Idiopathic Interstitial Pneumonia Associated With Autoantibodies: A Large Case Series Followed Over 1 Year

• Published in: Chest Vol. 152; no. 1; pp. 103 - 112
• Main Authors: Collins, Bridget F, Spiekerman, Charles F, Shaw, Megan A, Ho, Lawrence A, Hayes, Jennifer, Spada, Carolyn A, Stamato, Caroline M, Raghu, Ganesh
• Format: Journal Article
• Language: English
• Published: United States American College of Chest Physicians 01-07-2017
• Subjects: Aged; Autoantibodies - blood; Autoimmunity - immunology; Cohort Studies; Connective Tissue Diseases - diagnosis; Connective Tissue Diseases - physiopathology; Diagnosis, Differential; Diffuse Lung Disease; Female; Follow-Up Studies; Humans; Idiopathic Interstitial Pneumonias - diagnosis; Idiopathic Interstitial Pneumonias - epidemiology; Idiopathic Interstitial Pneumonias - immunology; Idiopathic Interstitial Pneumonias - physiopathology; Idiopathic Pulmonary Fibrosis - diagnosis; Idiopathic Pulmonary Fibrosis - immunology; Idiopathic Pulmonary Fibrosis - physiopathology; Lung - diagnostic imaging; Lung - physiopathology; Lung Diseases, Interstitial - diagnosis; Lung Diseases, Interstitial - immunology; Lung Diseases, Interstitial - physiopathology; Male; Middle Aged; Needs Assessment; Respiratory Function Tests - methods; Statistics as Topic; Tomography, X-Ray Computed - methods; Washington - epidemiology; interstitial pneumonia with autoimmune features; idiopathic pulmonary fibrosis; interstitial lung disease; autoimmune interstitial lung disease
• ISSN: 0012-3692; 1931-3543
• DOI: 10.1016/j.chest.2017.03.004

Some patients with autoimmune characteristics and idiopathic interstitial pneumonia, particularly usual interstitial pneumonia (UIP), do not fit neatly into the category of connective tissue disease-associated interstitial lung disease (CTD-ILD), idiopathic pulmonary fibrosis (IPF), or recently proposed yet to be validated criteria for interstitial pneumonia with autoimmune features (IPAF). Outcomes of these patients are unknown.
This was a retrospective single-center study. Analyses of variance compared differences in mean change in FVC and diffusion capacity (Dlco) over 1 year among 124 well-defined patients (20 patients with positive autoantibodies with or without symptoms of connective tissue disease [AI-ILD], 15 patients with IPAF, 36 patients with CTD-ILD, and 53 patients with IPF with negative CTD serologies [Lone-IPF]).
Of the patients, 75% with AI-ILD, 33% with IPAF, and 33% with CTD-ILD had UIP. Initial FVC and Dlco were similarly moderately reduced across groups. Mean change in FVC over 12 months was as follows: -60 mL (IPAF), -110 mL (AI-ILD), -10 mL (CTD-ILD), and -90 mL (Lone-IPF) (P = .52). Mean change in Dlco was as follows: 2.39 mL/mm Hg/min (IPAF), -1.15 mL/mm Hg/min (AI-ILD), -0.27 mL/mm Hg/min (CTD-ILD), and -1.05 mL/mm Hg/min (Lone-IPF) (P < .001). By pattern of disease, the mean change in FVC was as follows: -140 mL (UIP), 10 mL (nonspecific interstitial pneumonia), and 12 mL (unclassifiable/other) (P = .001).
No clinically significant differences in pulmonary function to distinguish between patients with AI-ILD, IPAF, CTD-ILD, and Lone-IPF were observed after 1 year. Longer periods of follow-up are needed to understand the outcomes of these patients. It is not yet clear whether AI-ILD is a distinct phenotype or a variant of the newly proposed entity IPAF.