A detailed comparison of the performance of the standard versus the Nijmegen modification of the Bethesda assay in detecting Factor VIII:C inhibitors in the haemophilia A population of Canada

Alan R. Giles, Bert Verbruggen, Georges E. Rivard, Jerome Teitel, Irwin Walker, Gerry Growe, Man Chiu Poon, John Wu, Robert Card, Kaiser Ali, Sara Israels, Morel Rubinger, Jordan Herst, Kulwant Gill, Martin Inwood, Patricia J. McCusker, Mohan Pai, Bernadette Garvey, Victor Blanchette, Alan GilesDavid Lillicrap, Mariana Silva, Jeanne Drouin, Koon Hung Luke, Mason Bond, Michele David, Georges Rivard, Jean St-Louis, Mariette Lepine-Martin, Christine Demers, Francois Jobin, Marie Frances Scully, Sean Dolan, Sheldon Rubin, Dorothy Barnard, Sue Robinson, Elizabeth Ross, Lawrence Jardine

Research output: Contribution to journalArticlepeer-review

141 Citations (Scopus)

Abstract

The Bethesda assay is widely used to monitor the development and progress of Factor VIII:C inhibitors. Factor VIII stability in the substrate plasma (normal pool) is compromised by pH shift and reduction in protein concentration. Preliminary study, by Verbruggen and colleagues (8), suggested a reduction in spuriously positive assay results may result from buffering the normal pool plasma substrate with imidazole to pH 7.4 and substituting Factor VIII deficient plasma for imidazole buffer in the control incubation mix. These laboratory findings have now been confirmed by the performance of both the standard and the modified Bethesda assays in parallel on 877 patient samples screened during the Factor VIII:C Inhibitor Surveillance Program instituted following the conversion of all Canadian haemophilia A patients to recombinant Factor VIII. Although this study does not address the question of the clinical significance of spurious positive assays, these laboratory findings do support the conclusions of Verbruggen and the modified assay has recently been endorsed by the Factor VIII/IX Subcommittee of the SSC.

Original languageEnglish
Pages (from-to)872-875
Number of pages4
JournalThrombosis and Haemostasis
Volume79
Issue number4
DOIs
Publication statusPublished - Apr 1998

ASJC Scopus Subject Areas

  • Hematology

PubMed: MeSH publication types

  • Comparative Study
  • Journal Article
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

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