Interstitial pneumonia with autoimmune features (IPAF) describes a rare condition characterized by interstitial lung disease (ILD) with autoimmune manifestations in the absence of defined autoimmune rheumatic diseases (AIRD). Although the classification was established in 2015, prospective data on disease progression remain limited. To identify predictors of ILD progression in IPAF patients using three criteria: 1) progressive pulmonary fibrosis (PPF), 2) INBUILD criteria, 3) absolute FVC decline ≥10%. A secondary aim was to compare bronchoalveolar lavage fluid (BALF) cellular profiles between IPAF and AIRD-ILD and explore their prognostic value. Between March 2021 and November 2022, 69 patients were prospectively recruited: 31 with IPAF and 38 with AIRD-ILD. Clinical, laboratory, radiological, pulmonary function and BALF data were analyzed. Univariable and multivariable logistic regression were used to assess one-year progression predictors. Among IPAF patients, 43.3% met PPF criteria, 36.7% met INBUILD and 22.2% had FVC decline ≥10%. PPF-defined progression was more frequent in IPAF than AIRD-ILD (43.3% vs. 19.35%, p = 0.04). Predictors of progression per PPF criteria included elevated peripheral blood neutrophil count (OR = 1.89, 95% CI: 1.08-3.31; p = 0.03) and usual interstitial pneumonia pattern on HRCT (OR = 43.8, 95% CI: 1.52-1260; p = 0.03). BALF lymphocyte count was not associated with progression (OR = 1.10, p = 0.07). For INBUILD criteria, predictors were peripheral blood neutrophil count (OR = 2.06, 95% CI: 1.19-3.59; p = 0.01) and honeycombing (OR = 69.1, 95% CI:2.16-2220; p = 0.02). Antinuclear antibody titer had no impact on IPAF progression. Fibrotic HRCT features (UIP, honeycombing) and peripheral neutrophilia were predictors of ILD short-term progression in IPAF.
Miądlikowska et al. (Mon,) studied this question.