Interstitial Pneumonia with Autoimmune Features from the Rheumatologists' Perspective; Single Center Experience

Background/Objectives: Interstitial pneumonia with autoimmune features (IPAF) is a recently defined entity characterized by interstitial lung disease (ILD) with clinical, serological, and radiological features suggestive of autoimmunity that do not fulfil the criteria for a defined connective tissue disease (CTD). This study aimed to evaluate the clinical characteristics, treatment modalities, and outcomes of patients with IPAF in a tertiary referral center. Methods: We retrospectively analyzed 72 patients who fulfilled the IPAF classification criteria. Demographic, clinical, serological, radiological, pulmonary function, treatment, and survival data were collected and evaluated. Logistic regression analysis was performed to identify factors associated with mortality. Results: The cohort consisted of 62.5% female patients, with a mean age of 62.7 (SD, 10.4) years at diagnosis. The most frequent radiological pattern was nonspecific interstitial pneumonia (83.3%). Raynaud's phenomenon (6.9%) and arthritis (2.8%) were the most common rheumatological manifestations. Antinuclear antibodies positivity at titers ≥1:320 was observed in 27.8% of patients. Azathioprine was the most frequently prescribed agent (20.8%), followed by mycophenolate mofetil (11.1%). After a median follow-up of 30.1 months (IQR, 52.8), 16 patients (22.22%) died, with a 5-year survival rate of 70%. Glucocorticoid therapy at doses ≥20 mg/day was independently associated with increased mortality (OR 6.13 (95% CI 1.17-32.21). Conclusions: IPAF predominantly affects middle-aged females. Glucocorticoid use at doses ≥20 mg/day was associated with mortality; however, this observational association may reflect underlying disease severity rather than a causal effect of high-dose treatment. Further prospective studies are needed to optimize management strategies in patients with IPAF.