Comparative Study between One Stage Clot Based assay and Chromogenic Substrate Assay for Monitoring Factor VIII Activity in Hemophilia A Patients

Abstract

can be measured by the one-stage clotting assay (OSA). OSA is still the most widely used, but some limitations are led to misdiagnosis. Therefore, the chromogenic substrate assay (CSA) which is used to measure a color intensity produced, is directly proportional to the amount of FXa, subsequently turned to the FVIII activity. This study aimed to compare the FVIII levels between OSA and CSA methods in patient’s plasma, before and after FVIII therapy (N=18). 17 patients for plasma-derived factor VII (pdFVIII) therapy and 1 patient for Emicizumab therapy were recruited in this study. We reported the FVIII levels, both before and after pdFVIII therapy, from two methods significantly correlated (P-value < 0.0001). Briefly, both methods were a suitable for follow-up the FVIII level in pdFVIII plasma, but Emicizumab plasma showed the lower detection limit in both methods that were related to previous reports. In case of hemophilia A patient with inhibitor who treated with Emicizumab, Factor VIII inhibitors were determined by using a special chromogenic bethesda assay (CBA) method. We suggest the Emicizumab therapy’s patient should be used FVIII inhibitor by CBA for a follow-up method.