Interstitial pneumonia with autoimmune features: from research classification to diagnosis

Purpose of review The term interstitial pneumonia with autoimmune features (IPAF) was first proposed by an international task force in 2015 as a research classification to standardise nomenclature regarding patients with idiopathic interstitial pneumonia and features of connective tissue disease. However, how the use of this term and its proposed definition translates to clinical practice remains uncertain. This review will provide a comprehensive overview of studies of IPAF cohorts to date, discuss the consideration of IPAF as a distinct diagnostic entity and outline a suggested approach to patient management. Recent findings Considerable heterogeneity exists between published IPAF cohorts, with some cohorts exhibiting similarities to those with connective tissue disease-associated interstitial lung disease (CTD-ILD), and others more similar to idiopathic interstitial pneumonias including idiopathic pulmonary fibrosis (IPF). Little data exist to inform the management of patients who fulfil the IPAF criteria. Preliminary data supports pragmatic management of these patients as having a working clinical diagnosis of either idiopathic interstitial pneumonia or CTD-ILD. Future research studies into this approach are required. The term IPAF, and its definition, have been of fundamental benefit to facilitating research in this diverse patient group. However, to date, there remain many unanswered questions regarding their natural histories and response to treatment.