Interstitial pneumonia with autoimmune features: A literature review

Interstitial pneumonia with autoimmune features (IPAF) is a research classification for patients with an idiopathic interstitial pneumonia in whom clinical, serologic, and/or imaging features are consistent with an autoimmune process but criteria for a defined systemic autoimmune rheumatic disease are not met. Since the establishment of classification criteria in 2015, there has been research into the phenotypic and epidemiologic characteristics of the population, the implications of meeting IPAF criteria, the pathophysiologic processes at work, the factors associated with prognosis in patients meeting IPAF criteria, and its treatment. Despite this growing and evolving data, controversies remain around classification criteria, whether IPAF merits designation as a clinical diagnosis, and appropriate treatment regimens. In this review, we summarize the current state of knowledge about IPAF, discuss data that informs management decisions in patients meeting IPAF criteria, and highlight important questions for future research.