Non-thrombotic-, non-inhibitor-associated adverse reactions to coagulation factor concentrates for treatment of patients with hemophilia and von Willebrand’s disease: a systematic review of prospective studies

Knee replacement surgery in a patient with acquired von Willebrand disease: a case study with recommendations for patient management

Introduction and importance

Acquired von Willebrand disease (AvWD) is a rare underdiagnosed bleeding disorder caused by alterations in the levels of the major blood-clotting protein von Willebrand factor (vWF). The clinical and laboratory parameters of AvWD are similar to congenital vWD, but it is found in individuals with no positive family history with no underlying genetic basis. The disease remains multifactorial and incompletely understood. Proposed mechanisms include the development of autoantibodies to vWF, absorption of high molecular weight vWF multimers that impair normal function, shear stress induced vWF cleavage and increased proteolysis.The aetiology of the disease is variable, the most common being hematoproliferation, lymophoproliferation, myeloproliferation and autoimmune and cardiovascular disorders. Consensus and protocols for AvWD patients that require major surgery are currently lacking. Patients with AvWD can experience thrombotic events during surgery as a result of therapeutic interactions with pro-thrombotic risk factors.

Case presentation

Here, the authors report a patient with AvWD requiring a knee prosthesis implantation due to chronic pain, limited range of motion and functional impairment. The patient had a high risk of bleeding during surgery and was at risk of thrombosis due to age and obesity.

Clinical discussion

Perioperative care required a collaborative approach and the management of bleeding. The patient was administered vWF concentrate Willfact lacking Factor VIII to prevent haemorrhage and to minimize the risk of thrombosis.

Conclusion

The treatment was effective and well-tolerated. The authors use this information to provide recommendations for AvWD patients for whom major surgery is indicated.

Current and Emerging Options for the Management of Inherited von Willebrand Disease

Von Willebrand disease (VWD) is the most common inherited bleeding disorder with an estimated prevalence of ~1% and clinically relevant bleeding symptoms in approximately 1:10,000 individuals. VWD is caused by a deficiency and/or defect of von Willebrand factor (VWF). The most common symptoms are mucocutaneous bleeding, hematomas, and bleeding after trauma or surgery. For decades, treatment to prevent or treat bleeding has consisted of desmopressin in milder cases and of replacement therapy with plasma-derived concentrates containing VWF and Factor VIII (FVIII) in more severe cases. Both are usually combined with supportive therapy, e.g. antifibrinolytic agents, and maximal hemostatic measures. Several developments such as the first recombinant VWF concentrate, which has been recently licensed for VWD, will make a more "personalized" approach to VWD management possible. As research on new treatment strategies for established therapies, such as population pharmacokinetic-guided dosing of clotting factor concentrates, and novel treatment modalities such as aptamers and gene therapy are ongoing, it is likely that the horizon to tailor therapy to the individual patients' needs will be extended, thus, further improving the already high standard of care in VWD in most high-resource countries.

The current state of adverse event reporting in hemophilia

INTRODUCTION

Replacement of the missing clotting factor is the mainstay of hemophilia treatment. Whilst historically many hemophilia patients were infected with blood-borne viruses transmitted via plasma-derived products, nowadays the formation of alloantibodies against the missing clotting factor is the main adverse event of treatment. Areas covered: This paper provides an overview of the current national and international adverse event reporting systems, what these surveillance schemes taught us about side effects of the products presently in use, and elaborates on how to adapt these systems to the challenges we face with the changing treatment landscape. Expert commentary: Treatment of inherited bleeding disorders was accompanied by severe complications in the past, resulting in major morbidity and mortality. Current products are much safer, but still require monitoring via efficient safety surveillance systems. Adverse events are reported in national and international systems. With many new products entering the market, as well as non-factor replacement therapies, new safety issues may arise. It is important to identify potential adverse events early by making surveillance systems suitable to pick up unknown or unexpected effects, and to recognize and communicate patterns of adverse events rapidly.

Safety surveillance in haemophilia and allied disorders

The introduction of clotting factor concentrates has transformed the lives of persons with inherited bleeding disorders. With the use of prophylactic treatment, it is now possible to prevent bleeding in these individuals. The early concentrates were contaminated with the HIV and hepatitis C viruses (HCV) and resulted in major morbidity and mortality in the recipients. Current products are much safer, especially in terms of infectious agents, but other adverse events such as alloantibodies (inhibitors), allergic reactions and thrombotic risks remain of concern. Approximately 30% of previously untreated patients with severe haemophilia A develop inhibitors, making this the most important issue in haemophilia care today. Recently, it was suggested that one of the most commonly used concentrates was associated with a higher inhibitor risk, but this was not supported by the evidence from all studies. Good safety surveillance systems are essential for all diseases and products but are particularly so in the group of individuals with inherited bleeding disorders treated with clotting factor concentrates who have suffered disproportionately from the adverse effects of their treatment. National and multinational systems are now in place to allow reporting of adverse events in patients with inherited bleeding disorders. All clinicians treating individuals with inherited bleeding disorders should prospectively report adverse events to treatment even if they are believed to be common and well recognized.

Scratching the surface of allergic transfusion reactions

Allergic transfusion reactions (ATRs) are a spectrum of hypersensitivity reactions that are the most common adverse reaction to platelets and plasma, occurring in up to 2% of transfusions. Despite the ubiquity of these reactions, little is known about their mechanism. In a small subset of severe reactions, specific antibody has been implicated as causal, although this mechanism does not explain all ATRs. Evidence suggests that donor, product, and recipient factors are involved, and it is possible that many ATRs are multifactorial. Further understanding of the mechanisms of ATRs is necessary so that rationally designed and cost-effective prevention measures can be developed.