Clinical and treatment characteristics of infants and toddlers less than 2 years of age with hemophilia.

ABSTRACT: Infants and toddlers (ITs) with hemophilia have unique bleeding features. Factor prophylaxis has been shown to decrease the risk of intracranial hemorrhage (ICH), which supports recommendations to begin at a young age. Clinical and demographic characteristics were analyzed for 883 ITs ≤2 years old with hemophilia A and B, seen at US Hemophilia Treatment Centers and enrolled in the Community Counts Registry, a surveillance program of the Centers for Disease Control and Prevention. ICH in the first 2 years of life was seen in 68 of 883 (7.7%) ITs, of whom 8 of 68 (11.8%) were on continuous prophylaxis at the time of ICH. ITs in this study usually started prophylaxis within the first year of life (mean, 10.3 months), with earlier ages of prophylaxis initiation in later birth cohorts in ITs with hemophilia A. Compared with those without a family history (FH) of hemophilia, known positive FH of hemophilia was associated with earlier age of diagnosis (P ≤ .0001) and decreased rates of vaginal delivery (P = .0006). The use of factor VIII mimetics and extended half-life clotting factor prophylaxis increased with later birth cohorts for ITs with hemophilia A and B. The study highlights that ICH rates in ITs with hemophilia remains substantial and underscores the need for further research to identify modifiable risk factors to prevent ICH by earlier diagnosis and initiating prophylaxis early, even within the first month of life.

Management of pregnancy and delivery in congenital fibrinogen disorders: communication from the ISTH SSC Subcommittee on Factor XIII and Fibrinogen.

Congenital fibrinogen disorders (CFDs) are a heterogeneous group of rare congenital quantitative and/or qualitative fibrinogen deficiencies. The spectrum of molecular anomalies is broad, leading to several subtypes of fibrinogen disorders (ie, afibrinogenemia, hypofibrinogenemia, dysfibrinogenemia, and hypodysfibrinogenemia). Pregnancy in women with CFDs is a high-risk clinical situation, with an increased tendency for miscarriages, bleeding, and thrombosis. Even though it is well established that management of such pregnancies requires a multidisciplinary approach involving specialists (hematologists and maternal/fetal medicine experts with expertise in the management of inherited bleeding disorders), specific guidelines are lacking. In this International Society on Thrombosis and Haemostasis (ISTH) Scientific and Standardization Committee communication, we aim to propose an expert consensus opinion with literature evidence where available on the strategy for management of pregnancy, delivery, and puerperium in CFDs.

Hemostasis in the Pregnant Woman, the Placenta, the Fetus, and the Newborn Infant.

The hemostasis system is composed of procoagulant, anticoagulant, and fibrinolytic proteins that interact with endothelial and blood cells and with each other in a complex system of checks and balances to maintain blood flow while preventing both hemorrhage and thrombosis. Pregnancy is a unique physiological state in which biological alterations predispose both mother and fetus to both bleeding and clotting. The placenta is a vascular interface for maternal and fetal blood exchange which predisposes the mother to hemorrhage. Maternal hemostasis presents a compensatory hypercoagulability including elevated factor VIII, von Willebrand factor, fibrinogen and thrombin generation, decreased thrombin regulation with resistance to activated protein C and decreased free protein S, and decreased fibrinolysis with increased plasminogen activator inhibitors. The placental vascular surface is of fetal trophoblastic origin that derives many characteristics of endothelium but differs in that tissue factor is constitutively expressed. Ontogeny of fetal hemostasis is characteristic. Platelets, von Willebrand factor, factor VIII, and fibrinogen are expressed and mature early in gestation, while vitamin K-dependent and contact factors exhibit delayed development. The fetal hemostatic system has a decreased capacity to generate or regulate thrombin, resulting in a fragile balance with little capacity to compensate under stress conditions, particularly in the infant born prematurely. Dysfunction of the maternal/placental/fetal unit gives rise to gestational disorders including preeclampsia, fetal growth restriction, placental abruption, and premature delivery. Knowledge of normal hemostasis levels and function are critical to evaluate bleeding or clotting syndromes in the pregnant woman and her fetus or newborn infant.

Long-term prophylaxis: what are our options and how to define success?

Currently, we are at an enviable place in hemophilia treatment. Although full prophylaxis with standard half-life recombinant or plasma-derived factor concentrates has been definitively shown to be inadequate for full protection against bleeding and arthropathy, a number of novel therapies with improved hemostatic enhancement are clinically available or in promising clinical trials. In order to compare outcomes among a number of very efficacious therapies, it is necessary to have sensitive tools employed in long-term follow-up for several years for participants with no or minimal joint disease. The tool kit must be comprehensive, with outcomes of bleeding, factor level restoration or hemostatic capacity, joint structure, joint function, pain, quality of life, and patient satisfaction. This article reviews the history of prophylaxis, the promise of emerging therapies, and the sensitive tools used to assess long-term efficacy for joint structure and function.

Comorbidities, Health-Related Quality of Life, Health-care Utilization in Older Persons with Hemophilia-Hematology Utilization Group Study Part VII (HUGS VII).

Purpose: We compare the impact of hemophilia on comorbidities, joint problems, health-related quality of life (HRQoL) and health-care utilization between two age groups: 40-49 years and ≥50 years. Patients and Methods: The HUGS VII study recruited persons with hemophilia A or B age ≥40 years. Participants completed surveys to collect data on sociodemographic and clinical characteristics, hemophilia treatment regimen, pain, joint problems, comorbidities, HRQoL, depression and anxiety, at baseline and 6-months later. Clinical chart reviews documented hemophilic severity and treatment. Results: The sample includes 69 males, 65.2% aged ≥50 years, 75.4% with hemophilia A. Individuals ≥50 years were more likely to have mild or moderate hemophilia (68.9% vs 41.7%, P = 0.03) than those 40-49 years old. Among persons with mild/moderate hemophilia, those ≥50 years old reported a higher rate of joint pain (83.9% vs 70.0%, P = 0.34 at baseline, 91.3% vs 57.1%, P = 0.06 at follow up) or range of motion limitation (73.3% vs 60.0%, P = 0.43 at baseline, 73.9% vs 28.6%, P = 0.04 at follow up) than the younger group. Compared to the younger group, the older group reported fewer emergency room visits (4.5% vs 21.7%, P = 0.03), and physical therapy visits (15.9% vs 43.5%, P = 0.01) at baseline. The sample depression rate was 85.7%, but the differences among the age groups were not significant. The mean covariate-adjusted EQ-5D index score was lower in older persons (0.77 vs 0.89, P = 0.02). Conclusion: Older persons with hemophilia in this sample are over-represented by individuals with mild/moderate disease, potentially due to premature death among those with severe disease. Although this group included a larger proportion of individuals with mild disease than the younger group, they experienced lower quality of life, more comorbidities both of aging and of hemophilic arthropathy, and lower rates of health-care utilization.

Novel characteristics of soluble fibrin: hypercoagulability and acceleration of blood sedimentation rate mediated by its generation of erythrocyte-linked fibers.

Soluble fibrin (SF) in blood consists of monomers lacking both fibrinopeptides A with a minor population in multimeric clusters. It is a substantial component of isolated fibrinogen (fg), which spontaneously self-assembles into protofibrils progressing to fibers at sub-physiologic temperatures, a process enhanced by adsorption to hydrophobic and some metal surfaces. Comparisons of SF-rich (FR) and SF-depleted (FD) fg isolates disclosed distinct molecular imprints of each via an adsorption/desorption procedure using gold surfaced silica microplates. Accelerated plasminogen activator-induced lysis and decreased stiffness (G') of thrombin-induced FR fg clots were revealed by thomboelastography. Erythrocyte sedimentation (ESR) in afibrinogenemic plasma (Hematocrit 25-33%) was accelerated by FR fg nearly threefold that of FD fg. Stained smears disclosed frequent rouleaux formations and fibers linking stacked erythrocytes in contrast to no rouleaux by FD fg. Rouleaux formations were more pronounced at 4 °C than at ambient temperatures and at fiber-membrane contacts displayed irregular, knobby membrane contours. One of several FR fg isolates also displayed incomplete fiber networks in cell-free areas. What is more, pre-mixing FR fg with each of three monoclonal IgG anti-fg antibodies at 1.5 mol/mol fg, that inhibited fibrin polymerization, prevented rouleaux formation save occasional 2-4 erythrocyte aggregates. We conclude that spontaneously generated SF fibers bound to erythrocytes forming intercellular links culminating in rouleaux formation and ensuing ESR acceleration which in clinical settings reflects hypercoagulability. Also, the results can explain the reported fg binding to erythrocytes via ligands such as CD47, stable in vivo RBC aggregates in capillaries, and red areas of pathologic thrombi.

The Hemophilia Joint Health Score version 2.1 Validation in Adult Patients Study: A multicenter international study.

Background: The Hemophilia Joint Health Score (HJHS) was developed and validated to detect arthropathy in children. Additional evidence is required to show validity in adults. We studied the convergent and discriminant construct validity of the HJHS version 2.1(HJHSv2.1) in adults with hemophilia. A secondary aim was to define age-related normative adult HJHSv2.1 reference values. Methods: We studied 192 adults with hemophilia, and 120 healthy adults in four age-matched groups-18 to 29, 30 to 40, 41 to 50, and >50 years-at nine centers. Trained physiotherapists scored the HJHS and World Federation of Hemophilia (WFH) joint score. Health history, the Functional Independence Scale of Hemophilia (FISH), Hemophilia Activities List (HAL), and Short-Form McGill Pain Questionnaire (SF-MPQ) were also collected. Results: The median age was 35.0 years. Of participants with hemophilia, 68% had severe, 14% moderate, and 18% mild disease. The HJHS correlated strongly with WFH score (Spearman's rho [rs ] = .95, P < .001). Moderate correlations were seen between the FISH (rs  = .50, P < .001) and SF-MPQ Present Pain Intensity (rs  = .50, P < .001), while a modest correlation was found with the HAL (rs  = -.37, P < .001). The HJHS significantly differentiated between age groups (Kruskal-Wallis T = 35.02, P < .001) and disease severity in participants with hemophilia. The HJHS had high internal reliability (Cronbach's α = .88). We identified duration of swelling as a redundant item in the HJHS. Conclusions: The HJHS shows evidence of strong convergent and discriminant construct validity to detect arthropathy in adults with hemophilia and is well suited for use in this population.

Effect of Anticoagulant Therapy for 6 Weeks vs 3 Months on Recurrence and Bleeding Events in Patients Younger Than 21 Years of Age With Provoked Venous Thromboembolism: The Kids-DOTT Randomized Clinical Trial.

Importance: Among patients younger than 21 years of age, the optimal duration of anticoagulant therapy for venous thromboembolism is unknown. Objective: To test the hypothesis that a 6-week duration of anticoagulant therapy for provoked venous thromboembolism is noninferior to a conventional 3-month therapy duration in patients younger than 21 years of age. Design, Setting, and Participants: Randomized clinical trial involving 417 patients younger than 21 years of age with acute, provoked venous thromboembolism enrolled at 42 centers in 5 countries from 2008-2021. The main exclusions were severe anticoagulant deficiencies or prior venous thromboembolism. Patients without persistent antiphospholipid antibodies and whose thrombi were resolved or not completely occlusive upon repeat imaging at 6 weeks after diagnosis underwent randomization. The final visit for the primary end points occurred in January 2021. Interventions: Total duration for anticoagulant therapy of 6 weeks (n = 207) vs 3 months (n = 210) for provoked venous thromboembolism. Main Outcomes and Measures: The primary efficacy and safety end points were centrally adjudicated symptomatic recurrent venous thromboembolism and clinically relevant bleeding events within 1 year blinded to treatment group. The primary analysis was noninferiority in the per-protocol population. The noninferiority boundary incorporated a bivariate trade-off that included an absolute increase of 0% in symptomatic recurrent venous thromboembolism with an absolute risk reduction of 4% in clinically relevant bleeding events (1 of 3 points on the bivariate noninferiority boundary curve). Results: Among 417 randomized patients, 297 (median age, 8.3 [range, 0.04-20.9] years; 49% female) met criteria for the primary per-protocol population analysis. The Kaplan-Meier estimate for the 1-year cumulative incidence of the primary efficacy outcome was 0.66% (95% CI, 0%-1.95%) in the 6-week anticoagulant therapy group and 0.70% (95% CI, 0%-2.07%) in the 3-month anticoagulant therapy group, and for the primary safety outcome, the incidence was 0.65% (95% CI, 0%-1.91%) and 0.70% (95% CI, 0%-2.06%). Based on absolute risk differences in recurrent venous thromboembolism and clinically relevant bleeding events between groups, noninferiority was demonstrated. Adverse events occurred in 26% of patients in the 6-week anticoagulant therapy group and in 32% of patients in the 3-month anticoagulant therapy group; the most common adverse event was fever (1.9% and 3.4%, respectively). Conclusions and Relevance: Among patients younger than 21 years of age with provoked venous thromboembolism, anticoagulant therapy for 6 weeks compared with 3 months met noninferiority criteria based on the trade-off between recurrent venous thromboembolism risk and bleeding risk. Trial Registration: ClinicalTrials.gov Identifier: NCT00687882.

Emicizumab initiation and bleeding outcomes in people with hemophilia A with and without inhibitors: A single-center report.

BACKGROUND: Emicizumab, a bispecific antibody factor VIII mimetic, is approved for prophylaxis in hemophilia, and has different risks and side effects compared to factor VIII products. OBJECTIVE: To better understand the early impact of emicizumab on our patients at the University of Colorado Hemophilia and Thrombosis Center (UCHTC), we evaluated adverse reactions, factor prophylaxis overlap, and bleeding rates after starting emicizumab through a quality improvement project. PATIENTS/METHODS: A retrospective chart review and structured phone interview were conducted from June to September 2019 for all patients who had started emicizumab at the UCHTC. Data about emicizumab dosing, reactions, bleeding events, and bleeding treatment were collected in 68 children and adults (aged 0.55-79.8 years, on emicizumab a median 213 days; range, 51-1229 days) with hemophilia A (35.3% with past or current inhibitor). RESULTS: Adverse reactions were primarily skin reactions, with no anaphylactic reactions or thrombosis. Bleeding events, defined as pain or swelling treated with factor or supportive measures, demonstrated wide variability, with 25 of 68 experiencing zero bleeds and 5 of 68 experiencing >8 bleeds per year. The most prevalent bleed type was traumatic musculoskeletal bleeding. Bleeding events occurred more often in the first 10 weeks after starting emicizumab, but no time period was without bleeding events. The majority of patients were prescribed every-week or every-2-week dosing, but some had alternative dosing frequency. CONCLUSIONS: Real-world emicizumab use in our center was characterized by variations in prescribing practices and bleeding outcomes and lack of severe adverse reactions.

Musculoskeletal ultrasound in hemophilia: Results and recommendations from a global survey and consensus meeting.

INTRODUCTION: For persons with hemophilia, optimization of joint outcomes is an important unmet need. The aim of this initiative was to determine use of ultrasound in evaluating arthropathy in persons with hemophilia, and to move toward consensus among hemophilia care providers regarding the preferred ultrasound protocols for global adaptation. METHODS: A global survey of hemophilia treatment centers was conducted that focused on understanding how and why ultrasound was being used and endeavored to move toward consensus definitions of both point-of-care musculoskeletal ultrasound (POC-MSKUS) and full diagnostic ultrasound, terminology to describe structures being assessed by ultrasound, and how these assessments should be interpreted. Next, an in-person meeting of an international group of hemophilia health care professionals and patient representatives was held, with the objective of achieving consensus regarding the acquisition and interpretation of POC-MSKUS and full diagnostic ultrasound for use in the assessment of musculoskeletal (MSK) pathologies in persons with hemophilia. RESULTS: The recommendations were that clear definitions of the types of ultrasound examinations should be adopted and that a standardized ultrasound scoring/measurement system should be developed, tested, and implemented. The scoring/measurement system should be tiered to allow for a range of complexity yet maintain the ability for comparison across levels. CONCLUSION: Ultrasound is an evolving technology increasingly used for the assessment of MSK outcomes in persons with hemophilia. As adoption increases globally for clinical care and research, it will become increasingly important to establish clear guidelines for image acquisition, interpretation, and reporting to ensure accuracy, consistency, and comparability across groups.

Improvements in Communication and Coordination of Care in a Hemophilia Treatment Center.

INTRODUCTION: In response to the increasing complexity of care for patients with bleeding disorders, we established new clinical teams for our hemophilia treatment center (HTC). AIMS: We undertook a quality improvement project to improve the coordination and communication with our patients by establishing primary assignments of clinical staff to individual patients (primary teams). METHODS: A quality improvement project group was formed that established the goals and assignment of primary teams. Patients were surveyed for their knowledge of their primary teams as well as their ability to schedule and contact their primary providers. As a measure of the effects on clinical staff, a balancing survey was also conducted among providers impacted by the clinical assignment of teams. RESULTS: Our results demonstrate improvements across both coordination and communication as reported by patients. Additionally, the assignment of primary teams was met with high satisfaction and improvement in coordination and communication as reported by the clinical staff members of the HTC. CONCLUSIONS: Initiation of a quality improvement project and the creation of a primary team system were feasible at a large HTC and resulted in improvements in both patient-reported and staff-reported outcomes of coordination and communication of care.

Validation of Outcome Instruments for Pediatric Postthrombotic Syndrome: Introducing the Peds-VEINES-QOL, a New Health-Related Quality of Life Instrument.

BACKGROUND: There is need for validated outcome measures for postthrombotic syndrome (PTS) following pediatric venous thromboembolism (VTE), with a focus on quality of life (QoL). AIMS: This article assesses reliability and validity of two PTS and two QoL scales for children following lower extremity VTE. METHODS: Pediatric patients following lower extremity VTE were recruited from three thrombosis clinics. The Manco-Johnson (MJ) and the modified Villalta (MV) PTS scales were compared with each other and with the generic pediatric health-related QoL, PedsQL, and a newly developed pediatric venous-specific QoL, the Peds-VEINES-QOL. RESULTS: Eighty children following VTE and 60 healthy control children were enrolled. Internal consistency measured by Cronbach's α was high for the two QoL scales, and moderate for the two PTS scales. Inter-rater reliability using intraclass correlation coefficients was moderate to high for the MJ, MV, and Peds-VEINES-QOL, and moderate for the PedsQL. Evidence of high internal consistency by Cronbach's α coefficients, and moderate to high interitem correlations support the premise that a single construct was measured by each instrument. Correlations between the four instruments indicate convergent validity. CONCLUSION: The MJ and MV scales detect similar outcomes in children following VTE. As used, the MJ is slightly more sensitive to QoL because a positive diagnosis requires pain which is the leading factor in reduced QoL following deep vein thrombosis. When using the MV, a requirement for pain or abnormal use to diagnose PTS would make the MV a better predictor of QoL.

Antithrombin deficiency: A pediatric disorder.

INTRODUCTION: Hereditary antithrombin (AT) deficiency is an autosomal dominant thrombophilic disorder. Guidelines do not support routine testing of children based on personal or familial thrombosis. AIM: To investigate clinical, genetic and laboratory profiles of AT deficient children and their affected family members. MATERIALS AND METHODS: Data were analyzed from a prospective cohort of pediatric patients with AT deficiency. The SERPINC1 gene was sequenced for all individuals with available DNA. AT, thromboelastography (TEG), calibrated automated thrombogram (CAT), D-dimer, thrombin-antithrombin complex (TAT) and factor VIII activity were performed on patient samples. RESULTS: Thirty-six individuals from 11 families had AT deficiency (activities 45-70 U/dL) with incident thrombosis in 13 children and 10 adults (64% overall). Three neonates presented with middle cerebral artery and/or aortic occlusions with inferior vena cava and cerebral or renal vein thromboses in 2 of the 3. Two pre-pubertal children were symptomatic, one with cerebral venous sinus thrombosis who suffered recurrent arterial and venous thrombi. Both Type I and Type II AT deficiencies conferred a high severity of thromboses. Heterozygous SERPINC1 mutations were identified in seven families; three were novel, resulting in missense, splice site and frameshift alterations. Thrombin generation (CAT) was increased in all asymptomatic affected patients including 9 children and 1 adult. CONCLUSIONS: Genetic AT deficiency often presents in infants and children, warranting laboratory evaluation based on personal and family history. Increased thrombin generation was detected in all asymptomatic children and adults, suggesting a possible role in detecting and monitoring individuals at risk for thrombosis.

Current challenges for men and women with mild-to-moderate haemophilia.

Current treatments in the field of haemophilia are changing the phenotype of many patients with severe haemophilia to that of mild haemophilia. Despite this improvement, those with mild-to-moderate haemophilia A and haemophilia B continue to experience unmet needs. Whereas some patients with mild-to-moderate haemophilia experience similar complications to those of patients with severe haemophilia, they possess several unique attributes. These include a challenging diagnosis and variability in bleeding symptoms and treatment needs. In addition, haemophilia is an under-recognized condition in women even though many women with mild-to-moderate haemophilia experience the same symptoms and complications as men with haemophilia. These women also have their own unique challenges with this disease. This supplement highlights many of the unmet needs in men and women with mild-to-moderate haemophilia. The conclusions of each of these papers reinforce the need for additional research and resources for this patient population.

Outcome measures in Haemophilia: Beyond ABR (Annualized Bleeding Rate).

Options for management of haemophilia are increasing rapidly with completely novel therapeutic approaches that cannot be compared using traditional factor assays. In addition, as prophylaxis regimens have improved, bleeding rates have decreased, and consequently, it is difficult to show an impact of novel therapies on rates of spontaneous bleeding. There is currently an urgent need for a panel of outcome measures to compare therapies that are dissimilar in many essential ways. Conventional objective outcome measures including joint physical examination and joint imaging continue to hold a central importance. Factor assays are essential for evaluation of products derived from native factor genes, but are not applicable to some extended half-life factors or non-factor bypassing agents. Global assays including thrombin generation and chromogenic assays of factor X activation are under investigation for their usefulness in haemophilia assessment. Bleeding rate is a conventional subjective patient-reported outcome that, while decreasing in frequency, is indispensable as an outcome given that the primary manifestation of haemophilia is bleeding. Other patient-reported outcomes such as pain intensity and interference, health-related quality of life and activities and participation are increasingly important to distinguish superior outcomes in comparative trials. This review of outcome measures for haemophilia presents examples of existing outcome measures with an emphasis on their strengths and limitations.

Biomarkers of bone disease in persons with haemophilia.

INTRODUCTION: Persons with haemophilia (PwH) have abnormally low bone density and increased risk of fractures. We previously demonstrated decreased skeletal health in factor VIII (FVIII)-deficient mice. Thus, we hypothesized factor deficiency is an independent risk factor for decreased skeletal health. AIM: We seek to identify differences in bone-related cytokine expression among PwH and healthy controls. METHODS: We evaluated plasma samples from 79 participants with severe FVIII deficiency and 51 age-matched healthy controls. Plasma samples were assessed for RANKL and OPG, cytokines that regulate bone metabolism, and CTX-1, a biomarker for bone resorption, as well as 10 bone-related cytokines. RESULTS: CTX-1 is higher among samples from FVIII-deficient participants compared to controls (P < .01) but not among participants with recent factor use (within 24 hours of sample collection) (P = .21). Among PwH greater than 16 years of age (PwH ≥ 16), OPG is increased with recent factor use (P < .01) but not without (P = .34). Lower levels of TNF-α (P < .01), interleukin (IL)-12 (P < .01) and IL-10 (P < .001) were found among samples from PwH. Controlling for subject age, IL-12 and IL-10 levels are lower in PwH ≥ 16 (P < .01, P < .001) but not PwH under 16 (PwH < 16) (P > .05). Levels of TNF-α were lower among PwH < 16 only (P < .05). These differences are not observed in participants with recent factor use. CONCLUSIONS: In PwH, markers of bone metabolism and circulating cytokine levels are abnormal. Recent factor use reverses many of these differences suggesting FVIII replacement ameliorates this pathology. This study suggests bone disease present in PwH is intrinsic to FVIII deficiency.

Evaluating international Haemophilia Joint Health Score (HJHS) results combined with expert opinion: Options for a shorter HJHS.

INTRODUCTION: The Hemophilia Joint Health Score (HJHS) was developed to detect early changes in joint health in children and adolescents with haemophilia. The HJHS is considered by some to be too time consuming for clinical use and this may limit broad adoption. AIM: This study was a first step to develop a shorter and/or more convenient version of the HJHS for the measurement of joint function in children and young adults with haemophilia, by combining real-life data and expert opinion. METHODS: A cross-sectional multicenter secondary analysis on pooled data of published studies using the HJHS (0-124, optimum score 0) in persons with haemophilia A/B aged 4-30 was performed. Least informative items, scoring options and/or joints were identified. An expert group of 19 international multidisciplinary experts evaluated the results and voted on suggestions for adaptations in a structured meeting (consensus set at ≥ 80%). RESULTS: Original data on 499 persons with haemophilia from 7 studies were evaluated. Median age was 15.0 years [range 4.0-29.9], 83.2% had severe haemophilia and 61.5% received prophylaxis. Median (IQR) HJHS total was 6.0 (1.0-17.0). The items 'duration swelling' and 'crepitus' were identified as clinically less informative and appointed as candidates for reduction. CONCLUSION: Analysis of 499 children and young adults with haemophilia showed that the HJHS is able to discriminate between children and adults and different treatment regimens. Reduction of the items 'duration swelling' and 'crepitus' resulted in the HJHSshort , which had the same discriminative ability. Additional steps are needed to achieve a substantially shorter HJHS assessment.