Here is another note from Paul Riley, PhD examining the effects of extended half-life factor IX concentrates. on hemophilia B testing.
Hemophilia B1: Therapy Classes and Monitoring
|Factor IX Inhibitor?||Y/N||Y/N|
|Prophylaxis||Conventional half-life recombinant or plasma-derived FIX||Extended half-life FIX|
|Preferred assay to measure FIX activity||OSA2 (or CSA)||CSA (or OSA)|
1. Discrepancies between once-stage clot-based assay (OSA) and chromogenic substrate assay (CSA) have been reported for FIX mutations that are associated with nonsevere hemophilia B and may hinder accurate identification of patients for therapy.
2. Use of OSA depends on therapy and OSA activator.