Background:
Until recently, the hemophilia B community has only had standard Factor IX (FIX-Fc) products as treatment choices. With the availability of additional standard rFIX products and extended half-life (EHL) rFIX-Fc, there has been much debate (1-4) regarding clinical and cost expectations, balanced with optimizing use in patients. To level the debate, an understanding of real-world prescription costs of patients who switch to EHL FIX-Fc products is warranted.
Objectives:
1) To characterize patients who switch from rFIX to EHL rFIX-Fc, and 2) to understand their change in factor costs.
Methods:
Retrospective analysis using national US specialty pharmacy dispensing databases from Jan 1, 2013-Apr 25, 2015 of Hemophilia B (ICD-9 code 286.1) individuals who switched from rFIX to rFIX-Fc. Descriptive statistics summarized patient characteristics. Patients who had at least 90 days of prescription coverage on both products were included. Utilization was averaged on a monthly basis pre and post switch. Costs were calculated by multiplying the units by the wholesale acquisition prices for each product (Red Book) and the percentage change in cost from rFIX to EHL-rFIX was compared. This analysis studied patients who switched but stayed on similar regimens. Cohorts were characterized as prophylaxis to prophylaxis (P to P), or on-demand to on-demand (OD to OD).
Results:
Sixteen switchers were included in the study. Hemophilia severity was reported as 62.5% severe, 12.5% moderate, 6.25% mild, and 18.75% of unknown severity. The P to P cohort comprised of the majority of patients at 87.5% (n=14) while OD to OD were smaller at 11% (n=2). The median ages for these cohorts were similar. The P to P median age was 15 (range: 5-51) and OD to OD was 14 (range: 13-15) years old. Median prescription costs increased in the P to P cohort by 40% (range: -56% to 181%), while OD to OD increased by 173% (range: 1% to 348%).
Conclusion:
While the availability of EHL rFIX-Fc allows hemophilia B patients an option with less frequent infusions, our findings demonstrate that for those who initially switched from prophylaxis to prophylaxis or from on-demand to on-demand regimens, costs increased for the majority of patients. This analysis provides initial real-world cost data for those who have switched to EHL and may be helpful in decision makers’ understanding of the value of EHL rFIX-Fc in hemophilia B.