Clinical experience with antifibrotics in fibrotic hypersensitivity pneumonitis: a 3-year real-life observational study

Background: Fibrotic hypersensitivity pneumonitis ( f-HP) can exhibit a progressive course similar to idiopathic pulmonary fibrosis (IPF). The lack of diagnostic guidelines and randomised controlled trials in this population represent a significant unmet need. Objectives: To describe our clinical experience with antifibrotics in patients with f-HP. Material and methods: Retrospective study of 30 patients diagnosed with f-HP upon re-evaluation within a multidisciplinary team discussion of 295 consecutive patients ( January 2012 to December 2017) who had been diagnosed initially with IPF at outside facilities and were referred to our centres. Results: Pirfenidone was initially administered to 14 (46.7%) patients and nintedanib to 16 (53.3%) patients. There were 26 (86.7%) males, with mean +/- SD age 70.2 +/- 8.4 years. The annual rate of decline in forced vital capacity (FVC) % predicted over the 3-year treatment period adjusted for baseline FVC % pred measurement was 4.2% (95% CI 1.9-6.6%, p=0.001) and 7.5% (95% CI 3.3-11.7%; p=0.001) in imputation analysis. The annual rate of decline in diffusing capacity of the lung for carbon monoxide ( DLCO) % predicted throughout the 3-year treatment period adjusted for baseline D-LCO % pred was 5.7% (95% CI 3.1-8.4%, p<0.001) and 5.8% (95% CI 3.4-8.1%, p<0.001) in imputation analysis. The nature of adverse events was related to the type of antifibrotic agent administered. Conclusion: In patients with f-HP receiving antifibrotics there is a statistically significant annual decline in FVC % pred and DLCO % pred over a period of 3 years. Prospective randomised trials exceeding 1 year are warranted to determine the long-term efficacy of antifibrotics.