Whole blood ristocetin-induced platelet impedance aggregometry does not reflect clinical severity in patients with type 1 von Willebrand disease

BACKGROUND: The haemorrhagic phenotype in patients with von Willebrand disease (VWD) is heterogeneous, and assays of von Willebrand factor ristocetin cofactor activity (VWF:RCo) do not always reflect clinical severity, especially in those individuals classed as type 1 VWD. Recent studies have shown that whole blood ristocetin-induced platelet agglutination (WB-RIPA) using an easy-to-use analyzer, Multiplate® platelet impedance technique, could be informative as a diagnostic test in VWD, although inconsistencies were evident in patients with the type 1 disorder, possibly associated with clinical symptoms. AIM: To investigate the relationship between WB-RIPA, bleeding scores (BS) and VWF-related measurements in type 1 VWD. METHODS: WB-RIPA assay using the Multiplate® was performed using whole blood from 55 patients with type 1 VWD. BS was determined using a standardized questionnaire. RESULTS: WB-RIPA values were significantly lower in type 1 VWD than in healthy controls (P  70 U did not seem to have an abnormal bleeding tendency, but low levels of WB-RIPA did not correlate with BS. CONCLUSION: WB-RIPA did not reflect clinical severity in type 1 VWD patients.