Objective:
To analyse real world FVIII dosing and treatment interval patterns in patients with haemophilia A. A secondary objective was to compare the observed dosing patterns with the dosing regimens for rFVIII and rFVIIIFc evaluated in clinical studies.
Methods:
A retrospective analysis was conducted using aggregate Specialty Pharmacy Provider (SPP) records from Nov 2013 through Mar 2014. SPP data included 63 different attributes for each prescription, including trade name, National Drug Code (NDC), drug quantity shipped, prescribed infusion dose, days supplied, and dose frequency. Patients were considered eligible for the analysis if they received a shipment of any FVIII product. Patients were excluded from the analysis if they were being treated episodically, for immune tolerance induction, or their pharmacy records did not specify a prescribed infusion dose. Patients with missing or extremely abnormal weights were also excluded. The patient’s weekly consumption was calculated for each shipment record by multiplying the prescribed infusion dose by the dose frequency and dividing the product by the patient’s weight, resulting in the patient’s average weekly prescribed dose (IU/kg/week). Patients were also categorized according to their dosing interval.
Summary:
The analysis included 520 hemophilia A patients with a median age of 18 (range: 1-77) and median weight of 63.5 kg (range: 8-161 kg). Pharmacy dispensing records represented 227 distinct prescribers across 43 states. FVIII therapies evaluated included Advate®, Recombinate®, Helixate® FS, Kogenate®, Hemofil and Xyntha®. The average weekly consumption across all therapies was 108.0 IU/kg/week (95% CI, 104.6-111.5). Dosing frequency ranged from once-daily to once-weekly with three times/week and every other day as the most common dosing intervals, representing 81.3% of patient records. For patients infusing thrice-weekly, the average infusion dose was 35.1 IU/Kg. Only 15.4% of the population was infusing ≤ two times per week. Clinical trials for Advate report weekly consumption of 110.3 IU/kg (31.4 IU/kg administered QOD). Two prophylactic regimens were evaluated for rFVIIIFc in A-LONG. In the last 3 months of this study, the median weekly consumption was 77.7 IU/kg for the individualized prophylaxis and the median weekly dose of 65.5 IU/kg for the weekly prophylaxis regimen.
Conclusions:
Pharmacy dispensing records support the clinical trial dosing intervals of rFVIII products currently requiring every other day or thrice-weekly dosing; however, real-world dosing (IU/kg/week) may be greater. This may result in unpredictability for payers who are responsible for healthcare budgets.