REAL-LIFE DATA OF CONSTITUTIONAL VON WILLEBRAND DISEASE IN WESTERN FRANCE (HOPSCOTcH-WILL)

von Willebrand Disease (vWD) represents the most common autosomal inherited bleeding disorders with a prevalence up to 1%; nevertheless the clinical relevant patients represent only 0.01% of the population.

vWD is caused by a deficiency and/or abnormality of von Willebrand factor (VWF), inhibiting a satisfactory hemostasis. vWD is usually classified into three main types according to quantitative (Types 1 and 3) or qualitative (Types 2A, 2B, 2M, 2N) deficiencies. Type 3 patients have the highest bleeding risk, type 2 patients are intermediate and type 1 patients have the lowest bleeding risk. Beyond the typology, VWF levels, and therefore the hemorrhagic exposition, are also notably influenced by physiological (age, exercise, pregnancy, gene mutations) or pathological (inflammation and cancer) variables. Furthermore, blood group plays a major role in plasma VWF levels; in fact they are 25%-35% lower in type-0 individuals than in non-0. As a result, the clinical and biological identification of vWD can be extremely challenging and may lead to a delay in the diagnosis.

In vWD, the clinical manifestations are essentially mucosal bleeding symptoms. Epistaxis, menorrhagia, easy bruising, gingival bleeding are flagrant manifestations of the disease and, despite the mostly small somatic impact in the majority of patients; they may significantly affect the quality of life. Nevertheless, severe affected patients may face upper consequences: gastrointestinal (GI) bleeding may be particularly frequent and difficult to manage, and they are as well at high risk to develop major and life-threatening bleeds after surgical procedures, even after minor ones such as tooth extraction.

To guarantee the best medical care management, VWD patients are followed in specialized rare disease centers, both for the ambulatory follow-up and the hospitalizations \& outpatient aftercare. These hospital structures are the only ones authorized to prescribe and dispense in- \& outpatients' substitutive treatments.

Indeed, the optimal effective treatment of the disorder is the replacement of VWF by using VWF concentrate obtained by fractionation of human plasma; in emergency, recombinant or plasma-derived factor VIII (FVIII) can be added to the VWF. In case of history of inhibitors, high dose of FVIII or by-passing agents can also be used. The current treatment for vWD involves intravenous injections of VWF that are either given on demand in response to a bleeding event or as a prophylactic therapy that is administered 2 to 4 times a week. Numerous studies have shown the efficacy of prophylactic therapy in severe patients, but the investigators lack data about surgery procedures and perioperative management. Moreover, regardless of the small amounts of patients, those treatments remain quite costly and may represent an economic burden for the Assurance Health System.

Due to the future availability of the first recombinant VWF, the investigators need a better understanding of the current French practices. The lack of literature on the topic is undeniably blatant and the few relevant papers concerned specific pd-VWF concentrates; no RWD publication has been identified for the specific French cohort. The heterogeneity of VWD concentrates brands and VWD types make the development of personalized care quite difficult in this context and more information is needed, especially for the peri-operative treatment. The economic evaluations usually focus on prophylaxis treatments or a specific concentrate, neglecting a significant percentage of patients.

The objective of our 4-years retrospective study HOPSCOTcH-WILL is to provide an accurate and detailed account of current vWD therapeutic management by collecting real-life data on hemorrhagic treated events in 5 Western French HTC (Angers, Brest, Le Mans, Nantes \& Rennes). The data will be retrospectively recorded during 48 months from 2015 to 2018 for patients followed in the 5 HTC involved in the study. A focus will be done on GI episodes and surgeries which are the most at risk hemorrhagic events in vWD.

HOPSCOTcH-WILL could be considered as reliable photography of Western French HTC at a particular time. Therefore, and especially with the launch of a new recombinant VWF, it is particularly important to get a clear state-of-the-art and to assess the economic impact for the French Health System.