Interstitial pneumonia with autoimmune features

Interstitial pneumonia with autoimmune features (IPAF) is a research classification proposed to describe individuals with idiopathic interstitial pneumonia who have combinations of clinical, serologic, and/or thoracic morphologic features of a systemic autoimmune condition yet who fail to meet established criteria for an underlying connective tissue disease (CTD). Since its inception, several studies have retrospectively applied the classification criteria and have yielded significant heterogeneity across cohorts with regards to the characteristics of patients identified with IPAF, suggesting further refinement of the criteria is necessary. Nonetheless, those with IPAF seem to have an overall prognosis that is likely worse than those with defined CTD-associated interstitial lung disease and better than those with idiopathic pulmonary fibrosis. The optimal treatment of IPAF is unknown though evidence is emerging for the use of antifibrotics for those with a progressive fibrosing phenotype. Further research is needed to elucidate which elements of the clinical, serologic, and morphologic domains confer the most prognostic information to a diagnosis of IPAF to help guide further development of the classification criteria and to facilitate clinical trial design in order to establish standardized treatment approaches.