Clinical Characteristics and Natural History of Autoimmune Forms of Interstitial Lung Disease: A Single-Center Experience.

OBJECTIVE: To describe the phenotypic characteristics and natural history of patients with autoimmune forms of interstitial lung disease (ILD). METHODS: Retrospective, descriptive, single-center study of patients with autoimmune forms of ILD evaluated between February 2008 and August 2014. All data were extracted from the electronic medical record. Longitudinal changes in forced vital capacity (FVC%) and diffusion capacity for carbon monoxide (DLco%) in percent predicted were analyzed and time-to-event analyses for death were performed using Cox regression. RESULTS: Of the entire cohort (n = 243), systemic sclerosis (SSc)-associated ILD (n = 88, 36%), interstitial pneumonia with autoimmune features (IPAF, n = 56, 23%), rheumatoid arthritis (RA)-associated ILD (n = 42, 17%), and idiopathic inflammatory myopathy (IIM)-associated ILD (n = 26, 11%) were the most common phenotypes. The SSc-ILD, IIM-ILD, and IPAF groups had similar features: average age in the mid-50s, strongly female predominant and more likely to have nonspecific interstitial pneumonia (NSIP). In contrast, RA-ILD patients were older, gender balanced, more likely to be past smokers and were UIP predominant. Adjusted longitudinal lung function was stable during a median follow-up period of nearly 4 years and the independent predictors for death were older age (p = 0.003), male sex (p = 0.019), and lower FVC (p = < 0.001). CONCLUSIONS: The predominant phenotypes of autoimmune ILD were SSc-ILD, IPAF, RA-ILD, and IIM-ILD. In contrast to the other subsets, those with RA-ILD may be older, gender balanced, with more smoking history, and higher proportion of UIP. Longitudinal lung function was stable among the groups and younger age, female gender, and better lung function were associated with improved survival.

Clinical features and natural history of interstitial pneumonia with autoimmune features: A single center experience.

OBJECTIVE: To describe the clinical phenotype and natural history of a cohort of patients with interstitial pneumonia with autoimmune features (IPAF). METHODS: A retrospective, single center study of 56 patients with IPAF evaluated between February 2008 and August 2014. All clinical data were extracted from the electronic medical record and longitudinal changes in forced vital capacity (FVC) were analyzed with mixed-effects, piecewise linear regression models that considered time as a continuous factor. RESULTS: All patients fulfilled classification criteria for IPAF. The majority were women (71%) and never smokers (68%). The most frequently identified clinical features were Raynaud's phenomenon (39%), distal digital fissuring (29%), Gottron's sign (18%) and inflammatory arthropathy (16%). The most frequently identified serologies were antinuclear antibody (ANA) (48%), anti-Ro (SSA) (43%) and anti-tRNA-synthetase antibodies (36%). Nonspecific interstitial pneumonia (NSIP) (57.1%) followed by NSIP with organizing pneumonia (18%) were the most common radiologic patterns, while usual interstitial pneumonia was identified in only 9%. All but one patient was treated with immunosuppression: prednisone (82%) and mycophenolate mofetil (76%) were the most frequently used agents. During a follow-up period of 284.9 ± 141.3 days, modeled longitudinal FVC% was stable (slope = 0.69/year) and no deaths were observed in the cohort. CONCLUSIONS: In this single center study, patients with IPAF were predominately non-smoking women with high-resolution computed tomography scans that suggested NSIP. Their pulmonary physiology was stable, and during limited follow-up, no deaths were observed. Prospective and multi-center studies are needed to better inform our understanding of IPAF.