Conference App Publication Indian Ocean Rim Laboratory Haematology Congress 2014

Automated chemiluminescence assay for von Willebrand factor antigen and ristocetin cofactor (#42)

Sue Rodgers 1 , Elizabeth Duncan 1 , Ray Dauer 2 , Katherine Cummins 2 , Vaahini James 2 , Heather Aumann 2 , Margaret Collecutt 2 , Susan Morgan 2
  1. Haemostasis Unit, Haematology Division, IMVS, Adelaide, SA, Australia
  2. Haematology Laboratory, The Alfred Hospital, Melbourne, VIC, Australia

Aim: The aim of this study was to compare the ACL AcuStar chemiluminescence assay for VWF:Ag and VWF:RCo with standard testing using the STAGO STA-R Evolution using latex immunoassay for VWF:Ag and platelet agglutination based VWF:RCo assay.

Method: A cohort of 51 samples of both normal and von Willebrand disease patients. There were nine type 2M, four type 2B and two type 2A included in the cohort.

Results: There was good correlation between VWF:Ag assay with an r value of 0.9934 (95% CI 0.9885 to 0.9963) and 0.9547 (95% CI 0.9217 to 0.9740) for the VWF:RCo. There was a negative bias for the AcuStar compared to the STAGO STA-R for both the VWF:Ag and VWF:RCo with the STAGO results being higher by 10.8% and 14.4% respectively. Importantly, all of the type 2 patients were identified by the AcuStar method, with the ratio of VWF:RCo to VWF:Ag < 0.5 for all.

Conclusion: AcuStar VWF:Ag and VWF:RCo compared well with our conventional testing systems. There was greater discordance with the VWF:RCo testing compared to the VWF:Ag and this may be due to a difference in technology. The negative bias suggests that the reference range for the AcuStar is lower and would need to be established for this platform.