Association between adherence patterns to antifibrotic therapy and survival in fibrotic interstitial lung disease: a nationwide Austrian health claims study

Antifibrotic therapies slow disease progression in patients with progressive fibrosing interstitial lung diseases (PF-ILD). However, long-term adherence is difficult to maintain mainly due to side effects. Real-world data on adherence and its association with prognosis are still limited. Health claims data of patients having been prescribed nintedanib or pirfenidone between 2019 and 2024 were retrieved by the Austrian Health Insurance Fund (ÖGK). Patients who died within four months of treatment initiation were excluded. Adherence was defined as prescription of ≥ 10 monthly dose packages of either medication. Overall (OS) and event-free survival (EFS, defined as hospitalisation or death) and their determinants were examined. Additionally, an analysis of nintedanib dose-adjustment strategies was performed to assess their association with overall survival. Of 1,797 patients identified, 1,567 were available for the adherence analysis. Adherent patients ( n = 949; 60,6%) had significantly longer survival than non-adherent patients (median OS 66 vs. 47 months; p < 0.001). EFS was also prolonged (33 vs. 16 months; p < 0.001). In multivariate analysis, adherence was an independent protective variable (HR 0.42; 95% CI 0.34–0.50), while age ≥ 70 years, male sex, pre-existing long-term oxygen therapy and hospitalisations in the previous year were associated with increased mortality. There was no difference in survival between nintedanib and pirfenidone. With nintedanib, dose-reduction as well as dose-escalation schedules were not associated with a worse prognosis, while patients on continued lower-dose treatment had poorer outcomes ( p < 0.0001). In this large, nationwide real-world cohort, higher adherence to antifibrotic therapy was associated with improved survival outcomes. Individualised dose management strategies may help to improve treatment persistence and adherence in patients with ILD.