Clinical outcome and adherence rate in Scandinavian patients with intermediate‐intensity prophylaxis before and after the switch of standard half‐life FVIII products to BAY 81–8973

Introduction Treatment optimization in haemophilia A can be achieved by choice of FVIII product and knowledge of pharmacokinetics (PK), phenotype and adherence. A favourable PK profile of BAY 81–8973 (octocog alfa) (Kovaltry, Bayer AB) compared to other standard half-life (SHL) FVIII products has been suggested. Aim To evaluate whether the switch to BAY 81–8973, using the same dosing schedule, impact factor consumption and bleed rates, taking arthropathy and adherence into account Methods Forty patients on prophylaxis with SHL (median age 40.5 years) attending the haemophilia treatment centres in Malmö and Oslo were enrolled. The annualised bleeding rate (ABR) and joint bleeding rate (AJBR) before and after the switch to BAY 81–8973 was calculated. PK analyses were performed with WAPPS-Hemo. Joint health status and treatment adherence were assessed. Results The median ABR and AJBR was 0 before and after the switch, at both centres. The median yearly factor consumption was 3,345 IU/Kg/year in the entire study group corresponding to intermediate-intensity prophylaxis in most patients and with significantly more used in Malmö (3,862 IU/Kg/year), compared to Oslo (2,337 IU/Kg/year) (P .006). There was no correlation between arthropathy and bleeding. The median BAY 81–8973 t½ was 15.15 h (range 7.5–29 h), with significant correlation to VWF levels, and 13.4 h after exclusion of VWF outliers. Adherence to treatment was 97%. Conclusions Concentrate switch, using mainly intermediate-intensity regimens with high adherence rates, preserves excellent prophylaxis outcome using standard half-life FVIII products, indicating the value of individualized prophylaxis and close follow-up.