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Analytical variation in factor VIII one-stage and chromogenic assays: Experiences from the ECAT external quality assessment programme.

Authors :
van Moort I
Meijer P
Priem-Visser D
van Gammeren AJ
Péquériaux NCV
Leebeek FWG
Cnossen MH
de Maat MPM
Source :
Haemophilia : the official journal of the World Federation of Hemophilia [Haemophilia] 2019 Jan; Vol. 25 (1), pp. 162-169. Date of Electronic Publication: 2018 Nov 29.
Publication Year :
2019

Abstract

Background: Both one-stage (OSA) and chromogenic substrate assays (CSA) are used to measure factor VIII (FVIII) activity. Factors explaining analytical variation in FVIII activity levels are still to be completely elucidated.<br />Aim: The aim of this study was to investigate and quantify the analytical variation in OSA and CSA.<br />Methods: Factors determining analytical variation were studied in sixteen lyophilized plasma samples (FVIII activity <0.01-1.94 IU/mL) and distributed by the ECAT surveys. To elucidate the causes of OSA variation, we exchanged deficient plasma between three company set-ups.<br />Results: On average, 206 (range 164-230) laboratories used the OSA to measure FVIII activity and 30 (range 12-51) used CSA. The coefficient of variation of OSA and CSA increased with lower FVIII levels (FVIII <0.05 IU/mL). This resulted in misclassification of a severe haemophilia A sample into a moderate or mild haemophilia A sample in 4/30 (13.3%) of CSA measurements, while this was 37/139 (26.6%) for OSA. OSA measurements performed with reagents and equipment from Werfen showed slightly lower FVIII activity (0.93, IQR 0.88-0.98 IU/mL) compared to measurements with Stago (1.07, IQR 1.02-1.14 IU/mL) and Siemens (1.03, IQR 0.97-1.07 IU/mL). Part of this difference is explained by the value of the calibrator. For CSA, the measured FVIII levels were similar using the different kits.<br />Conclusions: In the lower range (<0.05 IU/mL), analytical variation of FVIII measurements is high in both OSA and CSA measurements. The variation in FVIII activity levels was partly explained by specific manufacturers. Further standardization of FVIII measurements and understanding of analytical variation is required.<br /> (© 2018 The Authors. Haemophilia Published by John Wiley & Sons Ltd.)

Details

Language :
English
ISSN :
1365-2516
Volume :
25
Issue :
1
Database :
MEDLINE
Journal :
Haemophilia : the official journal of the World Federation of Hemophilia
Publication Type :
Academic Journal
Accession number :
30488994
Full Text :
https://doi.org/10.1111/hae.13643