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The factor VIII inhibitor assays can be standardized: results of a workshop
Author(s) -
VERBRUGGEN B.,
DARDIKH M.,
POLENEWEN R.,
VAN DUREN C.,
MEIJER P.
Publication year - 2011
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2011.04479.x
Subject(s) - false positive paradox , medicine , external quality assessment , coefficient of variation , chromatography , chemistry , pathology , statistics , mathematics
Summary. Background: The Bethesda and the Nijmegen assays are commonly used for the measurement of inhibitor levels in hemophilia A patients. Despite test innovations, the between‐laboratory coefficient of variation (CVb) of factor VIII inhibitor test data in external quality surveys remains very high (40–60%) with a high degree of false‐negative and false‐positive results resulting in undesired effects on treatment. Objectives: Organization of a workshop in order to address the causes of this phenomenon and to suggest ways to improve the assays. Methods: Fifteen laboratories showing a high CVb in regular surveys and using a variety of methods participated in the wet workshop, which included four different sessions where variables probably contributing to the high CVb (e.g. use of [non‐]buffered plasma, FVIII‐deficient plasma, sample dilution and APTT reagents) were investigated. Results: The CVb varied from 30% to 70% in the first session of the workshop when the participants used their own test settings and reagents. The use of buffered normal pooled plasma and FVIII‐deficient plasma as a reference sample by all participants did not significantly alter the CVb (35–50%) but decreased the number of false positives. However, the use of buffered pooled plasma in combination with standardized sample dilution procedures by all participants showed a significant improvement (CVb, 10–20%). Conclusions: These results may contribute to improvement of FVIII inhibitor testing. However, improved inter‐laboratory comparison of factor VIII inhibitor assay results can only be reached when further local standardization is implemented.