Desmopressin therapy to assist the functional identification and characterisation of von Willebrand disease: differential utility from combining two (VWF:CB and VWF:RCo) von Willebrand factor activity assays?

ABSTRACT

We performed a retrospective audit of desmopressin (DDAVP) usage to assist in the functional characterisation of von Willebrand disease (VWD). Data was evaluated for 208 patients, comprising those with VWD (Type 1 [n=160], Type 2A [n=19], Type 2M [n=10]), plus 19 individuals with haemophilia or carriers of haemophilia. Laboratory testing comprised pre- and post-DDAVP evaluation of factor VIII (FVIIIC), von Willebrand factor (VWF) antigen (VWFAg), VWF ristocetin cofactor (VWFRCo) activity, VWF collagen binding (VWFCB) activity, and in one laboratory an alternate VWF activity assay. In brief, combined usage of VWFRCo and VWFCB appears to provide improved functional characterisation and/or 'classification' of VWD types, in particular better differentiation of Type 2A and 2M VWD, and clearer validation of a Type 1 VWD diagnosis. Thus, (i) Type 1 VWD displayed generally good absolute and relative rises in all test parameters, although relative rises were greatest for FVIIIC and VWFCB, and CB/Ag ratio increases overshadowed those for RCo/Ag; (ii) Type 2A VWD patients showed good absolute and relative rises in both FVIIIC and VWFAg, but poor absolute rises in both VWFCB and VWFRCo; although small rises in both CB/Ag and RCo/Ag were also observed, both ratios tended to remain below 0.7; (iii) finally, Type 2 M VWD patients generally showed good absolute and relative rises in FVIIIC, VWFAg and VWFCB, but a poor absolute and relative rise in VWFRCo; thus, there were good rises in CB/Ag ratios but little change in RCo/Ag, which tended to remain below 0.7. Future multi-centre prospective investigations are warranted to validate these findings and to investigate their therapeutic implications.