Prophylaxis with recombinant factor IX Fc fusion protein reduces the risk of bleeding and delays time to first spontaneous bleed event in previously untreated patients with haemophilia B: A post hoc analysis of the PUPs B‐LONG study

Haemophilia B (HB), characterised by deficient factor IX (FIX), leads to spontaneous bleeds. Severe cases require prophylactic FIX replacement. This post hoc analysis assessed the first spontaneous bleeds among previously untreated patients (PUPs) with HB treated with recombinant FIX Fc fusion protein (rFIXFc) (NCT02234310) to identify factors influencing bleeds.