Retrospective study of predictors of pulmonary fibrosis progression in hypersensitivity pneumonitis

Introduction. Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease (ILD). Fibrotic HP is associated with disease progression, impaired lung function, and poor clinical outcomes. Aim. Identify factors that increase the risk of progression of pulmonary fibrosis in patients with HP. Materials and methods. We conducted a retrospective multicenter observational study analyzing data from a fibrosing ILD registry (n = 1355). The study included 292 patients with chronic HP confirmed by multidisciplinary discussion. We evaluated clinical, functional, and laboratory parameters, including 6-minute walk test results and echocardiography findings at baseline and 12-month follow-up. Risk factors for progression were identified through correlation and regression analyses. ROC curve analysis and Kaplan-Meier survival analysis were performed to assess the prognostic significance of various parameters. Results. Among 292 chronic HP patients, fibrosis prevalence was 91.8% with 14.5% mortality. Patients were stratified into progressive fibrosis (n = 92, 30.3%) and non-progressive (n = 200, 69.7%) groups. Regression analysis identified significant predictors of progression: male sex (OR 1.68, 95% CI 1.02–2.76, p = 0,041), smoking (OR 1.1, 95% CI 1.0–1.1, p = 0,002), Charlson Comorbidity Index (OR 1,48, 95% CI 1.03–2.12, p = 0.036), GAP score (OR 1.57, 95% CI 1.1–2.3, p = 0,015), and DLco % predicted (OR 0.93, 95% CI 0.89–0.97, p = 0.001). ROC analysis revealed DLco <50% predicted (p = 0.0001), GAP score ≥4 (p = 0.03), and Charlson Index ≥3 (p = 0.04) as significant progression factors. Conclusion. Patients with fibrotic HP demonstrate high rates of pulmonary fibrosis progression. The main progression predictors include male sex, smoking, higher Charlson Comorbidity Index, DLco < 50% predicted, and GAP score ≥ 4.