Measuring the impact of changing from standard half-life (SHL) to extended half-life (EHL) FVIII prophylaxis on health-related quality of life (HRQoL) in boys with moderate/severe haemophilia A: Lessons learned with the CHO-KLAT tool

Introduction: In many countries, there is a shift from standard half-life (SHL) to extended half-life (EHL) clotting factor concentrates (CFCs). Aim: To describe the experience of switching from SHL to an EHL FVIII CFC and the impact of this on frequency of infusions, factor consumption, bleeding rates and HRQoL using the Canadian Hemophilia Kids’ Life Assessment Tool (CHO-KLAT). Methods: A retrospective chart review was conducted at a single haemophilia treatment centre in 2018 that included boys (ages: 4-18 years) with moderate/severe haemophilia A, without inhibitors, who switched from a SHL to an EHL FVIII CFC in the previous 2 years and for whom HRQoL data were available. Results: The study cohort comprised 38 boys [mean (SD) age: 11.0 (3.4) years] with moderate (n = 5)/severe (n = 33) haemophilia A. The switch was associated with a 33% reduction in the number of weekly infusions from a median of 3.5 to 2.3 (P <.0001) and a 17% reduction in median FVIII consumption from 103 IU/kg/wk to 85.5 IU/kg/wk (P =.004). There was no significant change in annualized joint bleed rates or in CHO-KLAT scores. Conclusions: Despite documenting several benefits of switching to EHL FVIII (less infusions, lower factor consumption with no increase in bleeding), our study did not demonstrate any improvement in HRQoL. We conclude that either the current CHO-KLAT tool is not optimized to measure burden of treatment administration in boys with low bleed rates switching from SHL to EHL FVIII CFCs or that a reduction of 1.2 infusions/week does not result in a meaningful change in HRQoL.