The Jamaican Haemophilia Registry: Describing the burden of disease

INTRODUCTION

Jamaica has an estimated 200 persons with haemophilia (PWH), who face significant constraints in access to specialized haemophilia care, including access to clotting factor concentrates.

AIM

The aim of this paper is to establish the current burden of disease in PWH in Jamaica.

METHODS

PWH were enrolled through the University Hospital of the West Indies, Jamaica. The impact of haemophilia was assessed using a comprehensive battery of heath outcome measures that included the following: laboratory, clinical information and validated outcome measures of joint structure and function, activity, and health-related quality of life (HRQoL) to provide a health profile of the Jamaican haemophilia population.

RESULTS

In all, 45 PWH were registered (mean age: 29, range: 0.17-69 years), including 13 children (<18 years of age) and 32 adults. In this sample, 41 had haemophilia A (30 severe) and 4 had haemophilia B (3 severe); 10 patients with haemophilia A were inhibitor positive. The results indicate that adults with haemophilia in Jamaica have significant joint damage: mean Haemophilia Joint Health Score (HJHS) = 42.1 (SD = 17.3); moderate activity levels - mean Haemophilia Activities List (HAL) score = 64.8 (SD = 17.8); and low HRQoL scores - mean Haemo-QoL-A score = 62.3 (SD = 19.4). Results for children are also reported but should be interpreted with caution due to the small sample size.

CONCLUSIONS

There is a very high burden of disease in PWH in Jamaica. The health profiles reported in this paper are an essential first step in advocating for a multidisciplinary Comprehensive Care Program for assessment and care of PWH in Jamaica.

von Willebrand Disease in a Pediatric-based Population - Comparison of Type 1 Diagnostic Criteria and Use of the PFA-100® and a von Willebrand Factor/Collagen-binding Assay

Definitive diagnosis of type 1 von Willebrand Disease (VWD) remains a problem. Provisional consensus guidelines for the diagnosis of definite and possible type 1 VWD were prepared by the Scientific Subcommittee on von Willebrand factor (VWF) of the Scientific and Standardization Committee (SSC) of the International Society on Thrombosis and Haemostasis (ISTH) during the 1996 annual meeting for the specific purpose of further evaluation in retrospective and prospective studies by a Working Party on Diagnostic Criteria (1996 Annual Report of the SSC/ISTH Subcommittee on VWF). In the first phase of this study, we compared 2 definitions of type 1 VWD, each with 3 criteria: significant bleeding history, laboratory investigations, and family history. Using the ISTH consensus guidelines for type 1 VWD definition, significantly fewer patients were diagnosed with definite type 1 disease as compared to our “in house” Hospital for Sick Children (HSC) criteria (4 vs. 31). While we recognize that the provisional ISTH consensus guidelines were not intended for clinical use, we believe that the results of our studies are of interest and will assist in any future refinements to the ISTH guidelines.

In the second phase of this study, we investigated the utility of 2 new tests, a laboratory screening test and a functional test, for VWD in our well characterized, pediatric-based population. The Platelet Function Analyzer (PFA-100®) provides an in vitro measure of primary hemostasis under conditions of high shear, using disposable cartridges containing collagen and either epinephrine or ADP. All tested subjects with types 2 or 3 VWD had prolonged PFA-100 closure times (CTs) with both cartridge types (n = 17) and prolonged bleeding times (n = 14). In subjects with definite type 1 VWD, 20/24 (83%) had prolonged CTs with the collagen/ADP cartridge (19/24 (79%) with collagen/epinephrine), compared with 7/26 (27%) with prolonged bleeding times. In subjects with definite types 1, 2, or 3 VWD, collagen/ADP CTs were abnormal in 37/41 subjects, giving an overall sensitivity of 90%. With this high sensitivity, the PFA-100 is a better screening test for VWD than the bleeding time.

We also tested a VWF collagen-binding assay (VWF:CBA) as a functional test for VWF, in comparison with the more routinely-used ristocetin cofactor assay (VWF:RCo). The VWF:CBA is based on an ELISA technique, which has the potential to be more reproducible than the VWF:RCo. We found that the VWF:CBA detected 43/49 (88%) subjects with definite types 1, 2, or 3 VWD, performing as well as the VWF:RCo, that detected 42/48 (88%). We also showed that, used in conjunction with VWF antigen levels, the VWF:CBA may be useful in classification of VWD subtypes.

Improved joint health in subjects with severe haemophilia A treated prophylactically with recombinant factor VIII Fc fusion protein

INTRODUCTION

Joint arthropathy is the long-term consequence of joint bleeding in people with severe haemophilia.

AIM

This study assessed change in joint health over time in subjects receiving recombinant factor VIII Fc fusion protein (rFVIIIFc) prophylaxis.

METHODS

ALONG is the phase 3 pivotal study in which the benefit of rFVIIIFc as a prophylactic treatment for bleeding control was shown in previously treated severe haemophilia patients ≥12 years of age (arm 1: 25-65 IU/kg every 3-5 days, arm 2: 65 IU/kg weekly and arm 3: episodic). After completing ALONG, subjects had the option to enrol into the extension study (ASPIRE). This interim, post hoc analysis assessed changes in joint health over ~2.8 years in these patients.

RESULTS

Forty-seven subjects had modified Haemophilia Joint Health Score (mHJHS) data at A-LONG baseline, ASPIRE baseline and ASPIRE Year 1 and Year 2. Compared with A-LONG baseline (23.4), mean improvement at ASPIRE Year 2 was -4.1 (95% confidence interval [CI], -6.5, -1.8; P = .001). Regardless of prestudy treatment regimen, subjects showed continuous improvement in mHJHS from A-LONG baseline through ASPIRE Year 2 (prestudy prophylaxis: -2.4, P = .09; prestudy episodic treatment: -7.2, P = .003). Benefits were seen in subjects with target joints (-5.6, P = .005) as well as those with severe arthropathy (-8.8, P = .02). The mHJHS components with the greatest improvement at ASPIRE Year 2 were swelling (-1.4, P = .008), range of motion (-1.1, P = .03) and strength (-0.8, P = .04).

CONCLUSIONS

Prophylaxis with rFVIIIFc may improve joint health over time regardless of prestudy prophylaxis or episodic treatment regimens.

Describing the quality of life of boys with haemophilia in China: Results of a multicentre study using the CHO-KLAT

INTRODUCTION

The treatment of haemophilia varies across countries and across regions within some countries. Similar variation has been observed in health-related quality of life (HR-QoL). Relatively little is known about the HR-QoL of boys with haemophilia in China.

AIM

The aim of this study was to describe the HR-QoL of boys with haemophilia in China using the Canadian Haemophilia Outcomes-Kids Life Assessment Tool (CHO-KLAT).

METHODS

Boys (4-18 years of age) with haemophilia and their parents were enroled in a cross-sectional study. All parents/guardians of study subjects were requested to complete a CHO-KLAT questionnaire during a clinic visit, and report on several other clinical and socioeconomic factors in the past year. Boys who were > 7 years also completed the CHO-KLAT.

RESULTS

A total of 269 parents of boys with haemophilia, from 13 hospitals in 12 provinces, were enroled during 2014. The boys ranged from 4.0 to 17.9 years of age; 91% had haemophilia A, most had moderate (52%) or severe (36%) disease, and most were receiving sub-optimal on-demand therapy or low-dose prophylactic therapy. Child self-report CHO-KLAT scores were available for 171 boys ≥7 years of age and ranged from 24.2 to 85.3 with a mean of 57.6 (n = 171). Parent proxy-reported CHO-KLAT scores ranged from 25.0 to 88.7 with a mean of 55.1 (n = 269).

CONCLUSION

HR-QoL scores in boys with haemophilia in China were substantially lower than reported from Canadian and European boys with haemophilia. Longer term prospective studies are required to examine the factors impacting the HR-QoL for boys with haemophilia in China.

Imaging of haemophilic arthropathy in growing joints: pitfalls in ultrasound and MRI

The purpose of this review was to summarize the current knowledge on the utilization of magnetic resonance imaging (MRI) and ultrasound (US) for assessing arthropathy in children and adolescents with haemophilia and to recognize the limitations of each imaging modality and pitfalls in the diagnosis of soft tissue and osteochondral abnormalities. Awareness of MRI and US limitations and pitfalls in the assessment of joints in persons with haemophilia is essential for accurate diagnosis and optimal management of haemophilic arthropathy.

A systematic review of ultrasound imaging as a tool for evaluating haemophilic arthropathy in children and adults

The purpose of this study was to semi-quantitatively assess the evidence on the value of ultrasound (US) for assessment of haemophilic arthropathy (HA) in children and adults based on the following questions: (1) Does early diagnosis of pathological findings, using available US techniques, impact the functional status of the joint? (2) Do current available US techniques have the ability to accurately detect pathological changes in target joints in haemophilic patients? (3) Does treatment (prophylaxis) improve US evidence of haemophilic arthropathy in children and adults? (4) Is there any association between various US scoring systems and other clinical/radiological constructs? Of the 6880 citations identified searching databases such as MEDLINE, Embase, CENTRAL and Web of Science, 20 articles investigating either the diagnostic accuracy of US and/or US scanning protocols and scoring systems for assessment of HA met the inclusion criteria for the study. Of these, 14 articles evaluating the diagnostic accuracy of US were assessed by two independent reviewers for reporting quality using the Standards for Reporting of Diagnostic Accuracy (STARD) tool and for methodological quality using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Using STARD, 1/14 studies (7%) was scored as of high reporting quality and 8/14 (57%), of moderate quality. Assessment with QUADAS-2 reported 2/14 (14%) studies as having high methodological quality and 6/14 (43%) as having moderate quality. There is fair evidence (Grade B) to recommend US as an accurate technique for early diagnosis of HA, to demonstrate that US scores correlate with clinical/US constructs and to prove an association between US findings and functional status of the joint. However, there is insufficient evidence (Grade I) to conclude that US-detectable findings in HA are sensitive to changes in therapy.

A prospective study of health-related quality of life of boys with severe haemophilia A in China: comparing on-demand to prophylaxis treatment

INTRODUCTION

Treatment for boys with haemophilia in China is rapidly improving; however, comprehensive outcomes have not been examined prospectively.

AIM

The aim of this study was to evaluate the effect of short-term full-dose prophylaxis compared to on-demand treatment, on the Health-Related Quality of Life (HR-QoL) of boys with severe haemophilia A (HA) in China.

METHODS

Boys with severe HA (FVIII<1%) completed 3 months of on-demand treatment and 3 months of full-dose prophylaxis (25 FVIII IU per kg 3x per week). The primary outcomes were child- and parent-reported Canadian Hemophilia Outcomes - Kids Life Assessment Tool (CHO-KLAT) scores. The number and type of bleeds and Activities Scale for Kids (ASK) scores were also recorded.

RESULTS

Analyses included 23 boys between 4 and 15.9 years of age. The number of bleeds decreased by 94% on prophylaxis (P < 0.0001, Wilcoxon Signed-Rank test). The mean child-reported CHO-KLAT scores for boys ≥7 years (n = 20) was 61.4 (±10.9) during on-demand treatment and 61.9 (±11.4) following short-term prophylaxis (P = 0.72, paired t-test). The mean parent-reported CHO-KLAT score during the on-demand phase was 54.4 (±10.5) with an increase of 3.8 points (±8.1; P = 0.04, paired t-test) following prophylaxis.

CONCLUSIONS

Child-reported CHO-KLAT scores were lower in boys with severe HA in China than reported in countries with access to full-dose prophylaxis. Boys reported higher HR-QoL scores than their parents. Small improvements in ASK scores were noted following the prophylaxis phase. These changes were only significant in the parent-reported CHO-KLAT scores. Longer term prospective clinical trials are needed in China to determine the impact of prophylaxis on HR-QoL in boys with severe HA.

Validity of the Portuguese CHO-KLAT in Brazil

INTRODUCTION

It is essential to assess the health-related quality of life outcomes of boys with haemophilia in Brazil. The Canadian Haemophilia Outcomes-Kids Life Assessment Tool (CHO-KLAT) was recently adapted for this population.

AIM

To test the construct validity of the Portuguese version of the CHO-KLAT.

METHODS

We recruited 50 boys, with moderate [factor VIII (FVIII) level 1-5%] or severe (FVIII level <1%) haemophilia, to participate in a descriptive study to establish a baseline understanding of the current status of boys with haemophilia in Brazil. All boys were required to complete the Brazilian CHO-KLAT and Brazilian Pediatric Quality of Life Inventory (PedsQL) by self-report. We examined the correlation between the CHO-KLAT and PedsQL scores to establish the construct validity of the Brazilian version of the CHO-KLAT.

RESULTS

We obtained CHO-KLAT and PedsQL data from 35 boys with severe haemophilia and 15 with moderate haemophilia. They ranged in age from 7.3 to 18.0 years, with a mean of 13.0 years. They reported a mean CHO-KLAT score of 72.3 (range = 44.1-93.9). The mean PedsQL score was 79.9 (range = 45.7-96.7), with physical health (mean of 83.9) being better than psychosocial health (77.8). The Pearson's correlation between CHO-KLAT and PedsQL was 0.47 respectively (P < 0.001). The CHO-KLAT had a moderate and inverse relationship with the degree to which they were bothered by their haemophilia (ρ = -0.53), while the PedsQL had a weaker relationship (ρ = -0.27).

CONCLUSION

The results confirm the validity of the Portuguese version of the CHO-KLAT. This measure is now available for clinical trials in boys with haemophilia in Brazil.

International cross-cultural validation study of the Canadian haemophilia outcomes: kids' life assessment tool

Health-related quality of life (HRQoL) assessment is recognized as an important outcome in the evaluation of different therapeutic regimens for persons with haemophilia. The Canadian Haemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT) is a disease-specific measure of HRQoL for 4 to 18-year-old boys with haemophilia. The purpose of this study was to extend this disease-specific, child-centric, outcome measure for use in international clinical trials. We adapted the North American English CHO-KLAT version for use in five countries: France, Germany, the Netherlands, Spain and the United Kingdom (UK). The process included four stages: (i) translation; (ii) cognitive debriefing; (iii) validity assessment relative to the PedsQL (generic) and the Haemo-QoL (disease-specific) and (iv) assessment of inter and intra-rater reliability. Cognitive debriefing was performed in 57 boys (mean age 11.4 years), validation was performed in 144 boys (mean age 11.0 years) and reliability was assessed for a subgroup of 64 boys (mean age 12.0 years). Parents also participated. The mean scores reported by the boys were high: CHO-KLAT 77.0 (SD = 11.2); PedsQL 83.8 (SD = 11.9) and Haemo-QoL 79.6 (SD = 11.5). Correlations between the CHO-KLAT and PedsQL ranged from 0.63 in Germany to 0.39 in the Netherlands and Spain. Test-retest reliability (concordance) for child self-report was 0.67. Child-parent concordance was slightly lower at 0.57. The CHO-KLAT has been fully culturally adapted and validated for use in five different languages and cultures (in England, the Netherlands, France, Germany and Spain) where treatment is readily available either on demand or as prophylaxis.

A pilot randomized control trial to evaluate the feasibility of an Internet-based self-management and transitional care program for youth with haemophilia

Adolescents with haemophilia must assume responsibility for their health and management of their disease. An online self-management program was developed to support adolescents during this transition. To determine the feasibility of the program using a randomized control trial (RCT) design in terms of accrual/attrition rates, willingness to be randomized, compliance with the program/outcome measures and satisfaction. Adolescents, ages 13-18, were enrolled in a pilot RCT (NCT01477437) and randomized to either the intervention (8-week program with telephone coaching) or the control arm (no access to the website, weekly telephone call as attention-strategy). All participants completed pre/post-outcome measures. Twenty-nine teens participated (intervention n = 16, control n = 13). Participants in the intervention arm spent an average of 50 min on the website per week and completed the modules in an average of 14 weeks (SD = 4.9). Attrition was higher in the control group compared to the intervention group (54% vs. 25%). 17/18 (94%) who completed the program also completed the poststudy measures. Teens on the intervention arm showed significant improvement in disease-specific knowledge (P = 0.004), self-efficacy (P = 0.007) and transition preparedness (P = 0.046). There was a statistically significant improvement in knowledge in the intervention group when compared to the control group (P = 0.01). Overall, the teens found the website to be informative, comprehensive and easy to use and were satisfied with the program. This pilot RCT study suggests benefit to the program and indicates an RCT design to be feasible with minor adjustments to the protocol.

The genetics of Canadian type 3 von Willebrand disease: further evidence for co-dominant inheritance of mutant alleles

BACKGROUND

Type 3 von Willebrand disease (VWD) is the most severe form of the disease and is classically inherited in an autosomal recessive fashion.

OBJECTIVES

The aim of the current study was to investigate the molecular pathogenesis of a Canadian cohort of type 3 VWD patients.

PATIENTS AND METHODS

Thirty-four families comprised of 100 individuals were investigated. Phenotypic data, including bleeding scores (BS), von Willebrand factor (VWF) laboratory values and anti-VWF inhibitor status were included as well as sequence analysis.

RESULTS

We identified 31 different mutations (20 novel): 8 frameshift, 5 splice site, 9 nonsense, 1 gene conversion, 6 missense and 2 partial gene deletion mutations. The majority of mutations identified were in the propeptide (42%); index cases (IC) with these mutations exhibited more severe bleeding (BS = 22) than those with mutations elsewhere in VWF (BS = 13). Sixty-two out of 68 (91%) mutant alleles were identified. Twenty-nine IC (85%) had a VWF null genotype identified; 17 homozygous, 12 compound heterozygous. In five IC (15%), two mutant VWF alleles were not identified to explain the type 3 VWD phenotype. In four ICs only one mutant VWF allele was identified and in one IC no mutant VWF alleles were identified.

CONCLUSIONS

We have investigated the molecular pathogenesis of a Canadian cohort of type 3 VWD patients. Obligate carriers are not phenotypically silent in the Canadian population; 48% have been diagnosed with type 1 VWD. In approximately 50% of families in this study the inheritance pattern for type 3 VWD is co-dominant and not recessive.

Expanded phenotype-genotype correlations in a pediatric population with type 1 von Willebrand disease

BACKGROUND

Recent phenotype-genotype studies have provided valuable insights into the pathophysiology of type 1 von Willebrand disease (VWD); however, no study has examined an exclusively pediatric cohort.

OBJECTIVES

To describe phenotype-genotype correlations in a selected pediatric cohort with a historical diagnosis of type 1 VWD, using first-degree family members as controls.

METHODS

Comprehensive phenotypic assessment included standard assays of von Willebrand factor (VWF) level and function, bleeding score, desmopressin response, VWF propeptide (VWFpp) level, and platelet-derived VWF mRNA level.

RESULTS

Fourteen VWF mutations were identified in 17 of 23 index cases (ICs) (aged 5-17 years), including four that were previously unreported (L60P, nt1658 insT, Q1388X, and C2237F). VWFpp levels were lower in ICs than in unaffected controls (median 49 vs. 86 U dL(-1) , P < 0.0001). A VWFpp/VWF antigen ratio of > 1.6 was observed in eight of nine ICs with a suboptimal response to desmopressin, including four of four with the R1205H (Vicenza) mutation (median 7.9), and three of four IC with the R1315C mutation (median 1.9). The R1315C mutation was also associated with a reduced absolute VWFpp level (median 32 U dL(-1) ), a previously unreported finding. The amount of platelet-derived VWF mRNA was significantly reduced in individuals with nonsense mutations.

CONCLUSIONS

Increased VWF clearance and intracellular retention are important mechanisms underlying type 1 VWD in pediatric patients, concordant with the observations of larger, predominantly adult, cohort studies. Additionally, in some patients, nonsense-mediated decay of mutant mRNA transcripts may be contributory. Several mechanisms underlie the variable phenotype associated with the R1315C mutation. The potential utility of VWFpp as an independent marker of VWF biosynthesis and release warrants further research.

Joint health and functional ability in children with haemophilia who receive intensive replacement therapy

Joint physical examination is an important outcome in haemophilia; however its relationship with functional ability is not well established in children with intensive replacement therapy. Boys aged 4-16 years were recruited from two European and three North American treatment centres. Joint physical structure and function was measured with the Haemophilia Joint Health Score (HJHS) while functional ability was measured with the revised Childhood Health Assessment Questionnaire (CHAQ₃₈. Two haemophilia-specific domains were created by selecting items of the CHAQ₃₈ that cover haemophilia-specific problems. Associations between CHAQ, HJHS, cumulative number of haemarthroses and age were assessed. A total of 226 subjects - mean 10.8 years old (SD 3.8) - participated; the majority (68%) had severe haemophilia. Most severe patients (91%) were on prophylactic treatment. Lifetime number of haemarthroses [median=5; interquartile range (IQR)=1-12] and total HJHS (median = 5; IQR=1-12) correlated strongly (ρ = 0.51). Total HJHS did not correlate with age and only weakly (ρ=-0.19) with functional ability scores (median=0; IQR=-0.06-0). Overall, haemarthroses were reported most frequently in the ankles. Detailed analysis of ankle joint health scores revealed moderate associations (ρ=0.3-0.5) of strength, gait and atrophy with lower extremity tasks (e.g. stair climbing). In this population, HJHS summating six joints did not perform as well as individual joint scores, however, certain elements of ankle impairment, specifically muscle strength, atrophy and gait associated significantly with functional loss in lower extremity activities. Mild abnormalities in ankle assessment by HJHS may lead to functional loss. Therefore, ankle joints may warrant special attention in the follow up of these children.

Towards comprehensive care in transition for young people with haemophilia

  In the last two decades, the transition from paediatric to adult care has received increasing attention. Health care professionals have become more aware of the unique needs of adolescents and young adults with chronic illnesses and efforts have been made to support youth through this challenging time of change. For patients with haemophilia and their families, there is little evidence regarding best practice for transition of care. We reviewed the transition literature and current guidelines for transition for patients with haemophilia. We advocate that comprehensive haemophilia care includes a conscientious approach to transition of care that should start in early adolescence and be developmentally sensitive. In considering the needs of patients and parents, we must engage both paediatric and adult health care providers to make the transfer smooth and ensure the best care possible during this time.

Meeting unmet needs in inhibitor patients

For patients with haemophilia, the development of inhibitors complicates treatment, and inhibitor patients may thus have a range of unmet needs. Although successful inhibitor eradication will render patients responsive to factor replacement therapy, with potentially beneficial effects on long-term outcomes, this may not always be possible. Physicians treating inhibitor patients should aim to achieve reliable control of bleeding episodes, and the prevention of joint disease should also be a priority. Patients with high-titre inhibitors require therapy with bypassing agents--recombinant activated factor VII (rFVIIa) or a plasma-derived activated prothrombin complex concentrate (pd-APCC)--for the treatment of bleeding. When treating joint haemorrhage in inhibitor patients, both aggressive treatment of intercurrent joint bleeds and prophylaxis should be considered, although evidence is needed as to whether prophylaxis with bypassing agents can significantly delay/prevent the development of osteochondral changes in patients with inhibitors. Despite physicians' best efforts, joint disease may ultimately occur in inhibitor patients, and in such instances optimizing treatment, of both early and late stages, is important. There is no single therapeutic modality for dealing with the various treatment challenges posed by inhibitor patients, but overall goals should be to improve quality of life, with the provision of cost-effective care that aims to maintain physical function.

Quantitation of bleeding symptoms in children with von Willebrand disease: use of a standardized pediatric bleeding questionnaire

SUMMARY BACKGROUND

Excessive bruising and mucocutaneous bleeding are frequent presenting symptoms in childhood. A detailed bleeding history can distinguish children who may have an inherited bleeding disorder from those who are normal. There is a lack of standardization of such history taking in pediatric practise.

OBJECTIVES

To assess the performance of a Pediatric Bleeding Questionnaire (PBQ), an adaptation of a standardized adult bleeding questionnaire and score that includes pediatric-specific bleeding symptoms, in a cohort of children with von Willebrand disease (VWD).

PATIENTS/METHODS

Bleeding scores were determined by interview, for children with a previous diagnosis of VWD and a control group of unaffected siblings.

RESULTS

Bleeding scores were obtained for 100 children with VWD, median age 10.9 years (range, 0.8-17.8 years), and 21 unaffected siblings. Median bleeding score in children with VWD was 7.0 (range, 0-29) and in the control group was 0 (range, -1-2). Bleeding score varied within and between each VWD type: definite type 1, n = 40, median, 9.0 (range, 2-18); possible type 1, n = 38, median, 2.0 (0-15); type 2, n = 6, median, 14.0 (3-17); and type 3, n = 16, median, 12.0 (4-29). Bleeding scores in affected children correlated with age (Spearman's correlation coefficient, 0.35; P = 0.0004). The most frequent clinically significant bleeding symptoms were surgical bleeding, bleeding after tooth extraction and menorrhagia. Post-circumcision bleeding, cephalohematoma, macroscopic hematuria and umbilical stump bleeding were clinically significant in 32% (of circumcised males), 4%, 4% and 3% of children, respectively.

CONCLUSIONS

The PBQ provides a standardized quantitation of bleeding severity in children with VWD.

Comparative pharmacokinetics of plasma- and albumin-free recombinant factor VIII in children and adults: the influence of blood sampling schedule on observed age-related differences and implications for dose tailoring

BACKGROUND

Dose tailoring of coagulation factors requires reliably estimated and reproducible pharmacokinetics (PK) in the individual patient.

OBJECTIVES

To investigate the contribution of both biological and methodological factors to the observed variability of factor VIII (FVIII) PK, with the focus on differences between children and adults, and to examine the implications for dosing.

PATIENTS

Data from 52 1-6-year-old and 100 10-65-year-old patients with hemophilia A (FVIII < or = 2 IU dL(-1)) in three clinical studies were included.

RESULTS

In vivo recovery was lower, weight-adjusted clearance was higher and FVIII half-life was on average shorter in children than in adults. However, a reduced blood sampling schedule for children was estimated to account for up to one half of the total observed differences. Intrapatient variance in PK was smaller than interpatient variance in 10-65-year-olds. Age and ratio of actual to ideal weight only showed weak relationships with PK parameters. Variance in PK caused large variance in the calculated dose required to maintain a target FVIII trough level during prophylactic treatment.

CONCLUSION

Differences in blood sampling schedules should be taken into account when results from different PK studies are compared. However, even with this consideration, PK cannot be predicted from observable patient characteristics but must be determined for the individual. Because the influence of reducing the blood sampling was minor in comparison to the true variance between patients, a reduced blood sampling protocol can be used. Low intrapatient variability supports the use of PK measurements for dose tailoring of FVIII.

Break-through bleeding in relation to predicted factor VIII levels in patients receiving prophylactic treatment for severe hemophilia A

BACKGROUND

The role of prophylactic factor VIII (FVIII) to decrease hemophilic bleeding and arthropathy is well established. The rationale for this strategy is to convert patients with severe hemophilia A to a moderate clinical phenotype by reducing time spent with a FVIII level <1 IU dL(-1). Studies to date, however, have not demonstrated a strong link between FVIII level and the bleeding rate.

OBJECTIVES

To assess the effect of FVIII level on break-through bleeding in patients with severe hemophilia A on prophylaxis.

PATIENTS/METHODS

This study analysed data from 44 patients aged 1-6 and 99 patients aged 10-65 years with severe hemophilia A (FVIII <1 IU dL(-1)) who were treated with prophylactic FVIII as part of clinical studies assessing pharmacokinetics, safety and efficacy of a recombinant FVIII (Advate). Each patient had pharmacokinetic measurements and FVIII infusions recorded, and these were used to calculate time spent with a FVIII below 1, 2 and 5 IU dL(-1).

RESULTS

The data demonstrate that increasing time with a FVIII below 1 IU dL(-1) is associated with increased total bleeds and hemarthroses. Lack of adherence to the intended frequency of FVIII infusion was the most important determinant of low FVIII and increased bleeding. In children aged 1-6 years, the rate of bleeding was also influenced by FVIII half-life and clearance.

CONCLUSIONS

These data have important implications for the management of patients with severe hemophilia.

Plasma and albumin-free recombinant factor VIII: pharmacokinetics, efficacy and safety in previously treated pediatric patients

BACKGROUND

The pharmacokinetics of factor VIII replacement therapy in preschool previously treated patients (PTPs) with hemophilia A have not been well characterized.

OBJECTIVES

To assess the pharmacokinetics, efficacy and safety of a plasma-free recombinant FVIII concentrate, ADVATE [Antihemophilic Factor (Recombinant), Plasma/Albumin-Free Method, rAHF-PFM], in children < 6 years of age with severe hemophilia.

PATIENTS/METHODS

Fifty-two boys, one girl, mean (+/- SD) age 3.1 +/- 1.5 years and >or= 50 days of prior FVIII exposure, were enrolled in a prospective study of ADVATE rAHF-PFM at 23 centers.

RESULTS

The mean terminal phase half-life (t(1/2)) was 9.88 +/- 1.89 h, and the mean adjusted in vivo recovery (IVR) was 1.90 +/- 0.43 IU dL(-1) (IU kg(-1))(-1). Over the 1-6-year age range, t(1/2) of rAHF-PFM increased by 0.40 h year(-1). IVR increased by 0.095IU dL(-1)(IU kg(-1))(-1) (kg m(-2))(-1) in relation to body mass index (BMI). Patients primarily received prophylaxis. Median (range) annual joint bleeds were 0.0 (0.0-5.8), 0.0 (0.0-6.1) and 14.2 (0.0-34.5) for standard prophylaxis, modified prophylaxis and on-demand treatment, respectively. Bleeds were managed in 90% (319/354) of episodes with one or two rAHF-PFM infusions; response was rated excellent/good in 93.8% of episodes. Over a median 156 exposure days, no FVIII inhibitors were detected and no related severe adverse events or unusual non-serious adverse events were seen.

CONCLUSIONS

Children < 6 years of age appear to have shorter FVIII t(1/2) and lower IVR values than older subjects. However, these parameters increased with age (t(1/2)) and BMI (adjusted IVR), respectively. rAHF-PFM was clinically effective and well tolerated, with no signs of increased immunogenicity in previously treated young children with hemophilia A.

Comparing two measures of quality of life for children with haemophilia: the CHO-KLAT and the Haemo-QoL

Disease-specific measures of quality of life (QoL) for children with haemophilia are now available for use in clinical studies [Haemophilia, 10, 2004, 9-16]. One of these measures, the Canadian Haemophilia Outcomes - Kids' Life Assessment Tool (CHO-KLAT), was developed in Canada with emphasis on the perspectives of children [Pediatr Blood Cancer, 47, 2006, 305-11; Haemophilia, 10, 2004, 34-43]. Another, the Haemo-QoL, was developed in Europe, with emphasis on the perspectives of clinicians [Haemophilia, 8, 2002, 47-54; Haemophilia, 10, 2004, 17-25]. While these two measures are unique and independent, researchers from both studies were collaboratively linked throughout development and testing. This study presents the results of a joint assessment of the two measures with respect to their strengths, limitations and unique contributions. The primary questions addressed were: 1 What is the relationship between the CHO-KLAT and the Haemo-QoL in terms of summary scores and item content? 2 What are the methodological strengths, limitations and unique contributions of each measure? We conducted a retrospective analysis of data from field testing of both measures. The analysis included a comparative assessment of the basic validity, reliability and items used in each measure. Overall, the CHO-KLAT and the Haemo-QoL are promising and valuable measures of QoL for children with haemophilia. Our analyses confirmed the basic psychometric properties of both tools, but identified some discrepancies between them. Additional data will allow for greater understanding of these discrepancies and lend clarity to how the tools should be used in clinical studies (separately or merged). The present recommendation is that the measures be run independently, but preferably concurrently in studies of children with haemophilia.

Definitions for haemophilia prophylaxis and its outcomes: The Canadian Consensus Study

The creation of acceptable standard definitions for terms used in the care and assessment of haemophilia patients has become increasingly important, as a growing number of international clinical studies have been initiated. The Delphi approach has been used in health research to reach consensus in large groups and can be used to develop definitions by using several iterations of surveys eliciting opinions from specialists in the field. Three consecutive surveys were designed based on the Delphi approach and distributed to specialist physicians, nurses and physiotherapists in order to develop definitions for seven haemophilia terms: 'primary prophylaxis', 'secondary prophylaxis', 'target joint', 'joint bleed', 'significant soft-tissue bleed', 'superficial soft-tissue bleed' and 'mucosal bleed'. Suggestions were solicited, compiled into a subsequent survey and fed back to the group to rank-order the importance of each suggested component of the definition. Final definitions were created using the top-ranked suggestions and sent back to the experts for approval. Five of the seven terms were highly endorsed with greater than 90% agreement. Some differences in agreement were found when analysed by profession. Haemophilia terms were successfully defined using the Delphi approach. Further refinement from members of the international haemophilia community will ensure that comprehensive standard definitions can be used in multicentre studies in the future.

Inhibitor treatment in haemophilias A and B: summary statement for the 2006 international consensus conference

Participants in an international conference on the management of haemophilia patients with inhibitors developed a jointly authored summary of the findings and conclusions of the conference. Current knowledge of the genetic and immunologic mechanisms underlying inhibitor development was briefly summarized. Concerning the purported treatment-related risk factors, conference participants commented on the limitations of the available evidence and the need for more rigorous prospective research in a fully genotyped population. Other clinical considerations discussed included the unproved utility of routine surveillance, the need for assay standardization, the management of acute bleeding and approaches to joint disease prophylaxis and immune tolerance induction (ITI). A number of issues were identified as needing further investigation in larger prospective studies, ideally through international cooperation. Such studies should enroll cohorts that have been scrupulously defined in terms of mutation status and treatment exposure. Finally, conference participants urged their colleagues to participate in the currently ongoing international trials of ITI.

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

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.

Tailored prophylaxis in severe hemophilia A: interim results from the first 5 years of the Canadian Hemophilia Primary Prophylaxis Study

BACKGROUND

Prophylactic treatment for severe hemophilia A is likely to be more effective than treatment when bleeding occurs, however, prophylaxis is costly. We studied an inception cohort of 25 boys using a tailored prophylaxis approach to see if clotting factor use could be reduced with acceptable outcomes.

METHODS

Ten Canadian centers enrolled subjects in this 5-year study. Children were followed every 3 months at a comprehensive care hemophilia clinic. They were initially treated with once-weekly clotting factor; the frequency was escalated in a stepwise fashion if unacceptable bleeding occurred. Bleeding frequency, target joint development, physiotherapy and radiographic outcomes, as well as resource utilization, were determined prospectively.

RESULTS

The median follow-up time was 4.1 years (total 96.9 person-years). The median time to escalate to twice-weekly therapy was 3.42 years (lower 95% confidence limit 2.05 years). Nine subjects developed target joints at a rate of 0.09 per person-year. There was an average of 1.2 joint bleeds per person-year. The cohort consumed on average 3656 IU kg(-1)year(-1) of factor (F) VIII. Ten subjects required central venous catheters (three while on study); no complications of these devices were seen. One subject developed a transient FVIII inhibitor. End-of-study joint examination scores--both clinically and radiographically--were normal or near-normal.

CONCLUSIONS

Most boys with severe hemophilia A will probably have little bleeding and good joint function with tailored prophylaxis, while infusing less FVIII than usually required for traditional prophylaxis.

Canadian multi-institutional survey of immune tolerance therapy (ITT) - experience with the use of recombinant factor VIII for ITT

Immune tolerance therapy (ITT) is currently the most effective approach to eradicate inhibitors in patients with haemophilia A. Limited evidence suggests that the use of plasma-derived factor VIII (pdFVIII) for ITT may be associated with a greater success rate than recombinant factor VIII (rFVIII). Analysis of ITT cases in Canada offered the opportunity to examine the success rate of using rFVIII for ITT, as rFVIII has been used almost exclusively for Canadian haemophilia A patients since 1994. The results of 32 patients from five haemophilia treatment centres were collated. Three patients continue on ITT. Of the 29 patients who completed ITT, 25 (86.2%) used rFVIII exclusively, and four used pdFVIII exclusively or pdFVIII followed by rFVIII. The initial FVIII dosing frequency was once per day in 72.4% of patients at an average dose of 98 U kg(-1) (range 50-200). Eight patients (25%) received one or more adjuvant therapies. The median duration of ITT was 1.1 years (mean 1.5 years, range 9 days to 6 years). The overall success rate of the 29 patients who completed ITT was 79.3% (23/29), which is comparable with the results of immune tolerance registries. Our results suggest that the success rate of ITT using rFVIII is not inferior to the results with pdFVIII.

Rituximab for congenital haemophiliacs with inhibitors: a Canadian experience

When a high titre inhibitor develops in a patient with haemophilia, attempts are made to eradicate it through immune tolerance induction therapy (ITI) involving the frequent and regular administration of factor, usually for months to years. ITI is successful in only two thirds of patients prompting investigators to explore alternate regimens to use in haemophiliacs failing conventional ITI. Rituximab is an anti-CD20 monoclonal antibody, which has shown promise in the treatment of B-cell-mediated disorders. We developed a protocol for the use of rituximab in haemophilia A (HA) patients failing conventional ITI or in those haemophiliacs where the likelihood of success of conventional ITI is poor. Patients receive 375 mg m(-2) of intravenous rituximab weekly for 4 weeks followed by monthly (up to 5 months) until inhibitor disappearance and establishment of normal FVIII pharmacokinetics (recovery and half-life). Patients are concurrently placed on recombinant FVIII (100 U kg(-1) day(-1)). We have placed five haemophiliacs (four children with severe HA, and one adult with mild HA) on this protocol. In three patients (two with severe HA and one with mild HA) inhibitors disappeared although in neither severe haemophiliac did FVIII pharmacokinetics completely normalize. The fourth patient had a significant drop in inhibitor titres although not a complete disappearance of the inhibitor. All four of these patients ceased bleeding following rituximab. The fifth patient had no response to rituximab. This non-responding patient was not placed on concurrent FVIII. Our five cases suggest that rituximab may hold promise in the eradication of inhibitors. Prospective randomized studies are required to determine the value of this agent in inhibitor management.