The incidence of Progressive Fibrotic Interstitial Lung Diseases (PFILD) treatable with oral-antifibrotic therapy in a UK Specialist Interstitial Lung Disease clinic

Abstract

Treatment of Idiopathic Pulmonary Fibrosis (IPF) has evolved dramatically in the last 10 years with the advent of oral anti-fibrotic therapy. Patients with other Interstitial Lung diseases (ILD) are recognised to progress along a similar clinical trajectory to IPF, including the development of radiologically evident Usual Interstitial Pneumonitis (UIP) type fibrotic changes. These include but are not limited to: Fibrotic Non-specific Interstitial Pneumonitis (fNSIP), Chronic Hypersensitivity Pneumonitis (CHP), Auto-immune Interstitial Lung Diseases and Unclassifiable Interstitial Lung Disease. These are now described as Progressive Fibrotic Interstitial Lung diseases (PFILD). The INBUILD Trial (Flaherty et al, 2019) demonstrated significant positive impact of Nintedanib treatment on the rate of decline in Forced Vital Capacity (FVC) amongst patients with a PFILD diagnosed according to specific criteria. We sought to assess the incidence of PFILDs amenable to treatment with within our specialty tertiary referral centre covering London and the south-east of England. All referrals seen for their first appointment between 1st August 2017 and 31st January 2018 were assessed against the diagnostic criteria for PFILD laid out in the INBUILD trial. We screened 303 cases, identifying 23 treatable PFILD cases with an average age of 70. 16 patients were female. The most common diagnoses were: fNSIP, CHP and Pleuro-parenchymal fibroelastosis. At least 7 were dead within 1 year. This data suggests an incidence of treatable PFILD of c.7.5% within our referral population, with obvious consequences for drug spending costs.