Advances in the diagnosis and management of von Willebrand disease

Response to low-dose desmopressin by a subcutaneous route in children with type 1 von Willebrand disease

OBJECTIVE

The primary objective of this study was to determine responses to low-dose desmopressin (DDAVP) by a subcutaneous route in children with type 1 VWD.

METHODS

This study analyzed responses to low doses of DDAVP administered by a subcutaneous route to 14 children between the ages of 3 and 16 with type 1 VWD and a personal and familial history of bleeding. At 0 (baseline) and 1 hour (initial response) after the subcutaneous injection of DDAVP, the vital signs were assessed and blood samples were obtained for VWD panel determinations (VWF:Ag, VWF:RCo, FVIII:C levels, and Col/Epi, Col/ADP). At 4 hours (sustained response), only Col/Epi and Col/ADP were assessed.

RESULTS

The DDAVP mean (min-max range, μg/kg) based on the patient's weight was 0.15 (0.12-0.18). Laboratory values mean (min-max range in U/dl) baseline for VWF:RCo, VWF:Ag, and FVIII:C were 28 (20-36), 34 (25-42), and 40 (29-48), respectively. After a subcutaneous administration, the laboratory values mean (min-max range in U/dl(-1)) achieved for 1 hour for VWF:RCo, VWF:Ag, and FVIII:C were 109 (72-144), 132 (88-166), and 151 (96-198), respectively. PFA 100(®) CT (Col/Epi <134 seconds and Col/ADP <110 seconds) returned to normal values at 1 and 4 hours after a subcutaneous administration.

CONCLUSION

Subcutaneous low-dose DDAVP therapy is at least effective as 0.3 µg/kg intravenous therapy for children with type 1 VWD. This study shows that a wider use of DDAVP should be promoted, especially in developing countries.

Von Willebrand factor predicts major bleeding and mortality during oral anticoagulant treatment

AIMS

Oral anticoagulation (OAC), predominantly with warfarin, is an effective treatment to prevent thromboembolic events. Serious bleeding is a frequent and feared treatment complication. In this longitudinal cohort study of OAC-treated patients, we aimed to evaluate the relationship between von Willebrand factor (VWF) levels and risk of bleeding complications, cardiovascular mortality and all-cause mortality.

METHODS AND RESULTS

A total of 719 patients receiving warfarin treatment were observed for a mean duration of 4.2 years. All bleeding complications causing hospitalization were registered and classified into clinically relevant bleeding (CRB) and major bleeding. Ischaemic stroke, peripheral arterial embolism, myocardial infarction, and death were also recorded. We identified 113 cases of CRB and 73 of major bleeding. In total, 161 deaths occurred during follow-up with cardiovascular disease identified as the cause of death in 110 patients. Patients in the highest tertile of VWF had a significantly increased risk of bleeding complications: hazard ratio (HR) 2.53 (95% CI 1.41-4.56) for major bleeding and HR 2.19 (95% CI 1.38-3.48) for CRB. VWF, expressed either in tertiles or as a continuous variable, showed a significant association with cardiovascular mortality (HR 1.68, 95% CI 1.40-2.01) and all-cause mortality (HR 1.77, 95% CI 1.52-2.05). In multivariate Cox regression analysis, the findings remained significant after adjusting for age, high-sensitivity C-reactive protein and creatinine.

CONCLUSIONS

Patients with high levels of VWF had an increased risk of bleeding complications, cardiovascular mortality and all-cause mortality during OAC treatment. Our findings imply that the use of VWF as a risk marker for thromboembolic events is complicated by the association of VWF with bleeding complications.