Abstract Number: PB0594
Meeting: ISTH 2020 Congress
Background: Factor VIII (FVIII) measurement is important in the current era of evolving FVIII gene therapy in which a number of studies have shown discrepancy between the one-stage and chromogenic FVIII assays. There is a paucity of studies comparing the two assays.
Aims: To compare the one-stage clot-based and chromogenic assays in the measurement of FVIII in blood sample from a diverse spectrum of hematological conditions in a single tertiary academic centre.
Methods: This is a single centre retrospective study conducted at Sultan Qaboos University Hospital (SQUH). FVIII measurement at the SQUH requested from March 2009 to March 2018 was performed with both assays. Paired FVIII results were compared using Bland-Altman analyses and mostly of small sample size.
Results: A total of 2113 samples had both assays performed. The median age of all patients was 26 years (IQR: 17-37). The commonest indications of testing were recurrent pregnancy loss (7.8%), sickle cell disease (4.7%), hemophilia A (2.8%). The remaining (84.7%) included venous thromboembolism, von Willebrand disease, thalassemia, myeloproliferative neoplasms and others. The median FVIII level by one-stage clot-based and chromogenic assays were 1.17 IU/mL (IQR: 0.8 – 1.6) and 1.2 IU/mL (IQR: 0.9 – 1.6) respectively. Bland-Altman analyses showed excellent agreement with a mean difference of 0.02 IU/mL. The upper and lower agreement boundaries were – 0.53 IU/mL and 0.49 IU/mL respectively. Visually, the points of difference were closer to the mean difference when the mean FVIII level was low. High baseline FVIII level and the diagnosis predicted the disagreement between the two assays (P< 0.001). Positive ANA and FVIII inhibitor had no impact on the disagreement (P of 0.2 and 0.7 respectively).
Conclusions: In this cohort of diverse hematological conditions, one-stage clot-based and chromogenic FVIII assays showed excellent agreement for measuring FVIII activity level especially in patients with low baseline FVIII level.
To cite this abstract in AMA style:
Al Buraidi R, Al-Khabori M, Al Falahi K, Al Baloushi B, Al-Rawahi B, Mahlangu J, Pathare A. Comparison of the One-Stage Clot-Based and Chromogenic Factor VIII Activity Measurement [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/comparison-of-the-one-stage-clot-based-and-chromogenic-factor-viii-activity-measurement/. Accessed September 24, 2023.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/comparison-of-the-one-stage-clot-based-and-chromogenic-factor-viii-activity-measurement/