PB0818 - Response rate of different DDAVP dosing in Haemophilia A and von Willebrand disease

Background: DDAVP is used in Haemophilia A and Von Willebrand disease (vWD) for haemostasis. Various DDAVP dosing regimens are used for the DDAVP challenge. The original dose suggested by Mannucci et al was 0.3 mcg/kg intravenously (IV), while others use 0.2mcg/kg IV dosing. Some national guidelines recommend a capped dose of 20 mcg IV or SC, while others have used a capped dose of 15 mcg SC.

Aims: The objective is to compare the response rate, and safety profile between 0.2mcg/kg and 0.3mcg/kg dosing during a DDAVP challenge.

Methods: This is a retrospective analysis using prospective data from the Australian Bleeding Disorders Registry (ABDR) from 1998 to 2017. Patients with Haemophilia A or vWD undergoing a DDAVP challenge were included. Response rate to DDAVP was defined as a greater than 50IU/dL increase in FVIII (for haemophilia A), and greater than 50IU/dL increase in FVIII and VWF:RCoF for patients with vWD. Changes in factor VIII, vWFAg and RiCoF were also obtained. Any adverse effects and changes in sodium levels were also recorded. These outcomes were then compared between individuals who received a < 0.25mcg/kg dosing of DDAVP compared with those receiving a greater dose (to accommodate rounding).

Results: 128 patients were included. 79 out of 85 patients (92.9%) who received a dose of less than 0.25mcg/kg were responsive, compared to 40 out of 43 patients (93.0%) receiving a dose greater than 0.25mcg/kg. Adverse events (predominantly facial flushing) were similar between groups; 10 out of 85 patients (11.7%) in the lower dosing group compared to 4 out of 43 (9.3%) in the higher dosing group. Data for incidence of hyponatraemia is still pending.

Conclusion(s): Response rates and adverse events were similar between the 0.2mcg/kg and 0.3mcg/kg DDAVP dosing groups, suggesting lower doses are equivalent in achieving the same response in patients with Haemophilia and vWD.