A collaborative trial has been carried out under the auspices of the International
Committee on Thrombosis and Haemostasis to compare the Bethesda and New Oxford methods
of antibody assay. It was found that errors between laboratories were much greater
than those within laboratories and each laboratory had a bias whereby it always rated
samples high or low with respect to the other laboratories. However there was excellent
agreement in the order in which laboratories ranked antibody samples and if a standard
antibody sample could be provided there would be a significant improvement in numerical
agreement between laboratories. On average, for this exercise, a result for a given
sample in Bethesda units was 1.21 times the result in New Oxford units although it
must be stressed that this ratio could vary from sample to sample.
Key words
Factor VIII - Factor VIII antibodies - Bethesda method -New Oxford method - Comparison
of antibody methods
