CHICAGO – than are those with idiopathic interstitial lung disease who don’t meet the criteria, Michail Alevizos, MD, reported at the annual meeting of the American College of Rheumatology.
Bruce Jancin/MDedge News
Dr. Michail Alevizos
“We think this is a very novel finding. It means that patients with IPAF [interstitial pneumonia with autoimmune features] should be followed and evaluated by rheumatologists over time,” said Dr. Alevizos, who was a rheumatology fellow at Columbia University in New York at the time of the study.
Interstitial pneumonia with autoimmune features (IPAF) is a term proposed by a joint task force of the American Thoracic Society and European Respiratory Society in 2015 to describe patients diagnosed with idiopathic interstitial lung disease who possess some features of autoimmunity without meeting formal criteria for a full-blown rheumatic disease. The designation requires the presence of interstitial lung disease by imaging or biopsy, exclusion of all other etiologies, and at least one feature from within at least two of three domains: clinical, serologic, and morphologic.
The clinical domain includes Raynaud’s, palmar telangiectasias, distal digital tip ulceration, and other entities. The serologic criteria include any of a dozen possible autoantibodies. And the morphologic domain encompasses a radiographic or histopathologic pattern suggestive of organizing pneumonia, nonspecific interstitial pneumonia, or other specific abnormalities (Eur Respir J. 2015 Oct;46[4]:976-87).
The natural history of IPAF is largely unknown, which was the impetus for Dr. Alevizos’ study. He presented a single-center, retrospective study of 697 patients diagnosed with interstitial lung disease, 174 of whom had idiopathic interstitial lung disease at baseline. Fifty of the 174 met criteria for IPAF, while the other 124 did not.
During a median follow-up of 5.2 years, 8 of the 50 patients with IPAF (16%) were diagnosed with a systemic autoimmune rheumatic disease, as were 2 of the 124 non-IPAF group (1.6%). The average time to diagnosis of a formal rheumatic disease was 3.4 years in the IPAF group and 7.8 years in the comparator arm. The rheumatic diseases that arose in the IPAF group consisted of two cases of rheumatoid arthritis, two of antineutrophil cytoplasmic antibody–associated vasculitis, three of systemic sclerosis, and one of polymyositis.
In an analysis adjusted for age, sex, smoking status, and immunosuppressive therapy at baseline, patients with IPAF were 14.1 times more likely to progress to an autoimmune rheumatic disease.
In terms of distinguishing features, the IPAF patients were on average 10 years younger at baseline and more commonly female. On high-resolution CT, 82% of them displayed a pattern of nonspecific interstitial pneumonia, compared with only 15% of the non-IPAF group. Also, 96% of the IPAF patients were on immunosuppressive therapy at baseline, as were 52% of the non-IPAF group. Usual interstitial pneumonia was evident on high-resolution CT in 18% of the IPAF group, compared with 75% of patients with idiopathic interstitial pneumonia without IPAF.
Dr. Alevizos said he hopes to validate these findings in a prospective study. He reported having no financial conflicts regarding the study, which was conducted free of commercial support.
SOURCE: Alevizos M et al. Arthritis Rheumatol. 2018;70(Suppl 10), Abstract 1305.