Identifying hemophilia B carriers: Utility of aPTT, factor IX levels and ratios of factor IX to other Vitamin K dependent factors.

INTRODUCTION: Diagnosing hemophilia B (HB) carrier status is important to manage bleeding in carriers and to prevent bleeding in potential offspring. Without a family history of hemophilia, diagnosing HB carrier status is challenging. Genetic testing is the gold-standard, however it is reserved for individuals with a high suspicion of carrier status. AIMS: To describe the distribution of activated partial thromboplastin time (aPTT) and factor IX coagulant (FIX:C) levels in HB carriers and assess the ratio of FIX:C to other Vitamin K dependent factors (FII:C, FVII:C, FX:C) as an indicator of HB carrier status. METHODS: In this retrospective, single-centre cohort study, subjects were included if they were obligate or genetically proven HB carriers. Distributions of aPTT and FIX:C were described and the relationship between FIX:C levels in carriers and severity of familial HB was analysed. Ratios of FIX:C to FII:C, FVII:C, FX:C were calculated. RESULTS: Seventy-two female HB carriers (median age: 34 years; IQR 24-43) were included. Median aPTT and FIX:C levels were 33.0 s [IQR 30.0-37.0] and 57 IU/dL [IQR 43-74]. Fifteen carriers (21%) had mild HB (FIX:C levels of 10-40 IU/dL). FIX:C levels trended higher in carriers of mild HB versus carriers of moderate/severe HB. In six carriers, the median ratio of FIX:C to other Vitamin K dependent factors was 0.44, with 92% of ratios being ≤ 0.75. CONCLUSION: aPTT and FIX:C levels were unreliable in diagnosing HB carrier status. A low ratio of FIX:C to other Vitamin K dependent factors may be a useful marker of HB carrier status.

Unravelling the effect of blood group on FVIII:C levels and response to DDAVP in 20 males with a single genotype (Twillingate Variant) causing Haemophilia A.

INTRODUCTION: The genetic variant responsible for haemophilia A (HA) significantly impacts endogenous coagulant factor VIII (FVIII:C) level, thus impacting DDAVP responsiveness. Blood group (BG) also impacts FVIII:C levels, but this is difficult to evaluate in a genetically heterogeneous population. Canada has a large cohort of mild-moderate HA due to a single point variant: c.6104T>C, p.Val2035Ala-the Twillingate variant. AIM: To evaluate the impact of BG on endogenous FVIII:C levels and DDAVP responsiveness in a single genotype of mild-moderate HA. METHODS: This was a retrospective, single-centre study. BG and FVIII:C levels were obtained for males with the Twillingate variant. One-hour absolute and fold increases in FVIII:C post-DDAVP were calculated. T-tests and Mann-Whitney U tests were used to compare FVIII:C levels and DDAVP challenge variables between individuals according to BGs (O vs. non-O). RESULTS: Twenty males were included. There were significant differences between BGs (O vs. non-O) in their lowest FVIII:C level at age <12 years (medians: 0.05 vs. 0.08 IU/mL; P = .05). Fifteen subjects underwent DDAVP challenges. Mean 1-h FVIII:C were 0.29 (O BG) versus 0.41 IU/mL (non-O BG); P = .04. There were no significant differences between BGs (O vs. non-O) in mean absolute FVIII:C increase (0.20 vs. 0.27 IU/mL; P = .10) and FVIII:C fold increase (3.3-fold vs. 3.8-fold; P = .51). CONCLUSION: In HA subjects with an identical genotype, BG significantly impacts baseline FVIII:C levels and FVIII:C levels post-DDAVP, but does not impact absolute and fold increases in FVIII:C with DDAVP.

Moderate-intensity aerobic exercise vs desmopressin in adolescent males with mild hemophilia A: a randomized trial.

Persons with mild hemophilia A (HA) may use intranasal desmopressin prior to sports participation. Desmopressin is expensive and can cause vomiting, headache, palpitation, and occasionally seizures. Our group has previously documented a 2.3-fold increase in factor VIII activity (FVIII:C) in adolescents with mild HA after moderate-intensity aerobic exercise. Herein, we report principal findings of a randomized trial of intranasal desmopressin vs a standardized, moderate-intensity aerobic exercise regimen in adolescents with mild HA. Our primary objective was to compare the change in FVIII:C associated with these 2 interventions. We also examined changes in hemostatic parameters arising from their sequential administration. The study was conducted simultaneously at the Hospital for Sick Children, Canada, and Nationwide Children's Hospital, USA. Thirty-two eligible male adolescents (mean age ± standard deviation: 16.1 ± 2.6 years) with mild HA (mean baseline FVIII:C: 27.9% ± 18.4%) were randomized to 1 of 4 study arms (desmopressin followed by exercise, desmopressin alone, exercise followed by desmopressin, and exercise alone). Blood work was obtained at baseline and at 3 subsequent time-points. Participants randomized to exercise cycled on an ergometer for approximately 12 minutes, with the final 3 minutes at 85% of their predicted maximum heart rate. Standard weight-based dosing of desmopressin was used. Mean immediate increase in FVIII:C was 1.7-fold with exercise compared with 1.9-fold with desmopressin (noninferiority, P = .04). Exercise-induced improvement in hemostatic parameters including FVIII:C was brief compared with more sustained improvements seen with desmopressin. More than 60% of participants randomized to receive both exercise and desmopressin achieved normal (>50%) FVIII:C, 75 and 135 minutes into the study protocol.

Excess weight gain in the paediatric bleeding disorders population: Impact of the COVID-19 Pandemic.

INTRODUCTION: The COVID-19 pandemic has resulted in lifestyle changes for children. The aim of this study was to evaluate the impact of the pandemic on weight/BMI in children with severe bleeding disorders. METHODS: We conducted a retrospective review of patients age 3-18 years with severe bleeding disorders on prophylactic therapy treated at SickKids Hospital (Toronto, Canada) between February 01, 2018 and March 31, 2021. We evaluated the following pre- and post-COVID variables: weight (kg), weight percentile, BMI (kg/m2 ), BMI percentile, HJHS score, and prophylactic dosing (units/kg). RESULTS: One hundred and four patients were included in the final analysis. Diagnoses were as follows:  haemophilia A (n = 92; 70.8%), haemophilia B (n = 17; 13.1%), type 3 von Willebrand disease (n = 11; 8.5%), the remainder were diagnosed with rare factor deficiencies.  Median interval time from pre-COVID measurements to latest follow-up was 12.4 months (IQR 10.32-14.52 months) during which there was a statistically significant increase in median weight percentile +5.75 centiles (from 63rd centile to 68.75th centile). There was a statistically significant increase in mean BMI of +1.03 kg/m2 (P = < .001) while median BMI percentile increased +8.82 centiles (from 53.9th centile to 62.72nd centile) and mean BMI percentile increased 3.42 centiles (from 57.5 centile to 60.9 centile). The group that gained the most weight centiles, BMI and BMI centiles were 5-14 years old. CONCLUSION: There was a trend to weight gain over the study period. More long-term data is required to evaluate the impact of this increase in weight and BMI on children with bleeding disorders.

A semiquantitative color Doppler ultrasound scoring system for evaluation of synovitis in joints of patients with blood-induced arthropathy.

BACKGROUND: Intra-articular bleeds in patients with inherited bleeding disorders lead to active synovitis which may progress to a chronic state over time. We explored the diagnostic value of color Doppler ultrasound in detecting synovitis in boys with bleeding disorders. RESULTS: Sixty boys with hemophilia and 3 boys with type 3 von Willebrand disease aged 5 to 18 years (median 12.3 years) were imaged by gray-scale and color Doppler ultrasound (US) in three centers (Beijing, China [n = 22], Guangzhou, China [n = 12] and Toronto, Canada [n = 29])) in this observational study. Images were independently reviewed by two radiologists blinded to clinical data using a subjective semi-quantitative scoring system and objective measurements of synovial thickness and vascularity. Inter-reader reliability for using subjective versus objective color Doppler US methods for assessing synovial vascularity was excellent for the subjective method and moderate/lower range of substantial for the objective method. Agreement between degree of vascularity on color Doppler and extent of synovial hypertrophy on gray-scale US was overall poor for Canada data and moderate for China data. Correlations between degree of vascularity on color Doppler and synovial hypertrophy on gray-scale US, and clinical constructs (total and itemized HJHS scores and total Pettersson X-ray scores) for assessment of blood-induced arthropathy were all poor. CONCLUSION: Color Doppler US is a valuable scoring method for evaluating reactive synovitis in joints of subjects with inherited bleeding disorders and holds potential for assessing post-bleed reactive synovitis once further information on its association with timing of the joint bleed becomes available in the literature.

Measuring the impact of hemophilia on families: Development of the Hemophilia Family Impact Tool (H-FIT).

INTRODUCTION: This study aimed to assess the impact of hemophilia on families, in the context of current and emerging hemostatic therapies, and explore the need for a hemophilia-specific tool targeted at parents of boys aged <4 years. A secondary aim was to develop and validate the new tool. METHODS: Focus groups were conducted with parents of boys with hemophilia and hemophilia health care providers at Canadian hemophilia treatment centers (HTCs) to review the relevance of the Pediatric Quality of Life Family Impact Module (PedsQL-FIM); a novel questionnaire was developed by identifying core themes expressed. This questionnaire, the Hemophilia Family Impact Tool (H-FIT) was validated in a sample of parents of boys with hemophilia relative to the PedsQL-FIM. RESULTS: Seven focus groups were conducted at four HTCs, generating themes specific to hemophilia not covered by the PedsQL-FIM, suggesting that a new tool be developed (the H-FIT). In the validation phase, 54 parents completed the H-FIT and PedsQL-FIM. The H-FIT had a strong correlation with the PedsQL-FIM across all ages (r = 0.79; P < .0001) and a moderate correlation for parents of boys aged <7 years (r = 0.64; P = .0007). There was a significant difference between the mean H-FIT scores for parents of boys using extended half-life factor (68.1; standard deviation [SD]=14.2) compared to standard half-life factor (54.7; SD=18.4; P = .04). CONCLUSION: A novel, disease-specific tool, the H-FIT, has been developed to measure the impact of hemophilia on families. The H-FIT has good preliminary measurement properties and may be responsive to changes in therapy associated with a decreased burden of administration.

Updating the Canadian Hemophilia Outcomes-Kids' Life Assessment Tool (CHO-KLAT) in the era of extended half-life clotting factor concentrates.

INTRODUCTION: The purpose of this study was to review and update the content of the Canadian Hemophilia Outcomes-Kids' Life Assessment Tool version 2.0 (CHO-KLAT), in the context of extended half-life (EHL) factor concentrates (FCs) and to establish the validity and reliability of the updated CHO-KLAT. METHODS: Focus groups were conducted with boys with hemophilia, their parents, and health care providers across Canada to review the CHO-KLAT v2.0 and determine if any modifications were required. The validity of the revised CHO-KLAT (version 3.0) was then determined in a sample of boys with hemophilia and their parents by calculating its correlation with the Pediatric Quality of Life Core Module (PedsQL-Core). Test-retest reliability was assessed using an intraclass correlation coefficient (ICC). RESULTS: Thirteen focus groups at 5 pediatric hemophilia treatment centers (HTCs) (n = 71) resulted in 19 changes to the CHO-KLAT v2.0, generating a revised 40-item CHO-KLAT, the CHO-KLAT v3.0. Thirty-five boys with hemophilia (median age, 14; range, 7-17 years) and 47 parents participated in the validation of the CHO-KLAT v3.0. There was a moderate correlation between the CHO-KLAT v3.0 child self-report and PedsQL-Core (r = 0.56, P = .01), and a strong correlation between the CHO-KLAT v3.0 parent-proxy and PedsQL-Core (r = .79, P = .0007). The test-retest reliability ICC was 0.90 for the child self-report CHO-KLAT v3.0 and 0.68 for the parent-proxy CHO-KLAT v3.0. CONCLUSION: The CHO-KLAT v3.0 is a reliable and valid child-centric tool that effectively measures health-related quality of life in boys with hemophilia who are receiving standard half-life or EHL FCs.

Shortening the paediatric Haemophilia Activities List (pedHAL) based on pooled data from international studies.

INTRODUCTION: The paediatric Haemophilia Activities List (pedHAL) was developed to measure activities and participation in children and youth with haemophilia. Results from international studies provide an opportunity to determine which items are universally important. AIM: The aim of this study was to determine which items of the pedHAL are redundant to construct a shorter version of the pedHAL. METHODS: This study is a cross-sectional multicentre secondary analysis on pooled data of published studies using the pedHAL (7 domains, 53 items, optimum score: 100) in children with haemophilia A/B aged 4-18 years. To identify redundant items, the following aspects were evaluated: floor and ceiling effects, proportions of missing and 'not applicable' responses, inter-item correlations, component loadings in an exploratory factor analysis, internal consistency and item-total correlations. RESULTS: Data on 315 patients with haemophilia from 6 studies were evaluated. Median age was 12.2 years) (range 4.0-18.0), 87.3% had severe haemophilia and 80.3% received prophylaxis. Median (IQR) pedHAL sum score was 96.7 (88.0-100). After a stepwise procedure, 31 items were removed, resulting in a pedHALshort of 22 items, representing all original 7 domains. Most remaining items belonged to the domains 'sitting/kneeling/standing' and 'functions of the legs'. The pedHALshort sum score was similar to the original pedHAL sum score, with small differences in 5 domains. CONCLUSION: This clinimetric study resulted in >50% reduction of the length of the pedHAL. The 22-item pedHALshort reduces patient burden and is expected to capture the information on activities and participation. The pedHALshort needs validation in other populations.

Measuring the impact of changing from standard half-life (SHL) to extended half-life (EHL) FVIII prophylaxis on health-related quality of life (HRQoL) in boys with moderate/severe haemophilia A: Lessons learned with the CHO-KLAT tool.

INTRODUCTION: In many countries, there is a shift from standard half-life (SHL) to extended half-life (EHL) clotting factor concentrates (CFCs). AIM: To describe the experience of switching from SHL to an EHL FVIII CFC and the impact of this on frequency of infusions, factor consumption, bleeding rates and HRQoL using the Canadian Hemophilia Kids' Life Assessment Tool (CHO-KLAT). METHODS: A retrospective chart review was conducted at a single haemophilia treatment centre in 2018 that included boys (ages: 4-18 years) with moderate/severe haemophilia A, without inhibitors, who switched from a SHL to an EHL FVIII CFC in the previous 2 years and for whom HRQoL data were available. RESULTS: The study cohort comprised 38 boys [mean (SD) age: 11.0 (3.4) years] with moderate (n = 5)/severe (n = 33) haemophilia A. The switch was associated with a 33% reduction in the number of weekly infusions from a median of 3.5 to 2.3 (P < .0001) and a 17% reduction in median FVIII consumption from 103 IU/kg/wk to 85.5 IU/kg/wk (P = .004). There was no significant change in annualized joint bleed rates or in CHO-KLAT scores. CONCLUSIONS: Despite documenting several benefits of switching to EHL FVIII (less infusions, lower factor consumption with no increase in bleeding), our study did not demonstrate any improvement in HRQoL. We conclude that either the current CHO-KLAT tool is not optimized to measure burden of treatment administration in boys with low bleed rates switching from SHL to EHL FVIII CFCs or that a reduction of 1.2 infusions/week does not result in a meaningful change in HRQoL.

Idiopathic pulmonary arterial hypertension - a unrecognized cause of high-shear high-flow haemostatic defects (otherwise referred to as acquired von Willebrand syndrome) in children.

Acquired von Willebrand syndrome (AVWS) is reported in high-flow high-shear congenital cardiac disorders. We hypothesized that the narrowed pulmonary vasculature in idiopathic pulmonary arterial hypertension (IPAH) may induce AVWS. We conducted a cross-sectional evaluation of children with IPAH. Patients with bleeding symptoms and/or laboratory abnormalities (thrombocytopenia, anomalies in coagulation screening tests) were tested in-depth for haemostatic defects. Fourteen children were followed with IPAH of which 8 were eligible. Four children exhibited abnormal bleeding scores (International Society on Thrombosis and Haemostasis Bleeding Assessment Tool: 3-5). All 8 patients showed very prolonged platelet function analyser (PFA)-100 closure times. Six children demonstrated either mild thrombocytopenia or low-normal von Willebrand factor (VWF) antigen (VWF:Ag) or VWF activity [mean (range), in iu/dl: VWF:Ag: 70 (61-91); VWF activity: 57 (34-70)]. Average VWF collagen binding capacity (VWF:CB) was 64 iu/dl (range: 53-123 iu/dl), with low-normal VWF activity/VWF:Ag or VWF:CB/VWF:Ag ratios occurring in five patients. All children had normal multimers distribution patterns. One patient underwent a lung transplantation, with normalization of haemostatic abnormalities post-surgery. Overall, 8 out of 14 children with IPAH had mild to moderate bleeding symptoms and/or laboratory abnormalities in keeping with AVWS. Normalization of the haemostatic defects following lung transplantation and lack of family history of bleeding attests to the acquired nature of their defects.

Online Peer-to-Peer Mentoring Support for Youth with Hemophilia: Qualitative Needs Assessment.

BACKGROUND: To support adolescents through transition from pediatrics to adult care, health care providers and families help teens gain knowledge and develop self-management skills. Peer mentoring can provide meaningful support and has been associated with improved health outcomes in patients with other chronic conditions. Peer mentoring is an appealing way to provide support, but it is imperative to consider the unique needs of adolescents to ensure its success. OBJECTIVE: The objective of our study was to identify the peer mentoring wants and needs of youth with hemophilia in order to guide the development of a new program. METHODS: In this qualitative study, we interviewed a convenience sample of youth with hemophilia from 2 Canadian hemophilia treatment centers. Two iterative cycles of audiorecorded, semistructured individual interviews were conducted. Descriptive statistics and content analyses were used to organize data into categories that reflected emerging themes. RESULTS: In total, we recruited 23 participants aged 12-20 years, with a mean age of 14.91 (2.57) years. When asked about program design, participants weighed the importance of flexibility in delivery (eg, Web-based, in person, text messaging [short message service]), content (eg, structured vs unstructured), frequency of sessions, and length of the program. Participants identified some potential challenges such as scheduling issues, comfort level for disease discussion, and discordant mentor-mentee personality types. The program was viewed as a positive medium for connecting peers with hemophilia. CONCLUSIONS: Adolescents with hemophilia expressed interest in a peer mentoring program and provided valuable insight that will be applied in the development of a peer mentoring program for youth with hemophilia.

Don't Push Your Luck! Educational Family Board (Not Bored) Game for School-Age Children Living with Chronic Conditions.

PURPOSE: Children who are living with chronic conditions may be supported in self-care through enjoyable active learning and family social processes. This research focused on development and evaluation of "Don't Push Your Luck!", an educational board game designed to inspire family discussion about chronic conditions, and help affected children learn about self-care choices and consequences. DESIGN AND METHODS: Mixed-method research was conducted with families from one outpatient Cystic Fibrosis Clinic and four Hemophilia Treatment Centres in Canada and United States (N=72). In phase I, board game prototype and questionnaires were refined with affected boys, siblings, and parents living with hemophilia (n=11), compared with families living with cystic fibrosis (n=11). In phase II, final board game was evaluated with families living with hemophilia (n=50). Data collection included pre-post-game questionnaires on decision-making and Haemo-QoL Index©, and post-game enjoyment. Analysis included descriptive statistics, inferential statistics (non-parametric), and qualitative themes. RESULTS: Findings revealed this game was an enjoyable and effective resource to engage families in self-care discussions. Key themes included communication, being involved, knowing, decisions and consequences, and being connected. Qualitative and quantitative findings aligned. Statistical significance suggests the game enhanced family engagement to support decision-making skills, as parents identified that the game helped them talk about important topics, and children gained insight regarding family supports and self-care responsibility. CONCLUSIONS: This board game was an effective, developmentally appropriate family resource to facilitate engagement and conversation about everyday life experiences in preparation for self-care. PRACTICE IMPLICATIONS: There is promising potential to extend this educational family board game intervention with a greater range of school-age children and families living with chronic conditions.

Impact of aerobic exercise on haemostatic indices in paediatric patients with haemophilia.

UNLABELLED: This study investigated the impact of aerobic exercise on laboratory assessments of haemostatic activity in boys (5-18 years of age) with haemophilia A (HA) or B (HB), examining the hypothesis that laboratory coagulation parameters temporarily improve with exercise. Thirty subjects meeting eligibility criteria (19 HA; 11 HB; mean age: 12.8 years) were invited to participate. They underwent a replacement factor washout period and were advised against strenuous activity for three days prior to the planned intervention. At study visit, baseline blood samples were drawn prior to exercise on a stationary cycle ergometer, aiming to attain 3 minutes (min) of cycling at 85 % of predicted maximum heart rate. Blood work was repeated 5 min (t5) and 60 min (t60) post exercise completion. Samples were assessed for platelet count (PC), factor VIII activity ( FVIII: C), von Willebrand antigen (VWF:Ag), ristocetin cofactor activity (VWF:RCo) and platelet function analysis (PFA-100); maximum rate of thrombus generation (MRTG) in blood was measured via thromboelastography and plasma peak thrombin generation (PTG) via calibrated automated thrombography. Mean duration of exercise was 13.9 (± 2.6) min. On average, t5 samples showed significant elevation, relative to baseline in PC, FVIII:C, VWF:Ag, VWF:RCo and PTG, while FVIII: C, VWF:Ag, VWF:RCo and MRTG were significantly elevated in t60 samples. Within the cohort, participants with severe HA showed no change in FVIII: C levels with exercise. The greatest improvement in haemostatic indices was observed in post-adolescent males with mild-moderate HA, who thus represent the group most likely to benefit from a reduction of bleeding risk in the setting of exercise.