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.