Challenges in the classification of von Willebrand disease with a limited test panel: An experience from an upcoming hemostasis laboratory in southern India

Abstract

Objectives: The diagnosis and classification of von Willebrand disease (VWD) is an intricate process requiring multiple hemostatic tests. Cutoff values of the tests vary with the subtype. Sometimes, all the tests are not available. This study was done to analyze the clinical and coagulation profile of VWD diagnosed and broadly classified based on a simplified algorithm. Material and Methods: This was a cross-sectional study done over 6 years. After screening tests, a simplified algorithm taking cutoff for various tests based on updated guidelines using the primary panel of von Willebrand factor antigen assay (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), and Factor VIII:C was used. Multimer assay was done in a few cases. Data were compiled using summary statistics. Results: Forty patients fitted the diagnosis of VWD: Type 3 in 13 (32.5%), Type 2N (likely) in 8 (20%), Type 2 (not further categorized) in 9 (22.5%), and VWD, not further categorized in 10 (25%). The mean age was in the second or third decade with female predominance. Diagnosis of Type 3 was relatively straightforward due to markedly deranged parameters. Type 2N was provisionally diagnosed based on bleeding pattern and markedly reduced Factor VIII:C; further, subtyping of Type 2 and categorization of some cases was not possible due to non-availability of some tests. Conclusion: VWF:Ag assay, VWF:RCo, and Factor VIII:C form the cornerstone for diagnosing major VWD types. The under-representation of milder phenotypes and a greater proportion of severe VWD subtypes observed is likely due to hospital referral bias and may not represent population prevalence.