Von Willebrand Disease (VWD)
Part 3: VWF Activity Assay

Summary of External Quality Assessment of VWF:RCo

June 2011

These problems are invincible in multiple US and international external quality assurance programs. As summarized in this table, this VWF ristocetin cofactor activity assay has poor precision among participating laboratories in US, UK, Australia and non-Western countries.

< Previous Slide

External Quality Assessment Summary

Next Slide >

 

Jump to section:

• Introduction
• Objectives
• History of VWF Ristocetin Cofactor Activity (VWF:RCo) Assay
• Problems with VWF:RCo Assay
• Summary of External Quality Assessment of VWF:RCo
• von Willebrand Disease(VWD) Diagnostic Error Rates Due to Erroneous VWF:RCo Results⁵
• VWF:RCo/Ag Ratio is Insensitive for Aquired von Willebrand Abnormalities (AVWA)
• VWF:RCo is Inadequate for Detecting AVW Abnormality
• The New Automated VWF Activity by Latex-Immunoturbidity Assay (VWF:Lx)
• VWF Activity Assay by an A1 Domain Conformation-Sensitive Antibody⁶
• Performance Characteristics of VWF:Lx
• VWF:Lx and VWF:RCo Method Comparison
• VWF:Lx and VWF:RCo Bias Analysis
• Sample Categorization
• Comparison of VWF:Lx/Ag and VWF:RCo/Ag Ratios
• VWF:Lx and VWF:RCo Errors
• Severe Type 1 vs 2M⁷
• VWF:Lx and RCo Errors
• VWF:Lx/Ag is Sensitive to AVWA with Subtle Loss of Highest HMWM
• ROC Analysis of VWF:Lx/Ag and VWF:RCo/Ag for Detecting AVWA with Loss of HMWMs
• VWF:Lx/Ag vs VWF:RCo/Ag Ratios
• VWF Laboratory Testing Strategy
• Sensitivity and Specificity of the Screening Panel
• von Willebrand Disease Profile
• von Willebrand Disease Profile
• von Willebrand Disease Profile
• von Willebrand Disease Profile
• Limitations of VWF:Lx
• Summary
• References
• Questions?