A survey of factor prophylaxis in boys with haemophilia followed in North American haemophilia treatment centres

Summary.  A survey was conducted in 2002 to determine the pattern of factor prophylaxis use in boys ≤18 years of age with haemophilia followed in North American treatment centres. Responses were obtained from 4553 cases (74% haemophilia A, 26% haemophilia B). The frequency of prophylaxis, defined as factor infusion greater than or equal to once per week for ≥45 weeks per year, was significantly higher for haemophilia A vs. haemophilia B cases (51% vs. 32%, P < 0.0001), and for boys with severe haemophilia A living in Canada vs. the USA (77% vs. 47%, P < 0.0001). Use of full-dose prophylaxis, defined as the infusion of 25–40 IU kg⁻¹ of factor VIII on alternate days (minimum three times per week) or 25–40 IU kg⁻¹ of factor IX twice weekly, was similar for boys ≤5 years of age in both Canada and the USA (30% and 33% haemophilia A and 35% and 13% haemophilia B). Reasons for initiating prophylaxis included a history of joint bleeding (88%) and age ≤2 years (23%). For prophylaxis triggered by joint bleeding, 38% of haemophilia treatment centres indicated that they would initiate prophylaxis after the first joint bleed and 66% after a history of target joint bleeding, defined most frequently as 2–4 bleeds over a 3–6 consecutive month period. A central venous line was used to ensure easy venous access for full-dose prophylaxis therapy in 80% of boys ≤5 years of age. These data offer a basis for projecting long-term factor concentrate needs for persons with haemophilia living in North America.     

The use of prophylaxis in 2663 children and adults with haemophilia: results of the 2006 Canadian national haemophilia prophylaxis survey

Summary. Prophylaxis is standard of care for boys with severe haemophilia A. Indications for prophylaxis in adulthood, non‐severe haemophilia A, haemophilia B and haemophilia with inhibitors are less well defined. This survey, conducted in 2006, aimed to describe prophylaxis use in patients of all ages and severities with haemophilia A or haemophilia B in Canada. Data on 2663 individuals (2161 haemophilia A; 502 haemophilia B), including 78 inhibitor‐positive patients, were returned by 22/25 Canadian haemophilia treatment centres. This represented 98% of the Canadian haemophilia population. Frequency of prophylaxis use, defined as infusion of factor VIII/IX concentrate at least once weekly for ≥45 weeks of the year, was highest in individuals with severe haemophilia A (69%). It was lower in individuals with severe haemophilia B (32%), moderate haemophilia A (18%) or B (5%) and mild haemophilia A (1%) or B (1%). Among individuals with severe haemophilia A, the frequency of prophylaxis use was 84% in children (≤18 years) and 55% in adults (>18 years). Thirteen per cent of inhibitor‐positive individuals were receiving prophylaxis with bypassing agents. Comparison with data obtained from a 2002 Canadian survey showed a greater use of prophylaxis in children ≤5 years of age with severe haemophilia A (73% vs. 49%). Prophylaxis is no longer confined to children with severe haemophilia A, but is used in a significant proportion of adults with severe haemophilia A and individuals with severe haemophilia B or moderate haemophilia A. Prophylaxis is being started earlier in boys with severe haemophilia A.     

Optimizing factor prophylaxis for the haemophilia population: where do we stand?

Summary. The hallmark of severe haemophilia, defined as a circulating level of factor (F) VIII (haemophilia A cases) or FIX (haemophilia B cases) of < 1%, is recurrent bleeding into muscles and joints (haemarthroses) from an early age of life. The inevitable result of such bleeding is progressive joint damage, leading to disabling arthritis that is typically evident within the first 2 decades of life in people with haemophilia who have limited or no access to regular factor replacement therapy, or those in whom factor replacement therapy is ineffective because of the presence of high‐titre inhibitors. For children with severe haemophilia and no evidence of inhibitors, the unwanted musculoskeletal complications of severe haemophilia can be effectively prevented by the early initiation of a programme of long‐term factor prophylaxis. In order to achieve the best outcome (a perfect musculoskeletal status for age) the programme of prophylaxis should be started before the onset of joint damage (primary prophylaxis). The gold standard primary prophylaxis regimen (the Malmö protocol) was pioneered and tested in Sweden and involves the infusion of 20–40 IU of FVIII per kg body weight on alternate days (minimum three times per week) for haemophilia A cases, and 20–40 IU kg^?1 of FIX twice weekly for haemophilia B cases. This protocol is, however, demanding on peripheral veins and very expensive. Modifications of the parent protocol such as starting primary prophylaxis with once‐weekly infusions via peripheral veins with rapid escalation to full‐dose prophylaxis or dose escalation based on frequency of bleeding are increasingly implemented in haemophilia treatment centres in countries that can afford the high cost of such programmes. These modified programmes can be achieved in the majority of young children with severe haemophilia without the need for central venous access devices (e.g. Port‐a‐Caths) and with avoidance of device‐associated complications such as infection and thrombosis. In at least one centre, experience with arteriovenous fistulae as a strategy to ensure reliable venous access is being accumulated. The issues of compliance (adherence) to recommended prophylaxis protocols and when, if ever, to stop a programme of primary prophylaxis once started are real and require ongoing prospective studies. Such studies should incorporate outcome measures such as health‐related quality‐of‐life and economic analyses.     

Factor VIII prophylaxis for adult patients with severe haemophilia A: results of a US survey of attitudes and practices

Summary.  The emergence of a population of relatively healthy adults with severe haemophilia A presents a unique challenge for haemophilia care in the 21st century. Understanding how best to continue, restart, initiate or modify prophylaxis in younger and older adult patients is essential to optimizing their care. To elucidate practice and outcome data, a survey was sent to 23 US hemophilia treatment centers (HTCs); 10 centers responded, providing data concerning up to 145 adults (mean age of 34 years). Forty-eight patients (33%) were on regular prophylaxis when first seen at the HTC; the prophylactic regimen was modified for 22/48 (46%), often because of breakthrough bleeding. Five of 21 patients (24%) for whom data were available discontinued prophylaxis. Three of those five patients (60%) experienced increased bleeding episodes and the other two (40%) subsequently resumed regular prophylactic infusions because of the increased bleeding. Of the 77 patients not initially receiving prophylaxis for whom data were available, prophylaxis was started or resumed in all. The prophylactic regimen was modified in 57/77 patients (74%) at some point during treatment, often because of breakthrough bleeding. Of the 55 patients whose prophylactic regimens were modified for whom data were available, 22 (40%) discontinued prophylaxis. Thirteen of 20 patients (65%) for whom data were available experienced an increase in bleeding episodes and 7/18 patients (39%) who had discontinued prophylaxis and for whom data were available subsequently resumed regular prophylactic infusions because of bleeding. These findings suggest that prophylaxis prevents bleeding in adults with severe haemophilia A and that discontinuation of the prophylactic regimen is associated with increased bleeding events.     

Prevention and treatment of musculoskeletal disease in the haemophilia population: role of prophylaxis and synovectomy

Summary.  Prophylaxis is defined as primary (started before the onset of joint damage) or secondary (started after the onset of joint damage). The aim of primary prophylaxis is to prevent recurrent bleeding into joints and the development of chronic arthropathy in later life. When started early, and at most after two joint bleeds, the result is predictably excellent if there is compliance with the primary prophylaxis regimen. In order to decrease the need for central venous access devices to assure reliable venous access, a number of centres start primary prophylaxis with once weekly infusions with dose-escalation based on frequency of joint bleeding. A major unanswered question is whether primary prophylaxis can be safely discontinued in adolescents/young adults and if so, when. A promising predictor for the milder bleeding phenotype in persons with severe haemophilia is a later onset of joint bleeding. Once joint damage has occurred as a result of recurrent bleeding, secondary prophylaxis can only retard, but not prevent, ongoing joint damage. Other strategies to decrease recurrent bleeding from target joints include surgical synovectomy (ideally performed using an arthroscopic technique), radionuclide synovectomy and chemical synovectomy. These interventions have very good outcomes when performed by an experienced team. Given the very high cost of factor concentrates required for programmes of prophylaxis prospective studies that document benefits to the child and family, e.g. quality of life are to be encouraged.     

Revisiting the cost-effectiveness of primary prophylaxis with clotting factor for the treatment of severe haemophilia A

Summary.  Severe haemophilia A is a lifelong condition that requires treatment with exogenous clotting factor. While primary prophylaxis is the clinically preferred method of delivering treatment, its provision is costly. A 2002 evaluation of primary prophylaxis suggested an incremental cost-effectiveness of approximately £50 000 per additional quality-adjusted life-year (QALY). However, since this time, preferable evaluative methods have been developed and means of assessing the value of future research also now exist. Thus, the primary aims of this study were to update a previously published cost-effectiveness analysis of primary prophylaxis vs. treating on-demand in terms of methods and to estimate the value of undertaking further primary research. The base case incremental cost-effectiveness ratio was shown to be approximately £37 000, £10 000 lower than the value published in 2002. The main reason for this difference was the use of different structural assumptions and methods to fit the various model parameters. At a willingness to pay per additional QALY threshold of £30 000, the probability prophylaxis is cost-effective was 13%. However, this increased to over 90% when alternative structural assumptions were employed, such as the rate at which future QALYs are discounted. The value of further research to increase the precision of this newly calculated cost-effectiveness estimate was high at a threshold willingness to pay values of £30 000–£40 000 per QALY, particularly for the utilities associated with the health states. Thus, there is considerable value in conducting further primary research related to economic aspects of primary prophylaxis.     

Adverse events in the prophylaxis of haemophilia

Summary.  Whilst prophylaxis undoubtedly offers many advantages, the potential for adverse effects must also be borne in mind. Modern plasma-derived products have an extremely good safety record with regard to transmission of pathogens, although continuous vigilance is required as new pathogens continue to emerge, eg new variant Creutzfeldt-Jakob disease. There is no evidence that prophylactic treatment is associated with an increased incidence of inhibitors, and it is now recognized that genetic factors are the most significant in conferring susceptibility. Although subtle immunological abnormalities have also been observed in patients with haemophilia, there is no evidence that these are of any clinical significance. There has been a growing trend to use indwelling venous catheters for prophylaxis. The risk of infection has been appreciated for some time, although it has only recently been possible to quantify this with more precision. The risk of catheter-associated thrombosis is now recognized to be higher than hitherto appreciated. Whilst sporting activities are to be encouraged, there is a potential for significant trauma in children with prophylaxis, as plasma coagulation factor levels remain far below normal with the usual regimens.     

Assessing the benefits of FEIBA prophylaxis in haemophilia patients with inhibitors

Summary. Prophylaxis with concentrates of factor VIII has become the standard of care for patients with severe haemophilia A because of its ability to prevent joint and other bleeding events. Recent evidence suggests that the prophylactic use of bypassing therapy – activated prothrombin complex concentrate (aPCC) and recombinant activated factor VII (rFVIIa) – provides similar benefits to haemophilia patients with inhibitors. To assess the efficacy and safety of prophylaxis with the aPCC FEIBA, a meta‐analysis was conducted of six studies and a total of 34 inhibitor patients. The mean prophylactic dose was 78.5 U kg^?1, typically infused three to four times weekly. A total of 31 of 33 patients (94%) for whom bleeding data were available prior to prophylaxis experienced a decrease in the rate of haemorrhage, albeit minor in some patients, and, regardless of the type of haemorrhage measured, had on average a 63.9% reduction in bleeding episodes during FEIBA prophylaxis. In the three studies that specifically assessed all joint bleeding, the 18 patients evaluated experienced an average reduction in annual joint bleeding of 74% while on prophylactic regimens. Among the four patients in this group who received concurrent immune tolerance induction and the 14 patients treated with prophylaxis only, annual joint bleeding decreased by an average of 79% and 78%, respectively. Anamnesis following FEIBA exposure was observed in some patients but had no impact on prophylactic efficacy. No thrombotic or other complications were reported. These results suggest that the prophylactic administration of FEIBA can be an effective and safe method for reducing bleeding events in patients with haemophilia A and inhibitors.     

Survey of current prophylaxis practices and bleeding characteristics of children with severe haemophilia A in US haemophilia treatment centres

Summary. Every other day (qod) factor VIII prophylaxis prevents joint bleeds in children with severe haemophilia A. Although three times weekly or qod prophylaxis is recommended by the National Hemophilia Foundation (NHF), how widely these practices have been adopted is not known. We sought to define current prophylaxis practices at US haemophilia treatment centres (HTCs). An email survey was distributed to US HTCs, utilizing web‐based membership rosters of the Centers for Disease Control (CDC) and the Hemostasis Thrombosis Research Society (HTRS). Of 62 HTCs responding, prophylaxis is initiated on a three times weekly schedule in 29 (46.8%), twice weekly in 13 HTCs (21.0%) and once weekly in 20 HTCs (32.2%). Central venous catheters are used to infuse factor prophylactically at 55 HTCs (88.7%), including in 100% of children initiating prophylaxis at 19 HTCs (30.6%) and in 50% of those at 41 HTCs (66.1%), but avoided altogether at seven HTCs (11.3%). Prophylaxis is initiated after one or more bleeds in 56 HTCs (90.3%), but after the first bleed in only 28 HTCs (25.2%). Among 226 newborns with severe haemophilia A in 62 HTCs, 1.82 births/HTC/year, the median age at first bleed, excluding circumcision, is 7 months. Of the 113 (53.5%) newborns who underwent circumcision, 62 (54.9%) bled. Despite a recommended standard of three times weekly prophylaxis, over half of surveyed HTCs do not follow these guidelines, and nearly one‐third begin prophylaxis on a once weekly schedule to delay or avoid the need for central venous access.     

A comparison of traditional vs. Canadian tailored prophylaxis dosing of prophylactic factor infusions in children with haemophilia A and B in a single hemophilia treatment center

Prophylactic infusion of clotting factor concentrates is a developing standard of care for individuals with haemophilia. The ideal schedule and techniques of prophylactic infusions remain incompletely defined. Our aim was to determine the optimal techniques and schedules for factor prophylaxis in paediatric patients. A retrospective electronic medical record review of all children treated with prophylactic factor infusions in a single Haemophilia Treatment Center was conducted. Comparison of traditional vs. Canadian dosing regimens and primary vs. secondary prophylaxis was made. Failure of prophylaxis was defined as the first serious bleed. A total of 58 children were identified for review. Five cases were excluded (four due to high titre inhibitors and one due to repeated non-compliance), thus there were 53 total cases: 46 with severe haemophilia, 2 with moderate haemophilia, 5 with mild haemophilia, 44 with haemophilia A and 9 with haemophilia B; 32 Traditional dosing and 21 Canadian dosing regimens. Patients on primary prophylaxis had a decreased failure rate (25%) compared to children treated with secondary prophylaxis (67%) regardless of technique of prophylaxis. When compared to a 'Traditional' factor prophylaxis schedule, the 'Canadian' tailored prophylaxis protocol was comparable with the exception of a decreased use of implanted venous devices in the 'Canadian' group. Ongoing bleeding (primarily joint bleeds) occurs with all prophylactic regimens. The lowest incidence of treatment failure was noted in children who began primary prophylaxis at a young age and before initial joint bleeds. Primary prophylaxis is superior to secondary prophylaxis regardless of dosing regimen. Traditional and Canadian dosing regimens were equivalent in outcome when measured over several years of follow-up.     

Targeting higher factor VIII levels for prophylaxis in haemophilia A: a narrative review

Introduction

The standard of care in severe haemophilia A is prophylaxis, which has historically aimed for a factor VIII (FVIII) trough level of ≥1%. However, despite prophylactic treatment, people with haemophilia remain at risk of bleeds that have physical and quality of life implications, and that impact everyday life.

Aim

The aim of this review was to evaluate evidence supporting the relationship between targeting higher FVIII activity levels with prophylaxis and improved outcomes in people with haemophilia A.

Methods

We conducted a narrative review that defined the unmet needs and treatment goals in people with haemophilia A, evaluated evidence to support targeting higher FVIII activity levels, and highlighted therapies that may support higher and sustained FVIII activity levels and improved outcomes for people with haemophilia A.

Results

Despite recent advances in treatment, unmet needs remain, and people with haemophilia continue to experience joint and functional impairment, acute and chronic pain, and poor mental health. All these negatively impact their health-related quality of life. Evidence suggests that FVIII activity levels of up to 50% may be needed to achieve a near-zero joint bleed rate. However, achieving high FVIII activity levels with current standard and extended half-life (EHL) FVIII replacement therapies is associated with a high treatment burden. Innovative treatment options may provide high sustained FVIII activity levels and improved patient outcomes.

Conclusion

Evidence suggests that FVIII activity levels in people with haemophilia A should be sustained at higher levels to improve joint and patient outcomes and enable progression towards health equity.     

Barriers to compliance with prophylaxis therapy in haemophilia

Prophylaxis, or the practice of routine replacement infusions of clotting factor concentrate in persons with severe haemophilia, is a demanding medical regimen. Prophylactic infusions require direct venepuncture or sterile entry into a central venous access device on a regular basis. A telephone survey was conducted to elicit information regarding the barriers to compliance with prophylaxis. The Mountain States Regional Haemophilia and Thrombosis Center has recommended prophylaxis to 52 male patients with haemophilia A or B. The haemophilia nurse attempted to contact all of these patients or their parents, and contact was made with 38 (73.1%) of them. Respondents were asked about the following issues: their decision to initiate prophylaxis; their self-rated compliance; the challenges, barriers, and facilitators of prophylaxis; and their perceived value of the therapy. Four patients (10.5%) elected not to begin prophylaxis. Of the 34 persons who began prophylaxis, 20 respondents (58.8%) rated their compliance as excellent. Nearly one-third of the families with excellent compliance (giving 75-100% of prescribed infusions) stated that the time-consuming nature of prophylaxis was the most significant challenge of the regimen. In addition, 58.3% of the families that gave less than the prescribed number of infusions reported that the time commitment was the primary reason for missing infusions. Knowledge of the benefits of prophylaxis was the primary facilitator of compliance for 44.1% of families. Ninety-seven percent of respondents rated prophylaxis as very valuable. These data show that despite the known benefits of prophylaxis, it is a demanding medical regimen, and compliance is imperfect. In addition, this study underscores the importance of providing continuing support and education for patients and families who are implementing prophylaxis.     

Aspects of haemophilia prophylaxis in Sweden

Summary.  Prophylactic treatment of haemophilia has been gaining acceptance as the optimal therapeutic option in an increasing number of haemophilia centres in the developed world in recent years. This paper focus on three aspects of prophylactic therapy: when to start treatment, venous access and the dose/dose interval. Evidence is in favour of prophylactic treatment to be started at an early age using either a peripheral vein with 1–2 injections per week and a successive increase in the frequency depending on the child and the veins, or, using a Port-A-Cath which allows a better prophylactic coverage by infusions preferably every second day in haemophilia A and every third day in haemophilia B.