Introduction: Hypersensitivity pneumonitis (HP) is an ILD characterized by a complex immunological reaction of the lung parenchyma in response to repetitive inhalation of a sensitized allergen. Patients with HP and presence of fibrosis have worse outcome.

Aim and objectives: To evaluate tretment response and the annual change in lung function tests in patients with fibrotic and non-fibrotic HP.

Methods: In this retrospective, observational study, data were collected from patients treated in our Clinic during the last 10 years. We analyzed demographic, radiological findings, the annual rate of lung function change (FVC, DLCO) during the therapy, and threatment approach.

Results: We included 83 patients; 47 females and 36 males; 49 patients had fibrotic, and 34 had non-fibrotic HP. Among patients with non-fibrotic HP, 85% patients were treated only with glucocorticoids versus 40% patients in fibrotic group. In non-fibrotic group 6% patients were treated with steroid sparing agents versus 57% patients in fibrotic group. After 1 year of treatment in fibrotic group 61% patients had significant decline of FVC and 48.9% of DLCO while in non-fibrotic HP FVC declined in 38.2% and DLCO in 26.5% patients. Improvement of FVC (for 8%) was observed in 39% patients from fibrotic group and in 43% patients of DLCO (for 9%) while in non-fibrotic group significant increase of FVC (for 17%) was observed in 59% and of DLCO (for 18%) in 68% patients.

Conclusion: Glucocorticoids were treatment option for most of the patients with HP. Despite the more agressive treatment approach most patients with fibrotic HP had greater decline in FVC and DLCO and further treatment options are needed.