Stratifying GAP Stages by MUC5B rs35705950 T-Allele Carriage Refines Survival Prediction in IPF

The genetic contribution to idiopathic pulmonary fibrosis (IPF) has become increasingly evident, enabling its translation into clinical practice. MUC5B rs35705950 has emerged as a promising prognostic biomarker. The gender-age-physiology (GAP)-model is regularly used for IPF survival prediction. In this retrospective real-world study, GAP-stages were stratified by MUC5B T-allele carriage. European patients with IPF were included in a discovery (n = 663), and replication (n = 738) cohort. The GAP+MUC5B-model was significantly more accurate compared to the GAP-model (all cohorts p < 0.001), with a modest improvement in discrimination (ΔC = 0.023; C = 0.685, 95%CI 0.665-0.704). Within each GAP-stage, T-allele carriers had significantly better median transplant-free survival outcomes than non-carriers (p < 0.001): In the combined cohort (n = 1401) survival for GAP-stage I T carriers was 70 months (m) vs 48m for T non-carriers; stage II T vs non-T: 41 vs 31m; stage III T vs non-T: 23 vs 12m. Addition of MUC5B rs35705950 T-carriership enhances GAP-based prognostication and aids clinical decision-making.