Immunoadsorption may provide a cost-effective approach to management of patients with inhibitors to FVIII

Immunoadsorption for the Treatment of Acquired Hemophilia: New Observational Data, Systematic Review, and Meta-Analysis

The treatment of patients with acquired hemophilia is challenging due to life-threatening hemorrhages, delayed response, and adverse effects to immunosuppressive agents. Even though immunoadsorption (IA) rapidly removes autoantibodies against factor VIII, this intervention's effectiveness is still a matter of debate. We aimed to study important outcomes of IA as adjunctive treatment in patients with acquired hemophilia. We performed comprehensive literature searches in MEDLINE and EMBASE databases. Clinical and laboratory data of all patients treated in our institution were additionally included. Literature searching yielded 498 records, of which 10 studies describing 106 patients were finally included. The number of patients varied from 1 to 65, and patients' ages ranged between 14 and 89. Treatment criteria in most patients were (1) failed response to immunosuppressive treatment alone, and/or (2) uncontrollable bleeding episodes, and/or (3) high inhibitor titer. Methodological quality was moderate. The number of IA sessions varied from 1 to 24. Within our institution, 12 patients have been treated since 2002; median age was 76 years (range 34-86); median titer of factor VIII inhibitor was 20 Bethesda units (range 3-214). Pooled estimates, modeling a random-effect binominal distribution incorporating the Freeman-Tukey double arcsine transformation, were 86% in case of factor VIII recovery (95% confidence interval 76%-94%), 95% for reduction of factor VIII inhibitor (83%, 100%), and 7% in case of death (0%, 18%). Our data suggest that IA might be a beneficial adjunctive treatment in patients with high-risk acquired hemophilia, but future studies shall confirm this observation.

Use of Cellular and Plasma Apheresis in the Critically Ill Patient: Part II: Clinical Indications and Applications

Apheresis is the process of separating the blood and removing or manipulating a cellular or plasma component for therapeutic benefit. Such procedures may be indicated in the critical care setting as primary or adjunctive therapy for certain hematologic, neurologic, renal, and autoimmune/rheumatologic disorders. In part I of this series, the technical aspects of apheresis were described and the physiologic rationale and clinical considerations were discussed. This review highlights the pathophysiologic basis, specific clinical indications, and treatment parameters for disorders that more commonly require management in the intensive care unit. The choice of plasma or cellular apheresis in these cases is guided by wellaccepted, evidence-based clinical treatment guidelines. For some disorders, such as liver failure, severe sepsis, and multiple-organ dysfunction syndrome, apheresis treatment approaches remain experimental. Ongoing studies are investigating the potential utility of conventional plasma exchange, ex vivo plasma manipulation, and newer technologies for these and other disorders in severely ill patients.

Successful immunoadsorption of life-threatening bleeding in factor VIII inhibitor disease, but no long-term remission with anti-CD20 treatment

A 62-year-old man and a 64-year-old woman presented to our institution with acquired haemophilia A. They both developed life-threatening bleeding. Immunoadsorption using protein A columns was used to rapidly lower factor VIII inhibitor levels. Immunosuppression with steroids and the anti-CD20 antibody, rituximab, was instituted. Yet their effects were either partial or complicated by an early relapse. Repetitive cyclophosphamide administration led to a sustained immunological response. While immunoadsorption appears effective and safe to lower factor VIII inhibitor levels, it seems that further preferably randomised controlled trials are needed to establish the value of rituximab versus the standard immunosuppressive regime comprising cyclophosphamide.

Immune tolerance induction for treating inhibitors in people with congenital haemophilia A or B

BACKGROUND

The occurrence of factor inhibitory antibodies, or inhibitors, is a significant complication in the care of individuals with congenital haemophilia A or B. Currently, immune tolerance induction is the only known intervention to successfully eradicate inhibitors. However, ideal dosing regimens, and the comparative safety and efficacy of different immune tolerance induction regimens have not yet been established.

OBJECTIVES

The objective of this review was to assess the effects of immune tolerance induction (different protocols of this therapy versus each other, or versus only bypassing agents) for treating inhibitors in people with congenital haemophilia A or B.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Coagulopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched: MEDLINE (from 1946 to 15 July 2013); Embase (from 1980 to 15 July 2013) via the OVID platform; CINAHL (from conception to 15 July 2013); and ClinicalTrials.gov (most recent search: 15 July 2013). We also searched the reference lists of relevant articles and reviews.

SELECTION CRITERIA

Randomised controlled trials comparing either different immune tolerance induction regimens or immune tolerance induction versus only bypassing therapy for the eradication of factor inhibitory antibodies in patients with congenital haemophilia A or B.

DATA COLLECTION AND ANALYSIS

Two review authors independently completed data collection, extraction and assessment of the risk of bias of trials.

MAIN RESULTS

One methodologically sound randomised controlled trial met the inclusion criteria and was included in the review. One further randomised controlled trial has been recently stopped, but it has not yet been reported.The included multinational trial randomised 115 paediatric participants with severe haemophilia A and high-responding inhibitors, for whom this was the first attempt at immune tolerance induction, to receive either a low dose (50 IU/kg of factor VIII concentrate three times per week) or a high dose (200 IU/kg of factor VIII daily). Although, there was no statistically significant difference in the success of immune tolerance induction between treatment arms, the confidence intervals were too wide to infer no effect: 24 out of 58 participants (46.6%) in the low-dose group and 22 out of 57 (38.6%) in the high-dose group experiencing full tolerance, risk ratio 1.07 (95% CI 0.68 to 1.68) (moderate quality evidence). The rate of infection was not statistically different between groups, but again confidence intervals were too wide. Of those patients who had a central venous catheter device, 19 out of 47 participants (40.4%) in the low-dose arm had 69 infections, and 22 out of 52 participants (42.3%) in the high-dose arm had 55 infections, risk ratio 0.96 (95% CI 0.60 to 1.53) (moderate quality evidence). However, participants in the low-dose immune tolerance induction group experienced significantly more bleeding episodes (50 out of 58 participants (86.2%) experienced one or more bleeding events) than those in the high-dose group (36 out of 57 participants (63.1%) experienced one or more bleeding events), risk ratio 1.36 (95% CI 1.09 to 1.71) (low quality evidence). One factor VIII reaction, one incidence of trauma and 13 incidences of needing to insert or remove the catheter were reported as trial-related serious adverse events; however, the treatment group where these events occurred was not specified. No incidence of nephrotic syndrome was reported.

AUTHORS' CONCLUSIONS

We did not find any randomised controlled trial-based comparison of immune tolerance induction with alternate treatment schemes (i.e. bypassing agents for bleeding only). In a single randomised trial, there were no significant differences in the immune tolerance induction success rate between different dosing regimens, which may have been due to imprecision of the estimate. There is low-quality evidence to suggest that high-dose immune tolerance induction may induce tolerance more quickly which is associated with fewer bleeding complications. The choice of immune tolerance induction regimen should be considered individually for each case, until further research provides additional evidence.

An Acquired Factor VIII Inhibitor in a Patient with HIV and HCV: A Case Presentation and Literature Review

Introduction. Despite its low incidence, acquired factor VIII inhibitor is the most common autoantibody affecting the clotting cascade. The exact mechanism of acquisition remains unclear, but postpartum patients, those with autoimmune conditions or malignancies, and those with exposure to particular drugs appear most susceptible. There have been several case reports describing acquired FVIII inhibitors in patients receiving interferon alpha for HCV treatment and in patients being treated for HIV. To our knowledge, this is the first case of a patient with HCV and HIV who was not actively receiving treatment for either condition. Case Presentation. A 57-year-old Caucasian male with a history of HIV and HCV was admitted to our hospital for a several day history of progressively worsening right thigh bruising and generalized weakness. CTA of the abdominal arteries revealed large bilateral retroperitoneal hematomas. Laboratory studies revealed the presence of a high titer FVIII inhibitor. Conclusion. Our case of a very rare condition highlights the importance of recognizing and understanding the diagnosis of acquired FVIII inhibitor. Laboratory research and clinical data on the role of newer agents are needed in order to better characterize disease pathogenesis, disease associations, genetic markers, and optimal disease management.

Immune Tolerance Therapy in Patients with Acquired Hemophilia

Acquired hemophilia is a rare disorder with an estimated annual incidence of 0.2-1 cases per million individuals. The etiology of the disorder remains obscure, although approximately half of all cases are associated with other underlying conditions. In acquired hemophilia, the severe hemorrhagic diathesis is caused by the development of autoantibodies directed against a clotting factor, most commonly factor VIII. These autoantibodies inhibit normal coagulation and lead to bleeding complications, which can be life-threatening in a high percentage of cases. Prompt diagnosis and appropriate management of the disorder enable effective control; the short- and long-term aims of therapy are to terminate the acute bleed and eliminate or reduce the inhibitor, respectively. Immune tolerance therapy has been shown to successfully eradicate or suppress inhibitors in patients with congenital hemophilia A and may be applicable to patients with acquired hemophilia. Here we present preliminary data on the use of immune tolerance therapy in patients with acquired hemophilia and discuss possible treatment strategies.

Management of acquired haemophilia A

Acquired haemophilia A is an auto-immune disease caused by an inhibitory antibody to factor VIII. The pattern of bleeding varies but patients remain at risk of life threatening bleeding until the inhibitor has been eradicated. The cornerstones of management are; rapid and accurate diagnosis, control of bleeding, investigation for an underlying cause and eradication of the inhibitor by immunosuppression. Patients should always be managed jointly with a specialist centre even if they present without significant bleeding. Despite an extensive literature, few controlled data are available and treatment guidelines are based on expert opinion. To treat bleeds recombinant factor VIIa and activated prothrombin complex concentrate are equally efficacious but both are superior to factor VIII or desmopressin. Immunosuppression should be started as soon as the diagnosis is made. Commonly used regimens are steroids alone or combined with cytotoxic agents. Rituximab is being used more widely but current evidence does not suggest that it improves outcomes or reduces side effects.

Consensus recommendations for the diagnosis and treatment of acquired hemophilia A

BACKGROUND

Acquired hemophilia A (AHA) is a rare bleeding disorder caused by an autoantibody to coagulation factor (F) VIII. It is characterized by soft tissue bleeding in patients without a personal or family history of bleeding. Bleeding is variable, ranging from acute, life-threatening hemorrhage, with 9-22% mortality, to mild bleeding that requires no treatment. AHA usually presents to clinicians without prior experience of the disease, therefore diagnosis is frequently delayed and bleeds under treated.

METHODS

Structured literature searches were used to support expert opinion in the development of recommendations for the management of patients with AHA.

RESULTS

Immediate consultation with a hemophilia center experienced in the management of inhibitors is essential to ensure accurate diagnosis and appropriate treatment. The laboratory finding of prolonged activated partial thromboplastin time with normal prothrombin time is typical of AHA, and the diagnosis should be considered even in the absence of bleeding. The FVIII level and autoantibody titer are not reliable predictors of bleeding risk or response to treatment. Most patients with AHA are elderly; comorbidities and underlying conditions found in 50% of patients often influence the clinical picture. Initial treatment involves the control of acute bleeding with bypassing agents. Immunosuppressive treatment to eradicate the FVIII inhibitor should be started as soon as the diagnosis is confirmed to reduce the time the patient is at risk of bleeding.

CONCLUSIONS

These recommendations aim to increase awareness of this disorder among clinicians in a wide range of specialties and provide practical advice on diagnosis and treatment.

Advances in the understanding of acquired haemophilia A: implications for clinical practice

Acquired haemophilia A is an auto-immune disease caused by an inhibitory antibody to factor VIII. Patients with an acquired factor VIII inhibitor are at risk of life- and limb-threatening bleeding until the inhibitor has been eradicated. Management relies on rapid and accurate diagnosis, control of bleeding episodes, investigation for a precipitating cause and eradication of the inhibitor by immunosuppression. Patients should always be managed jointly with a specialist centre even if they present without overt bleeding. Despite an extensive literature, few controlled data are available and management guidelines are predominantly based on case reports, retrospective cohorts and expert opinion. This paper reviews the current literature on incidence, pathogenesis, diagnosis, haemostatic therapy and inhibitor eradication strategies. Potential future developments are discussed.

International recommendations on the diagnosis and treatment of patients with acquired hemophilia A

Acquired hemophilia A (AHA) is a rare bleeding disorder characterized by autoantibodies directed against circulating coagulation factor (F) VIII. Typically, patients with no prior history of a bleeding disorder present with spontaneous bleeding and an isolated prolonged aPTT. AHA may, however, present without any bleeding symptoms, therefore an isolated prolonged aPTT should always be investigated further irrespective of the clinical findings. Control of acute bleeding is the first priority, and we recommend first-line therapy with bypassing agents such as recombinant activated FVII or activated prothrombin complex concentrate. Once the diagnosis has been achieved, immediate autoantibody eradication to reduce subsequent bleeding risk should be performed. We recommend initial treatment with corticosteroids or combination therapy with corticosteroids and cyclophosphamide and suggest second-line therapy with rituximab if first-line therapy fails or is contraindicated. In contrast to congenital hemophilia, no comparative studies exist to support treatment recommendations for patients with AHA, therefore treatment guidance must rely on the expertise and clinical experience of specialists in the field. The aim of this document is to provide a set of international practice guidelines based on our collective clinical experience in treating patients with AHA and contribute to improved care for this patient group.

Treatment of acquired haemophilia with recombinant activated FVII: a critical appraisal

Acquired haemophilia is a rare bleeding disorder usually caused by the spontaneous formation of inhibitory antibodies to coagulation FVIII. The disease occurs most commonly in the elderly, and although acquired haemophilia may be associated with a variety of underlying conditions, up to 50% of reported cases are idiopathic. Treatment options have traditionally involved human FVIII or FIX replacement therapy (if the inhibitor titre allows), porcine FVIII or the use of activated pro-thrombin complex concentrates. Recombinant activated coagulation FVII (rFVIIa) was available on an emergency and compassionate use basis from 1988 to 1999 at sites in Europe and North America. It has been registered in Europe for use in treating acquired haemophilia since 1996 and has recently been licensed for this indication in the United States. By directly activating FX on the surface of activated platelets at the site of injury (thereby bypassing FVIII and FIX), rFVIIa can circumvent the actions of inhibitory antibodies present in acquired haemophilia patients. This paper provides an overview of experiences with rFVIIa for the treatment of acquired haemophilia from the NovoSeven compassionate and emergency use programmes (1989-1999), the Hemophilia and Thrombosis Research Society Registry, and independent published reports from January 1999 to September 2005. rFVIIa has been reported to provide safe and effective haemostasis as a first line therapy in patients of all ages for a variety of surgical and non-surgical bleeding situations.

International workshop on immune tolerance induction: consensus recommendations

Although immune tolerance induction (ITI) has been used for 30 years to eliminate inhibitors and restore normal factor pharmacokinetics in patients with hemophilia, there is a paucity of scientific evidence to guide therapeutic decision-making. In an effort to provide direction for physicians and hemophilia treatment center staff members, an international panel of hemophilia opinion leaders met to develop consensus recommendations for ITI in patients with severe and mild hemophilia A and hemophilia B. These recommendations draw on the available published literature and the collective clinical experience of the group and are rated based on the level of supporting evidence.

Adaptability of protein A-immunoadsorption allows temporary reduction of anti-VIII antibodies and realisation of high-risk haemorrhagic surgery

We report the successful treatment by protein A-immunoadsorption (IA) of an hemophilic man with anti-F VIII antibodies (Abs) who needed high-risk bleeding surgery. This patient had developed high levels of anti-F VIII Abs preventing substitution by clotting factor and preventing high-risk bleeding surgery. Because of rebound in Abs levels or complications, IA procedures were modified several times leading to appropriate decrease of anti-F VIII inhibitor Abs allowing bilateral knees surgery. IA procedure is enough adaptable to be modified to prevent complications. Collaboration between clinical, biological, apheresis and surgical teams implied has permitted surgery and prevented life-threatening bleeding complications.

Treatment of acquired hemophilia A

Acquired hemophilia A (AH) is an autoimmune disease that leads to potentially severe bleeding. Management relies on rapid and accurate diagnosis, control of bleeding episodes and eradication of the inhibitor by immunosuppression. There is extensive literature about the disease but only few controlled data are available. This paper reviews the current literature on treatment strategies for hemostatic therapy and inhibitor eradication. Potential future developments are discussed.

Immunoadsorption with single-use columns for the management of bleeding in acquired hemophilia A: A series of nine cases

BACKGROUND

Acquired hemophilia A in a setting of bleeding or required surgery frequently places patients into a state of critical illness with high mortality. In this context immunoadsorption (IA) can be used to eliminate coagulation inhibitors quickly to employ recombinant coagulation factors more effectively. However, since acquired hemophilia is a rare condition the therapy is little standardized.

METHODS

We report on a retrospective analysis of nine cases of acquired hemophilia A treated with IA using disposable adsorber columns. Data collection was performed by retrospectively reviewing the patients' files regarding clinical course, mode of therapy, inhibitor titers, and coagulation status.

RESULTS

Inhibitor titers were effectively reduced in all but one patient following the treatment with IA. In two out of seven patients surviving the acute bleeding an inhibitor relapse occurred. The overall remission rate was determined as 77.8% within a median follow-up of 613 days. In two of our nine patients fatal outcome resulted due to major bleeding complications. IA treatment showed good tolerability and no fatal complications were caused.

CONCLUSION

The presented cases support our assumption that patients with acquired hemophilia A benefit from IA with disposable columns in a setting of acute bleeding. This modality of IA is able to eliminate inhibitors reliably and quickly. IA in general is substantially speeding up the progress of therapy preventing bleeding complications constantly threatening the patient and reducing the dosages of coagulation factor therapy. We encourage IA with disposable columns in all bleeding patients with acquired hemophilia to aggressively lower the inhibitors.

Application of current knowledge to the management of bleeding events during immune tolerance induction

The development of inhibitors to factor VIII is the most serious adverse event associated with the treatment of haemophilia A, predisposing patients to uncontrollable haemorrhage, disability and premature death. Eradication of inhibitors via immune tolerance induction (ITI) is effective in the majority of patients, but may require months to years to achieve success. In the interim, the treatment and prevention of acute bleeding episodes are primary foci of care. Regrettably, there is a paucity of information regarding management of bleeding episodes in inhibitor patients undergoing tolerization. Until specific data from ongoing clinical trials are available to provide more guidance in this patient group, it is reasonable and useful to rely on the broader base of medical literature pertaining to patients not being tolerized to deduce strategies for controlling acute and perioperative bleeding episodes in inhibitor patients during ITI.

The diagnosis and management of factor VIII and IX inhibitors: a guideline from the United Kingdom Haemophilia Centre Doctors Organisation

The revised UKHCDO factor (F) VIII/IX Inhibitor Guidelines (2000) are presented. A schema is proposed for inhibitor surveillance, which varies according to the severity of the haemophilia and the treatment type and regimen used. The methodological and pharmacokinetic approach to inhibitor surveillance in congenital haemophilia has been updated. Factor VIII/IX genotyping of patients is recommended to identify those at increased risk. All patients who develop an inhibitor should be considered for immune tolerance induction (ITI). The decision to attempt ITI for FIX inhibitors must be carefully weighed against the relatively high risk of reactions and the nephrotic syndrome and the relatively low response rate observed in this group. The start of ITI should be deferred until the inhibitor has declined below 10 Bethesda Units/ml, where possible. ITI should continue, even in resistant patients, where it is well tolerated and so long as there is a convincing downward trend in the inhibitor titre. The choice of treatment for bleeding in inhibitor patients is dictated by the severity of the bleed, the current inhibitor titre, the previous anamnestic response to FVIII/IX, the previous clinical response and the side-effect profile of the agents available. We have reviewed novel dose-regimens and modes of administration of FEIBA (factor VIII inhibitor bypassing activity) and recombinant activated FVII (rVIIa) and the extent to which these agents may be used for prophylaxis and surgery. Bleeding in acquired haemophilia is usually treated with FEIBA or rVIIa. Immunosuppressive therapy should be initiated at the time of diagnosis with Prednisolone 1 mg/kg/d +/- cyclophosphamide. In the absence of a response to these agents within 6 weeks, second-line therapy with Rituximab, Ciclosporin A, or other multiple-modality regimens may be considered.

Health economics of treating haemophilia A with inhibitors

Haemophilia is a rare, inherited blood disorder in which blood clotting is impaired such that patients suffer from excessive internal and external bleeding. At present there is no cure for haemophilia A and patients require expensive, life-long treatment involving clotting factor replacement therapy. Treatment costs are perceived to be higher for patients who have developed inhibitory antibodies to factor VIII, the standard therapy for haemophilia A. However, initial cost analyses suggest that clotting factor therapy with alternative haemostatic agents, such as recombinant activated factor VII or activated prothrombin complex concentrate, is no more expensive for the majority of haemophilia A patients with inhibitors than for those without inhibitors. With the availability of effective alternative haemostatic agents, orthopaedic surgery for haemophilia A patients with inhibitors is now a clinical option, and initial cost analyses suggest this may be a cost-effective treatment strategy for patients with inhibitors whose quality of life (QoL) is severely impaired by joint arthropathy. In an era of finite healthcare resourcing it is important to determine whether new treatments justify higher unit costs compared with standard therapies and whether such higher costs are justified from an individual perspective in terms of improved QoL, and from a societal perspective in terms of improved productivity and reduced overall healthcare costs. This paper examines current data on the health economics of treating haemophilia A patients with inhibitors, focusing on the overall costs of clotting factor replacement therapy and the cost consequences of joint replacement.

Hemophilia management: optimizing treatment based on patient needs

PURPOSE OF REVIEW

Progress in hemophilia management over the past year has focused on improving understanding of the most common complications of genetic bleeding disorders and building upon available therapeutic strategies.

RECENT FINDINGS

Research continued to link factor VIII structure with immune recognition and inhibitor formation. Clinical regimens of immune tolerance induction confirmed and expanded basic understanding. Barriers to optimal prevention using prophylaxis were explored allowing future refinements to address unmet needs. Outcome tools to assess joint health and overall quality of life were developed and validated. The inclusion of standardized instruments in assessment of outcome will allow meaningful comparison of available therapies. Use and complications of central venous access devices (CVAD), needed to deliver aggressive infusion regimens, were exhaustively reviewed. Finally, continued progress was achieved in development of improved vectors for future gene therapy of the hemophilias.

SUMMARY

A general theme of recent progress in hemophilia management is harmonization in definitions and assessments of complications and outcomes, facilitating more rigorous and ultimately more useful interpretation of laboratory and clinical research.

Inhibitors in congenital coagulation disorders

The development of inhibitory 'allo' antibodies to a deficient coagulation factor is arguably now the most severe and important complication of clotting factor concentrate exposure in haemophilia and other congenital coagulation disorders. Furthermore, development of an inhibitor to the factor VIII or factor IX transgene product remains a significant concern in gene therapy protocols for haemophilia. Although the development of an inhibitor does not usually change the rate, initial severity or pattern of bleeding, it does compromise the ability to manage haemorrhage in affected individuals, resulting in a greater rate of complications, cost and disability. The purpose of this review is to summarize current understanding of the epidemiology, immunobiology, laboratory evaluation and management of inhibitors arising in patients with congenital coagulation disorders. An attempt has been made to focus on recent advances in the immunology of inhibitors, and to speculate on their potential clinical application.

Immunoadsorption of factor VIII inhibitors

PURPOSE OF REVIEW

Extracorporeal immunoadsorption is being increasingly applied in a variety of disorders. This approach is particularly suited to removal of antibodies or inhibitors to coagulation factor VIII and may be particularly useful before the administration of large amounts of expensive replacement or bypass therapy for patients with hemophilia who are bleeding, or patients undergoing immune tolerance therapy.

RECENT FINDINGS

In patients with inhibitors to factor VIII, several types of immunoadsorption therapy have been used, although reports are mainly anecdotal, consisting of relatively small numbers of persons. Nonetheless, the findings suggest that immunoadsorption may be clinically effective and cost-effective and should be considered early in the treatment of appropriate patients. New immunoadsorption technologies are being described for a variety of disorders, including hemophilia, and a new synthetic matrix of polystyrene beads functionalized with sulfonate and tyrosyl methylester groups for immunoadsorption removal of factor VIII inhibitors is intriguing.

SUMMARY

Although immunoadsorption was shown to be clinically effective in patients with inhibitors to factor VIII more than two decades ago, recent papers have emphasized the desirability of early implementation of the modality in the treatment plan. Immunoadsorption is relatively easy to perform with few adverse effects, but specialized equipment is required, and it should be performed in an experienced setting. Although potentially less costly than other (bypass) therapies, immunoadsorption is itself not inexpensive, and its comparative effectiveness with plasmapheresis and other management options for the dangerously bleeding patient with antibodies to factor VIII should be determined by multicenter randomized controlled trials. Interesting recent novel technical developments in the field may facilitate increased use of the procedure.