Type 1 VWD classification revisited: novel insights from combined analysis of the LoVIC and WiN studies.

ABSTRACT: There is significant ongoing debate regarding type 1 von Willebrand disease (VWD) defintion. Previous guidelines recommended patients with von Willebrand factor (VWF) levels <30 IU/dL be diagnosed type 1 VWD, whereas patients with significant bleeding and VWF levels from 30 to 50 IU/dL be diagnosed with low VWF. To elucidate the relationship between type 1 VWD and low VWF in the context of age-induced increases in VWF levels, we combined data sets from 2 national cohort studies: 162 patients with low VWF from the Low VWF in Ireland Cohort (LoVIC) and 403 patients with type 1 VWD from the Willebrand in The Netherlands (WiN) studies. In 47% of type 1 VWD participants, VWF levels remained <30 IU/dL despite increasing age. Conversely, VWF levels increased to the low VWF range (30-50 IU/dL) in 30% and normalized (>50 IU/dL) in 23% of type 1 VWD cases. Crucially, absolute VWF antigen (VWF:Ag) levels and increase of VWF:Ag per year overlapped between low VWF and normalized type 1 VWD participants. Moreover, multiple regression analysis demonstrated that VWF:Ag levels in low VWF and normalized type 1 VWD patients would not have been different had they been diagnosed at the same age (ß = 0.00; 95% confidence interval, -0.03 to 0.04). Consistently, no difference was found in the prevalence of VWF sequence variants; factor VIII activity/VWF:Ag or VWF propeptide/VWF:Ag ratios; or desmopressin responses between low VWF and normalized type 1 VWD patients. In conclusion, our findings demonstrate that low VWF does not constitute a discrete clinical or pathological entity. Rather, it is part of an age-dependent type 1 VWD evolving phenotype. Collectively, these data have important implications for future VWD classification criteria.

Diagnosis and treatment of von Willebrand disease in 2024 and beyond.

MANUSCRIPT BACKGROUND AND AIM: The diagnosis and clinical care of patients with von Willebrand disease (VWD) has continued to evolve since the characterization of the von Willebrand factor (VWF) gene in 1985. This condition is almost certainly the most common inherited bleeding disorder, and the major symptomatic burden of the disease is experienced by females during their reproductive years. Diagnosis relies on the identification of a personal and family history of excessive mucocutaneous bleeding, and laboratory features consistent with quantitative and/or qualitative abnormalities of VWF. This review focuses on three aspects of VWD management, with current updates and a look into the future. MANUSCRIPT THEMES: First, we will address the role of genetics in the diagnosis and possible therapies for VWD. With current technologies, VWD genetic diagnosis is usually confined to the confirmation of type 2 subtypes of the disease and type 3 VWD analysis for family planning. While type 3 VWD is a potential candidate for the application of gene therapy, no treatments are currently close to entering the clinic. Second, the peri-procedural management of patients with VWD remains an important element of care. The choice of product, its dose and schedule all require careful consideration depending upon the type and disruptive nature of the planned procedure. Lastly, in addition to gene therapy, several other novel therapeutic interventions are also being developed for bleeding and prophylaxis in VWD. These include a VWF aptamer interfering with VWF clearance and bioengineered forms of VWF.

Impact of transcatheter aortic valve implantation on circulating von Willebrand factor in patients with severe aortic stenosis.

INTRODUCTION: Severe aortic stenosis (AS) can lead to degradation of high molecular weight (HMW) von Willebrand factor (VWF) which can result in haemostatic abnormalities. While studies have explored changes in VWF profiles before and after surgical aortic valve replacement (SAVR), the longer-term changes in VWF profiles pre- and post-transcatheter aortic valve implantation (TAVI) are less understood. AIM: Our primary objective was to identify differences in VWF multimer profiles and VWF function pre-TAVI and 1-month post-TAVI. Our secondary objective was to correlate VWF markers with measures of AS severity. METHODS: Adult patients with severe AS referred for TAVI at our institution were prospectively enrolled in this cohort study. Blood samples were collected for plasma analysis at three time points for all patients: 1 day pre-TAVI, 3 days post-TAVI, and 1-month post-TAVI. VWF antigen, activity, propeptide, collagen binding, multimers, and factor VIII coagulant activity were determined at each time point. Correlations between VWF parameters and severity of AS were assessed. RESULTS: Twenty participants (15 males, five females) with severe AS were recruited for the study. There was a significant increase in HMW VWF between pre-procedure and 1-month post-TAVI (p < .05). There was a transient increase in VWF antigen levels and activity at 3-days post TAVI that decreased to pre-TAVI levels at 1-month. There were no statistically significant correlations between VWF markers and AS severity. CONCLUSIONS: This is the first study to elucidate longer-term (>1 week) improvements in HMW VWF after a TAVI procedure in severe AS patients.

Von Willebrand Disease: Gaining a global perspective.

INTRODUCTION: Recent guidelines for von Willebrand Disease (VWD) highlighted the challenges in diagnosis and management. Identifying the number of persons with VWD (PwVWD) internationally will help target support to aid diagnosis of PwVWD. AIM: To examine international registration rates of PwVWD, the influence of income status, geographical region and the age and sex profile. Cumulatively, these data will be used to inform future strategy from the World Federation of Haemophilia (WFH) to address unmet clinical and research needs. METHODS: Data from the 2018/2019 WFH Annual Global Survey (AGS) were analysed, providing a global perspective on VWD registration. RESULTS: Registration rates are lowest in South Asia (0.6/million population) and highest in Europe/Central Asia (50.9/million population, 0.005%), but below the expected prevalence rate (0.1%). National economic status impacted VWD registration rates, reflecting variation in access to optimal healthcare infrastructure. Females represented the majority of PwVWD globally, however, in low-income countries (LIC) males predominated. Age profile varied, with markedly higher rates of paediatric registrations in North America, Middle East and North Africa and South Asia. Rates of type 3 VWD registrations were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings. CONCLUSION: Significant variation in registration rates of PwVWD exist internationally and is influenced by income status and the presence of HTC networks. Improved understanding of registration rates will enable targeting of advocacy to improve awareness, diagnosis and support for PwVWD internationally. KEY POINTS: Registration rates of People with Von Willebrand Disease (PwVWD) vary internationally and are influenced by national income status Although females represent the majority of PwVWD globally, in low income countries (LIC) males predominated, possibly related to stigma surrounding gynaecological bleeding. Rates of type 3 VWD registration were significantly influenced by economic status (81% of VWD diagnoses in LIC), suggesting only the most severe VWD types are diagnosed in resource limited settings.

Determining the incidence of postpartum haemorrhage among Ontario women with and without inherited bleeding disorders: A population-based cohort study.

INTRODUCTION: At a population level, there is a poor understanding of the incidence and pre-disposing risk factors of postpartum haemorrhage (PPH) among women with inherited bleeding disorders (IBD). AIM: To determine the incidence of PPH, and identify maternal factors associated with risk of PPH among women with IBD. METHODS: We conducted a retrospective cohort study using data housed within ICES (formerly known as the Institute for Clinical Evaluative Sciences). The cohort included women with an in-hospital, live or stillborn delivery, between January 2014 and December 2019. The primary outcome was PPH (identified by ICD-10 code O72). PPH incidence and risk factors were compared between women with and without IBD. Temporal trends were assessed using the Cochrane-Armitage test. Between group differences were assessed using standardised differences (std. difference). RESULTS: Total 601,773 women were included; 2002 (.33%) had an IBD diagnosis. PPH incidence was 1.5 times higher (7.3 vs. 4.9 cases/100 deliveries, std. difference .1) among women with IBD compared to women without. Women with IBD were slightly older (31.7 vs. 30.7 years), had higher rates of hypertension, previous PPH, and induction of labour. Women with IBD were more frequently diagnosed with anaemia (4.8% vs. 1.8%; std difference .17) and had lower haemoglobin levels at admission for delivery compared to women without IBD. CONCLUSIONS: This study contributes to the literature regarding obstetric bleeding among women with IBD, showing that anaemia at delivery may be an important risk factor for PPH. Given their predisposition to anaemia, clarifying this relationship will optimise management and outcomes.

Outcomes of long-term von Willebrand factor prophylaxis use in von Willebrand disease: A systematic literature review.

BACKGROUND: Von Willebrand Disease (VWD) is a common inherited bleeding disorder. Patients with VWD suffering from severe bleeding may benefit from the use of secondary long-term prophylaxis. AIM: Systematically summarize the evidence on the clinical outcomes of secondary long-term prophylaxis in patients with VWD and severe recurrent bleedings. METHODS: We searched Medline and EMBASE through October 2019 for relevant randomized clinical trials (RCTs) and comparative observational studies (OS) assessing the effects of secondary long-term prophylaxis in patients with VWD. We used Cochrane Risk of Bias (RoB) tool and the RoB for Non-Randomized Studies of interventions (ROBINS-I) tool to assess the quality of the included studies. We conducted random-effects meta-analyses and assessed the certainty of the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. RESULTS: We included 12 studies. Evidence from one placebo controlled RCT suggested that VWD prophylaxis as compared to no prophylaxis reduced the rate of bleeding episodes (Rate ratio [RR], .24; 95% confidence interval [CI], .17-.35; low certainty evidence), and of epistaxis (RR, .38; 95%CI, .21-.67; moderate certainty evidence), and may increase serious adverse events RR 2.73 (95%CI .12-59.57; low certainty). Evidence from four before-and-after studies in which researchers reported comparative data suggested that VWD prophylaxis reduced the rate of bleeding (RR .34; 95%CI, .25-.46; very low certainty evidence). CONCLUSION: VWD prophylaxis treatment seems to reduce the risk of spontaneous bleeding, epistaxis, and hospitalizations. More RCTs should be conducted to increase the certainty in these benefits.

Management of patients with elevated Self-BAT scores or other bleeding symptoms: Updated overview for primary care practitioners.

OBJECTIVE: To provide recommendations for management of patients presenting with elevated self-administered bleeding assessment tool (Self-BAT) scores or other bleeding symptoms in a primary care setting. SOURCES OF INFORMATION: Primary research sources, clinical review articles, and interviews with research staff, hematologists, and family physicians were used to create the poster tools and reference guide resources. MAIN MESSAGE: Recommendations to manage a patient with an elevated Self-BAT score or other bleeding symptoms include reviewing the results of the Self-BAT to clarify relevant symptoms, performing initial diagnostic laboratory tests, and doing basic symptom management. Clinical judgment should be used when determining whether referral to a hematologist is necessary, but referral should be considered if the bleeding score is abnormal or if initial management options are ineffective. Some bleeding symptoms warrant evaluation by a gastroenterologist, obstetrician-gynecologist, or otolaryngologist. CONCLUSION: Primary care providers should conduct a thorough review of the Self-BAT results and associated management recommendations when working with a patient presenting with an elevated score or other bleeding manifestations. A review consists of the clarification of relevant symptoms, appropriate initial laboratory workups, and patient education. Treatment options for symptom management should be explored while recognizing the threshold for referral to a hematologist.

Increased galactose expression and enhanced clearance in patients with low von Willebrand factor.

Glycan determinants on von Willebrand factor (VWF) play critical roles in regulating its susceptibility to proteolysis and clearance. Abnormal glycosylation has been shown to cause von Willebrand disease (VWD) in a number of different mouse models. However, because of the significant technical challenges associated with accurate assessment of VWF glycan composition, the importance of carbohydrates in human VWD pathogenesis remains largely unexplored. To address this, we developed a novel lectin-binding panel to enable human VWF glycan characterization. This methodology was then used to study glycan expression in a cohort of 110 patients with low VWF compared with O blood group-matched healthy controls. Interestingly, significant interindividual heterogeneity in VWF glycan expression was seen in the healthy control population. This variation included terminal sialylation and ABO(H) blood group expression on VWF. Importantly, we also observed evidence of aberrant glycosylation in a subgroup of patients with low VWF. In particular, terminal α(2-6)-linked sialylation was reduced in patients with low VWF, with a secondary increase in galactose (Gal) exposure. Furthermore, an inverse correlation between Gal exposure and estimated VWF half-life was observed in those patients with enhanced VWF clearance. Together, these findings support the hypothesis that loss of terminal sialylation contributes to the pathophysiology underpinning low VWF in at least a subgroup of patients by promoting enhanced clearance. In addition, alterations in VWF carbohydrate expression are likely to contribute to quantitative and qualitative variations in VWF levels in the normal population. This trial was registered at www.clinicaltrials.gov as #NCT03167320.

Evaluating the effectiveness of let's talk period's high school educational outreach program: A pilot study.

INTRODUCTION: Menorrhagia impacts ~40% of adolescent females, with about half having an underlying bleeding disorder, most commonly von Willebrand Disease (VWD). VWD affects ~1 in 1000 individuals, though many are unaware of their condition. Let's Talk Period (LTP) is an online knowledge translation platform aimed at increasing awareness of bleeding disorders symptoms, with a validated self-administered bleeding assessment tool (Self-BAT). AIM: To evaluate the effectiveness of the LTP high school outreach program in Grade 9 girls' health classes quantitatively, using baseline, post-presentation, and follow-up quiz scores, and qualitatively, with student and teacher feedback forms. METHODS: The 75-minute in-class presentations, developed in alignment with the 2015 Ontario Curriculum for Grade 9 Health and Physical Activity, were led by a haemophilia nurse, clinical research assistant, and undergraduate student from the LTP team. Students completed baseline, post-presentation, and 4-6-week follow-up Kahoot quizzes featuring the same nine questions to evaluate change in knowledge levels and retention. Both student and teacher feedback were collected. RESULTS: There was a significant increase (p < 0.001) from baseline to post-presentation scores, with a significant gain in knowledge, for all questions (p < 0.01). Students found content related to the basics and management of menstruation to be most interesting. Many had constructive feedback on how the presentation method could be improved. On average, the presentations were rated an 8.6 of 10 by students and 8.75 of 10 by teachers. CONCLUSION: The LTP high school outreach program effectively increases student knowledge of menorrhagia and bleeding disorders. It was well-received by students and staff alike.

Endothelial BMPR2 Loss Drives a Proliferative Response to BMP (Bone Morphogenetic Protein) 9 via Prolonged Canonical Signaling.

OBJECTIVE: Pulmonary arterial hypertension is a disease of proliferative vascular occlusion that is strongly linked to mutations in BMPR2-the gene encoding the BMPR-II (BMP [bone morphogenetic protein] type II receptor). The endothelial-selective BMPR-II ligand, BMP9, reverses disease in animal models of pulmonary arterial hypertension and suppresses the proliferation of healthy endothelial cells. However, the impact of BMPR2 loss on the antiproliferative actions of BMP9 has yet to be assessed. Approach and Results: BMP9 suppressed proliferation in blood outgrowth endothelial cells from healthy control subjects but increased proliferation in blood outgrowth endothelial cells from pulmonary arterial hypertension patients with BMPR2 mutations. This shift from growth suppression to enhanced proliferation was recapitulated in control human pulmonary artery endothelial cells following siRNA-mediated BMPR2 silencing, as well as in mouse pulmonary endothelial cells isolated from endothelial-conditional Bmpr2 knockout mice (Bmpr2EC-/-). BMP9-induced proliferation was not attributable to altered metabolic activity or elevated TGFß (transforming growth factor beta) signaling but was linked to the prolonged induction of the canonical BMP target ID1 in the context of BMPR2 loss. In vivo, daily BMP9 administration to neonatal mice impaired both retinal and lung vascular patterning in control mice (Bmpr2EC+/+) but had no measurable effect on mice bearing a heterozygous endothelial Bmpr2 deletion (Bmpr2EC+/-) and caused excessive angiogenesis in both vascular beds for Bmpr2EC-/- mice. CONCLUSIONS: BMPR2 loss reverses the endothelial response to BMP9, causing enhanced proliferation. This finding has potential implications for the proposed translation of BMP9 as a treatment for pulmonary arterial hypertension and suggests the need for focused patient selection in clinical trials.

An international survey to inform priorities for new guidelines on von Willebrand disease.

INTRODUCTION: von Willebrand disease (VWD) is an inherited bleeding disorder caused by a quantitative or qualitative dysfunction of von Willebrand factor. Clinicians, patients and other stakeholders have many questions about the diagnosis and management of the disease. AIM: To identify topics of highest importance to stakeholders that could be addressed by guidelines to be developed by the American Society of Hematology (ASH), the International Society on Thrombosis and Haemostasis (ISTH), the National Hemophilia Foundation (NHF) and the World Federation of Hemophilia (WFH). METHODS: A survey to determine and prioritize topics to be addressed in the collaborative development of guidelines for VWD was distributed to international stakeholders including patients, caregivers and healthcare providers (HCPs). Representatives of the four organizations coordinated the distribution strategy. The survey focused on both diagnosis and management of VWD, soliciting 7-point Likert-scale responses and open-ended comments, in English, French and Spanish. We conducted descriptive analysis with comparison of results by stakeholder type, gender and countries' income classification for the rating questions and qualitative conventional content data analysis for the open-ended responses. RESULTS: A total of 601 participants responded to the survey (49% patients/caregivers and 51% healthcare providers). The highest priority topics identified were diagnostic criteria/classification, bleeding assessment tools and treatment options for women and surgical patients. In contrast, screening for anaemia and differentiating plasma-derived therapy versus recombinant therapies received lower ratings. CONCLUSION: This survey highlighted areas of importance to a diverse representation of stakeholders in the diagnosis and management of VWD, providing a framework for future guideline development and implementation.

A Population-Based Cohort Study of Venous Thromboembolism Rates Following Surgery and During Adjuvant Chemotherapy in Patients With Colon Cancer.

BACKGROUND: There is an elevated risk of venous thromboembolism in patients treated for colon cancer. Postoperative venous thromboembolism has been studied previously, but no large study has compared the risks during different stages of treatment. OBJECTIVE: This study aimed to quantify and compare the risks of venous thromboembolism before surgery, after surgery, during adjuvant chemotherapy, and up to 365 days after surgery among patients with resected colon cancer. DESIGN: This is a population-based retrospective cohort study. SETTING: This study was conducted in a single-payer, universal health care setting (Ontario) between 2002 and 2008. PATIENTS: A total of 6806 patients with stage I to III colon cancer treated with surgical resection were included. INTERVENTIONS: Phases of treatment were evaluated, including preoperative, in-hospital, postoperative, during adjuvant chemotherapy, and 365 days postoperatively. MAIN OUTCOME MEASURES: Venous thromboembolism, as defined using diagnostic codes from administrative data sources, was the primary outcome measured. RESULTS: Of the 6806 patients included, 327 (5%) developed venous thromboembolism. Patients receiving adjuvant chemotherapy had a higher risk versus surgery-alone patients (6% vs 4%, p < 0.001). Of the 327 who developed venous thromboembolism, 32% (1.6% overall) were diagnosed during hospital admission and 13.5% (0.6% overall) were diagnosed between discharge and 30 days after surgery. The majority of venous thromboembolisms diagnosed in patients receiving adjuvant chemotherapy (53%, 3.1% of all patients receiving adjuvant chemotherapy) were diagnosed within 180 days of starting adjuvant chemotherapy. Venous thromboembolism was an independent risk factor for worse 5-year overall survival (HR, 1.65; 95% CI, 1.43-1.91; p < 0.001). LIMITATIONS: This study was limited by the potential for misclassification of venous thromboembolism and unknown compliance with prophylaxis recommendations. CONCLUSION: Patients who undergo treatment for stage I to III colon cancer are at considerable risk of developing venous thromboembolism. The risk is elevated in those who require adjuvant chemotherapy, and venous thromboembolism is associated with worse long-term outcomes. There may be a role of venous thromboembolism prophylaxis during all phases of treatment, including both after surgery and during adjuvant chemotherapy. See Video Abstract at http://links.lww.com/DCR/B123. UN ESTUDIO DE COHORTE POBLACIONAL DE LAS TASAS DE TROMBOEMBOLISMO VENOSO DESPUÉS DE CIRUGÍA Y DURANTE QUIMIOTERAPIA ADYUVANTE EN PACIENTES CON CÁNCER DE COLON: Existe un riesgo elevado de tromboembolismo venoso en pacientes tratados por cáncer de colon. El tromboembolismo venoso postoperatorio se ha estudiado previamente, pero ningún estudio grande ha comparado los riesgos durante las diferentes etapas del tratamiento.Cuantificar y comparar los riesgos de tromboembolismo venoso antes de la cirugía, después de la cirugía, durante quimioterapia adyuvante y hasta 365 días después de cirugía en pacientes con cáncer de colon resecado.Estudio retrospectivo de cohorte poblacional.Escenario de atención médica universal con pagador único (Ontario) entre 2002-2008.6,806 pacientes con cáncer de colon en estadio I-III tratados con resección quirúrgica.Fase de tratamiento, incluyendo preoperatorio, hospitalización, postoperatorio, durante quimioterapia adyuvante y 365 días después de la operación.Tromboembolismo venoso, tal como se define utilizando códigos de diagnóstico de fuentes de datos administrativos.Se incluyeron 6,806 pacientes, con 327 (5%) que desarrollaron tromboembolismo venoso. Los pacientes que recibieron quimioterapia adyuvante tuvieron un mayor riesgo en comparación con los pacientes con cirugía solamente (6% vs 4%, p <0.001). De los 327 que desarrollaron tromboembolismo venoso, 32% (1.6% en general) fueron diagnosticados durante el ingreso hospitalario y 13.5% (0.6% en general) fueron diagnosticados entre el alta y 30 días después de la cirugía. La mayoría de los tromboembolismos venosos diagnosticados en pacientes que recibieron quimioterapia adyuvante (53%, 3.1% de todos los pacientes con quimioterapia adyuvante) fueron diagnosticados dentro de los 180 días de comenzar la quimioterapia adyuvante. El tromboembolismo venoso fue un factor de riesgo independiente para una peor supervivencia general a 5 años (Hazard Ratio (cociente de riesgo) 1.65, IC 95% 1.43-1.91, p <0.001).Potencial de clasificación errónea del tromboembolismo venoso, cumplimiento desconocido de las recomendaciones de profilaxis.Los pacientes que se someten a tratamiento para el cáncer de colon en estadio I-III tienen un riesgo considerable de desarrollar tromboembolismo venoso. El riesgo es elevado en aquellos que requieren quimioterapia adyuvante y el tromboembolismo venoso se asocia con peores resultados a largo plazo. La profilaxis del tromboembolismo venoso puede desempeñar un papel durante todas las fases del tratamiento, incluyendo tanto el periodo posquirúrgico como durante la quimioterapia adyuvante. Consulte Video Resumen en http://links.lww.com/DCR/B123.

Novel insights into the clinical phenotype and pathophysiology underlying low VWF levels.

Critical clinical questions remain unanswered regarding diagnosis and management of patients with low von Willebrand factor (VWF) levels (30-50 IU/dL). To address these questions, the Low VWF Ireland Cohort (LoVIC) study investigated 126 patients registered with low VWF levels. Despite marginally reduced plasma VWF levels, International Society of Thrombosis and Haemostasis Bleeding Assessment Tool (ISTH BAT) confirmed significant bleeding phenotypes in the majority of LoVIC patients. Importantly, bleeding tendency did not correlate with plasma VWF levels within the 30 to 50 IU/dL range. Furthermore, bleeding phenotypes could not be explained by concurrent hemostatic defects. Plasma factor VIII to VWF antigen (VWF:Ag) ratios were significantly increased in LoVIC patients compared with controls (P < .0001). In contrast, VWF propeptide to VWF:Ag ratios >3 were observed in only 6% of the LoVIC cohort. Furthermore, platelet-VWF collagen binding activity levels were both significantly reduced compared with controls (P < .05). In response to 1-desamino-8-D-arginine vasopressin (DDAVP), peak VWF:Ag levels exceeded 100 IU/dL in 88% of patients and was sustained >100 IU/dL after 4 hours in 72% of subjects. In conclusion, our novel data suggest that low VWF levels can be associated with significant bleeding and are predominantly due to reductions in VWF synthesis and/or constitutive secretion. Although enhanced VWF clearance may contribute to the pathophysiology in some individuals, the absolute reduction in VWF plasma half-life is usually mild and not sufficient to significantly impact upon the duration of DDAVP-induced VWF response. This trial was registered at www.clinicaltrials.gov as #NCT03167320.

Pregnancy and delivery in women with von Willebrand disease.

Given the wide heterogeneity of phenotypes and of the underlying pathophysiological mechanisms associated with the disorder, pregnancy and delivery in von Willebrand disease (VWD) represent a significant clinical challenge. The variable pattern of changes observed during pregnancy of von Willebrand factor (VWF) and factor VIII (FVIII), the protein carried by VWF, prompts a careful evaluation of pregnant women with VWD to plan the most appropriate treatment at the time of parturition. However, there are also instances during pregnancy (amniocentesis, vaginal bleeding associated with placental detachment, sudden abortion) that may require urgent hemostatic treatment to prevent bleeding. Thus, women with VWD should start pregnancy after being well characterised as to their type, subtype and treatments. Women with VWD who have VWF and FVIII basal levels >30 U/dL typically normalise these levels at the end of pregnancy and specific anti-haemorrhagic prophylaxis is seldom required. On the contrary, those with basal levels <20 U/dL usually show a lesser increase and specific treatment is required. Some women with DNA variants associated with increased clearance can be treated with desmopressin, while those unresponsive or with contra-indications to this agent need replacement therapy. For these latter women, the risk of vaginal bleeding during pregnancy may be increased and prophylaxis with VWF concentrates required. Similarly, women with type 2 VWD who maintain reduced VWF activity throughout pregnancy require replacement therapy with FVIII/VWF concentrates. Delayed postpartum bleeding may occur when replacement therapy is not continued for some days. Tranexamic acid is useful at discharge to avoid excessive lochia.

Validation of the school age self-administered pediatric bleeding questionnaire (Self-PBQ) in children aged 8-12 years.

BACKGROUND: In the pediatric population, pathologic bleeding is often challenging to identify. The pediatric bleeding questionnaire (PBQ) was developed as a screening tool for von Willebrand disease (VWD) but was designed to be self-completed by children above 12 years of age. The study objective was to determine whether a modified Self-PBQ could be completed by 8- to 12-year-old children with adult assistance. PROCEDURE: The initial phase involved seven children who underwent cognitive debriefing to identify problems in the questionnaire, resulting in modifications to wording and response options. In phase 2, children completed the modified Self-PBQ independently or with assistance from their parent at five Canadian treatment centers. Parents filled out the Self-PBQ separately to serve as a comparison. Bleeding scores derived from the child self-report were compared to those of the parent proxy. RESULTS: Twenty-nine out of 31 patient/parent pairs successfully completed the Self-PBQ. Child and parent scores demonstrated a high level of agreement with an intraclass correlation (ICC) of 0.825. In the age subgroup analysis, the ICC was 0.834 and 0.824 for the 8- to 9-year-old and 10- to 12-year-old groups, respectively. The ICC was also determined in children with type 1 VWD (ICC = 0.829) versus those with more severe bleeding disorders (ICC = 0.802). Thus, age and disease severity had no significant effect on degree of agreement. CONCLUSIONS: Our study shows that agreement was maintained even in younger children aged 8-9 years and in children with varying bleeding phenotypes. This supports the administration of the modified Self-PBQ to 8- to 12-year-old children.

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.

Severity and Features of Epistaxis in Children with a Mucocutaneous Bleeding Disorder.

OBJECTIVE: To use standardized bleeding questionnaires to compare the severity and patterns of epistaxis in children with a mucocutaneous bleeding disorder and control children. STUDY DESIGN: The epistaxis sections of the Pediatric Bleeding Questionnaire (PBQ) administered to pediatric patients with von Willebrand disease or a platelet function disorder and healthy control children were reviewed. Scores and features of epistaxis (frequency, duration, onset, site, seasonal correlation, and need for medical/surgical intervention) were recorded. A PBQ epistaxis score ≥2 was defined as clinically significant. The Katsanis epistaxis scoring system was administered to eligible patients, ie, with ≥5 episodes of epistaxis per year. RESULTS: PBQ epistaxis scores were obtained for 66 patients, median age 12 years (range 0.6-18.3 years), and 56 control children. The median PBQ epistaxis score in patients was 2 vs 0 in control children (P <.0001). All of the features of epistaxis, except spontaneous onset, occurred in a significantly greater proportion of patients than control children with epistaxis. A total of 50% of the patients were graded as having severe epistaxis by the Katsanis epistaxis scoring system, and 30 of these (91%) had a clinically significant PBQ epistaxis score. CONCLUSION: Standardized bleeding questionnaires are useful in the assessment of epistaxis severity and pattern and may help to distinguish children with and without a mucocutaneous bleeding disorder.

Characterization of aberrant splicing of von Willebrand factor in von Willebrand disease: an underrecognized mechanism.

Approximately 10% of von Willebrand factor (VWF) gene mutations are thought to alter messenger RNA (mRNA) splicing through disruption of consensus splice sites. This mechanism is likely underrecognized and affected by mutations outside consensus splice sites. During VWF synthesis, splicing abnormalities lead to qualitative defects or quantitative deficiencies in VWF. This study investigated the pathologic mechanism acting in 3 von Willebrand disease (VWD) families with putative splicing mutations using patient-derived blood outgrowth endothelial cells (BOECs) and a heterologous human embryonic kidney (HEK 293(T)) cell model. The exonic mutation c.3538G>A causes 3 in-frame splicing variants (23del, 26del, and 23/26del) which cannot bind platelets, blood coagulation factor VIII, or collagen, causing VWD through dominant-negative intracellular retention of coexpressed wild-type (WT) VWF, and increased trafficking to lysosomes. Individuals heterozygous for the c.5842+1G>C mutation produce exon 33 skipping, exons 33-34 skipping, and WT VWF transcripts. Pathogenic intracellular retention of VWF lacking exons 33-34 causes their VWD. The branch site mutation c.6599-20A>T causes type 1 VWD through mRNA degradation of exon 38 skipping transcripts. Splicing ratios of aberrant transcripts and coexpressed WT were altered in the BOECs with exposure to shear stress. This study provides evidence of mutations outside consensus splice sites disrupting splicing and introduces the concept that VWF splicing is affected by shear stress on endothelial cells.

Clinical and laboratory variability in a cohort of patients diagnosed with type 1 VWD in the United States.

von Willebrand disease (VWD) is the most common inherited bleeding disorder, and type 1 VWD is the most common VWD variant. Despite its frequency, diagnosis of type 1 VWD remains the subject of debate. In order to study the spectrum of type 1 VWD in the United States, the Zimmerman Program enrolled 482 subjects with a previous diagnosis of type 1 VWD without stringent laboratory diagnostic criteria. von Willebrand factor (VWF) laboratory testing and full-length VWF gene sequencing was performed for all index cases and healthy control subjects in a central laboratory. Bleeding phenotype was characterized using the International Society on Thrombosis and Haemostasis bleeding assessment tool. At study entry, 64% of subjects had VWF antigen (VWF:Ag) or VWF ristocetin cofactor activity below the lower limit of normal, whereas 36% had normal VWF levels. VWF sequence variations were most frequent in subjects with VWF:Ag <30 IU/dL (82%), whereas subjects with type 1 VWD and VWF:Ag ≥30 IU/dL had an intermediate frequency of variants (44%). Subjects whose VWF testing was normal at study entry had a similar rate of sequence variations as the healthy controls (14%). All subjects with severe type 1 VWD and VWF:Ag ≤5 IU/dL had an abnormal bleeding score (BS), but otherwise BS did not correlate with VWF:Ag. Subjects with a historical diagnosis of type 1 VWD had similar rates of abnormal BS compared with subjects with low VWF levels at study entry. Type 1 VWD in the United States is highly variable, and bleeding symptoms are frequent in this population.