Clinical, serological and radiological features of a prospective cohort of Interstitial Pneumonia with Autoimmune Features (IPAF) patients

Abstract

Background: The term Interstitial Pneumonia with Autoimmune Features (IPAF) describes patients with Interstitial Lung Diseases (ILDs) and clinical or serological features of autoimmune diseases insufficient to reach a specific classification of a Connective Tissue Disease (CTD). Currently, retrospective studies on IPAF patients have proven to be heterogeneous in general characteristics, outcomes and High-Resolution Computed Tomography (HRCT) pattern. This study aims to describe for the first time the clinical, serological and radiological features of a prospective cohort of IPAF patients. This cohort is then compared to a group of patients with Idiopathic Pulmonary Fibrosis (IPF).

Material and methods: From 626 consecutive ILD patients evaluated, 45 IPAF and a comparison cohort of 143 IPF patients were enrolled. All patients underwent clinical assessment with rheumatologic and respiratory evaluation, HRCT, Pulmonary Function Tests and Nailfold Videocapillaroscopy.

Results: The IPAF patients had a predominance of female gender (62.12%) with a median age of 66 years. The most common findings were: Nonspecific Interstitial Pneumonia (NSIP, 68.89%), Antinuclear Antibody positivity (17.77%) and Raynaud Phenomenon (31.11%). In comparison with IPF, IPAF patients showed younger age, better performances in Pulmonary Function Tests, less necessity of O₂ support and predominance of female sex and NSIP pattern.

Discussion: This is the first report of a prospective cohort of IPAF patients. IPAF patients seem to have a less severe lung disease than IPF. IPAF criteria probably need to be revisited and validated, but their capacity to recruit patients with incomplete forms or early onset of CTD could be useful for further research.

Keywords: Classification criteria; Diagnosis; Idiopathic pulmonary fibrosis; Interstitial Pneumonia with autoimmune features; Interstitial lung disease; Undifferentiated connective tissue disease.