: Our study suggests radiological features of fibrosis relate with worse clinical and radiological response to corticosteroid treatment. Prospective clinical trials are needed to clarify the role of immunosuppressive therapy in HP patients.