The burden of progressive fibrotic interstitial lung disease across the UK

While idiopathic pulmonary fibrosis (IPF) remains the exemplar progressive fibrotic lung disease, there remains a cohort of non-IPF fibrotic lung diseases (fILD) which adopt a similar clinical behaviour to IPF despite therapy 1. This phenotypically related group of conditions, where progression of disease is similar to that seen in IPF, have recently been described as progressive fibrotic interstitial lung diseases (PF-ILD) 2. Historically, treatments for these cases have been limited though given the phenotypic similarities many cases may have been given a multidisciplinary working diagnosis of IPF based on their disease behaviour 3. The INBUILD trial broadened the scope of treatable fILD by demonstrating a significant benefit of Nintedanib in patients with fILD and progressive disease 4. In response to this the European Commission approved an additional indication for nintedanib in adults for the treatment of PF-ILD in July 2020. Almost 15% of new referrals with non-IPF fibrotic ILD go on to develop a progressive fibrotic phenotype and would benefit from antifibrotic therapy