The prevalence of symptomatic von Willebrand disease in primary care practice

Screening for von Willebrand disease does not impact posttonsillectomy bleeding in a low-risk population

BACKGROUND

Bleeding is an important complication in children following tonsillectomy. Screening with coagulation tests prior to procedure is common to assess bleeding risk in the perioperative period, although ASH/ASPHO Choosing Wisely guidelines recommend against routine PT/PTT testing. Our aim was to compare von Willebrand factor antigen (VWF:Ag) and activity levels among patients with postoperative bleeding following tonsillectomy to evaluate for potential risk for bleeding.

PROCEDURE

Eligible subjects were aged 0-18 without significant personal or family history of major bleeding. Postoperative bleeding diaries were collected and symptoms measured using a postoperative bleeding score. Plasma VWF levels were drawn at time of anesthesia administration.

RESULTS

Postoperative bleeding occurred in 248 cases out of 1399 total subjects. Median VWF:Ag was 86 in patients with postoperative bleeding scores of 1-2, 86 for scores 3-4, 84 for scores 5-6, and 83 for scores >6, with no significant difference among groups (p = .98). Additionally, no difference was observed for subjects with multiple days of postoperative bleeding as compared to those with only 1 day of postoperative bleeding. Finally, no difference in VWF:Ag was observed for subjects whose first reported bleed occurred early in the postoperative course compared to those whose first reported bleed occurred later. VWF:Ag does not correlate with severity of bleeding, time of onset of first bleeding event, or recurrence of bleeding in healthy children with no personal or family history of bleeding who have postoperative bleeding following tonsillectomy.

CONCLUSIONS

This data does not support routine von Willebrand disease screening prior to tonsillectomy.

Bleeding patterns in patients before and after diagnosis of von Willebrand disease: Analysis of a US medical claims database

Introduction

Von Willebrand disease (VWD) is the most common inherited bleeding disorder. The bleeding phenotype is variable, and some individuals have persistent symptoms post‐diagnosis.

Aim

To characterize bleeding patterns in patients with VWD before and after diagnosis.

Methods

De‐identified claims data for commercially insured patients in the IQVIA PharMetrics® Plus US database (Jan‐2006 to Jun‐2015) were extracted. Eligible patients had ≥2 claims for VWD (ICD‐9 code 286.4), and continuous health‐plan enrolment for ≥2 years before and after diagnosis. Bleeding event, treatment and treating‐physician type were analysed for 18 months before and 7‐24 months after diagnosis, according to pre‐diagnosis bleeding phenotype (claims from one vs multiple bleed sites) and post‐diagnosis bleeding status (resolved [no post‐diagnosis bleed claims] vs continued [≥1 claim]).

Results

Data for 3756 eligible patients (72.6% female; 71.0% aged ≥18 years at diagnosis) were analysed. Overall, 642 (17.1%) and 805 (21.4%) patients had single‐ and multiple‐site bleed claims pre‐diagnosis, respectively, and 1263 (33.6%) patients (38.5% of women, 20.8% of men) continued to bleed post‐diagnosis. Multiple‐site bleeding was associated with pre‐diagnosis heavy menstrual bleeding (HMB), oral contraceptive (OC) use and nasal cauterization. Continued bleeding post‐diagnosis was associated with pre‐diagnosis gastrointestinal bleeding, HMB and epistaxis; pre‐diagnosis use of OCs, aminocaproic acid and nasal cauterization; and younger age at diagnosis. Few patients consulted a haematologist for bleed management.

Conclusion

Many patients with VWD have persistent bleeding from multiple sites and continue to bleed post‐diagnosis. Our findings suggest a need to optimize management to reduce the symptomatic burden of VWD following diagnosis.

A Comparative Evaluation of an Automated Functional Assay for Von Willebrand Factor Activity in Type 1 Von Willebrand Disease

Background

von Willebrand factor ristocetin cofactor activity (VWF:RCo) is the standard functional assay used for von Willebrand disease (VWD) diagnosis. However, it has some drawbacks including being time consuming and labor intensive and having high inter-laboratory variability. The HemosIL VWF activity assay has the advantages of both high speed and automation. The purpose of this study was to prospectively compare these two functional assays for type 1 VWD detection.

Methods

Plasma samples from 108 subjects were assessed in this study. HemosIL VWF activity was measured with the HemosIL latex immunoturbidimetric commercial kits by the ACL TOP coagulation analyzer. VWF:RCo was measured by platelet aggregation method. Pearson correlation analyses were performed to estimate the correlation of HemosIL VWF activity with VWF:RCo. Receiver-operator characteristic (ROC) curve analysis was used to evaluate the performance of the two diagnostic tests.

Results

The correlation coefficient between VWF:RCo and HemosIL VWF activity was 0.874 overall and was 0.761 and 0.811 in the cohorts of type 1 VWD and non-VWD, respectively. The sensitivity and specificity of HemosIL VWF activity assay for type 1 VWD identification were 94.7% and 80.0%, respectively, and the ROC curve of HemosIL VWF activity was larger than that of VWF:RCo (0.928 vs 0.863, p=0.0138). Finally, the positive and negative predictive values of the HemosIL VWF activity assay for type 1 VWD detection were 72.0% and 96.6%, respectively.

Conclusion

Our results demonstrate that the HemosIL VWF activity assay was an effective method for type 1 VWD screening and diagnosis. It carried good sensitivity and specificity and had a higher ROC curve than VWF:RCo besides showing good correlation with VWF:RCo. With its advantages of greater speed and automated performance, these results suggest that the HemosIL VWF activity assay was reliable and precise in the clinical setting.

Vascular abnormalities in patients with von Willebrand disease: A scoping review

BACKGROUND

Qualitative or quantitative defects of von Willebrand factor (VWF) such as in von Willebrand disease (VWD) are associated with vascular abnormalities, especially in the gastrointestinal (GI) tract. However, the locations, extent, and natural history of vascular abnormalities in patients with VWD is not well understood. To summarize the existing literature on the topic, we conducted a scoping review of vascular abnormalities in patients with VWD.

METHODS

We searched MEDLINE and EMBASE from inception to September 1, 2020, for studies clinically describing vascular abnormalities in VWD patients. Screening and data extraction was completed independently and in duplicate and each abnormality was documented individually.

RESULTS

After screening, 54 studies that reported patient level data comprising 146 patients were included. Type 2A (39%) and type 3 (14.4%) were the most common VWD subtypes. The most common site of vascular malformation was the GI tract, occurring in 124 patients (84.9%), whereas 18 (12.3%) had non-GI vascular abnormalities and 4 (2.7%) had both GI and non-GI vascular abnormalities. With respect to outcomes, the clinical course was not specified in the majority (55.5%) of patients. Survey and population level data were reported in nine studies, demonstrating vascular abnormalities occurred at higher rates in VWD and that VWD patients are overrepresented among those with those abnormalities.

CONCLUSION

Vascular malformations in patients with VWD occur primarily in the gastrointestinal tract. Type 2A and type 3 VWD are the most common subtypes affected. The clinical treatment and natural history of these abnormalities remains understudied and further research is needed.

Why is Misdiagnosis of von Willebrand Disease Still Prevalent and How Can We Overcome It? A Focus on Clinical Considerations and Recommendations

Despite von Willebrand disease (VWD) being the most common inherited bleeding disorder, its accurate diagnosis is frequently shrouded by diagnostic pitfalls. VWD is frequently under-diagnosed, over-diagnosed and misdiagnosed, leading to significant avoidable patient morbidity and health care system burden. At the heart of this dilemma lies the heterogeneity and complexity of von Willebrand factor (VWF) and associated defects, and the necessity of coalescing clinical and laboratory features to obtain an accurate diagnosis. Common pitfalls include poor clinical and scientific understanding and familiarity with VWD, incomplete clinical history and lack of routine use of standardised bleeding assessment tools (BAT), difficulty in accessing a comprehensive repertoire of laboratory tests, significant pre-analytical, analytical and post-analytical issues, and lack of expertise in laboratory testing and interpretation. Errors, resulting in under-diagnosis, over-diagnosis, and misdiagnosis of VWD, are presented and discussed. Strategies to minimise errors include better education of clinicians and laboratory staff on VWD, routine use of validated BAT, utilising a comprehensive gamut of laboratory investigations according to a standardised algorithm, and repeating testing to minimise pre-analytical errors. Recommendations on appropriate patient selection for VWD testing, how VWD should be investigated in the laboratory, and how to ensure test results are accurately interpreted in the correct clinical context are detailed.

Von Willebrand Disease: Current Status of Diagnosis and Management

Von Willebrand disease (VWD) is a common bleeding disorder, affecting male and female individuals equally, that often manifests in mucosal bleeding. VWD can be secondary to a quantitative (Type 1 and Type 3) or qualitative (Type 2) defects in Von Willebrand factor (VWF). Initial testing includes VWF antigen, as well as a platelet binding assay to differentiate between qualitative and quantitative defects. Further subtyping requires additional testing and is needed to ensure appropriate treatment. Desmopressin, antifibrinolytics, hormonal treatments for heavy menstrual bleeding, and VWF concentrates are commonly used in the treatment of VWD.

Spontaneous pyohaemothorax in a teenager with von Willebrand disease: a case report and review of literature

An 18-year-old man with a history of type 3 von Willebrand disease (VWD) presented with a spontaneous pyohaemothorax. Type 3 VWD may present with both mucocutaneous and deep-seated bleeds, such as visceral haemorrhages, intracranial bleeds and haemarthrosis. There have been very few cases described in children of spontaneous pyohaemothorax. Management of this patient was challenging due to risks of bleeding following surgical drainage, requiring constant replacement with von Willebrand factor concentrate, while monitoring factor VIII levels to balance the risks of thrombosis.

Economic Burden Associated with Major Surgery in Patients with von Willebrand Disease: A United States Retrospective Administrative Database Analysis

Purpose

To estimate the incremental economic burden of major surgeries in patients with von Willebrand disease (VWD).

Patients and Methods

This was a retrospective analysis of the IBM Health MarketScan^® database (2008–2018). Patients with at least two healthcare visits for VWD in the database who had undergone at least one major surgery unrelated to VWD (identified via International Classification of Diseases, Ninth and Tenth Revisions procedure codes) were included. Patients without VWD with major surgeries were selected from a 1% random database sample. All patients had ≥12 months of continuous healthcare plan enrollment before and following their first major surgery. Patients with VWD were matched (1:1) with patients without VWD using propensity score matching. Regression models compared healthcare resource utilization and costs between the matched cohorts over a 12-month period after patients’ index major surgery.

Results

After propensity score matching, 2972 pairs were selected. Musculoskeletal and digestive surgeries were the two most common major surgeries (patients with VWD, 39.6% and 25.0%; without VWD, 37.1% and 23.4%, respectively). Patients with VWD were significantly more likely (p<0.0001) to have an inpatient admission (odds ratio = 1.71; 95% confidence interval [CI] 1.52–1.92) or emergency room visit (odds ratio = 1.41; 95% CI 1.25–1.59) than patients without VWD. The numbers of inpatient admissions (incidence rate ratio [IRR] = 1.47; 95% CI 1.35–1.60), emergency room visits (IRR = 1.44; 95% CI 1.31–1.59), and outpatient visits (IRR = 1.16; 95% CI 1.11–1.21) per patient were also significantly greater for patients with VWD than for those without VWD (p<0.0001). Patients with VWD incurred significantly higher (p<0.0001) total healthcare costs (medical and pharmacy) per patient than patients without VWD ($50,733.89 versus $30,154.84, respectively).

Conclusion

Healthcare resource utilization and associated costs among patients undergoing major surgeries were significantly higher for those with VWD than for patients without VWD.

Ex vivo human placental transfer study on recombinant Von Willebrand factor (rVWF)

Deficiency or mutation of von Willebrand factor (VWF) leads to a coagulation disorder (von Willebrand disease; VWD) which requires a lifelong therapy. For avoiding maternal complications treatment may be necessary also in pregnancy, but placental transfer to the fetus might impact its coagulation system and evoke undesired side effects. As VWF is a very large molecule it may be assumed that it does not pass the placental barrier. To prove this hypothesis the materno-fetal transfer of recombinant VWF (rVWF) has been analyzed ex vivo in a total of 21 valid dual side placenta perfusions. Three groups of five placentas each have been perfused with physiological and up to ten-fold increased concentrations of rVWF for 2 h. Six placentas have been used for control perfusions. A series of different control parameters has been assessed for documentation of intactness and functionality of the placenta and the perfusion system. In not a single analysis, independent of time and concentration, rVWF was detected in the fetal circuit. In the maternal circuit VWF concentration decreased slightly during perfusion. These results demonstrate that recombinant VWF does not pass the human placenta.

Low VWF: insights into pathogenesis, diagnosis, and clinical management

von Willebrand disease (VWD) constitutes the most common inherited human bleeding disorder. Partial quantitative von Willebrand factor (VWF) deficiency is responsible for the majority of VWD cases. International guidelines recommend that patients with mild to moderate reductions in plasma VWF antigen (VWF:Ag) levels (typically in the range of 30-50 IU/dL) should be diagnosed with low VWF. Over the past decade, a series of large cohort studies have provided significant insights into the biological mechanisms involved in type 1 VWD (plasma VWF:Ag levels <30 IU/dL). In striking contrast, however, the pathogenesis underpinning low VWF has remained poorly understood. Consequently, low VWF patients continue to present significant clinical challenges with respect to genetic counseling, diagnosis, and management. For example, there is limited information regarding the relationship between plasma VWF:Ag levels and bleeding phenotype in subjects with low VWF. In addition, it is not clear whether patients with low VWF need treatment. For those patients with low VWF in whom treatment is deemed necessary, the optimal choice of therapy remains unknown. However, a number of recent studies have provided important novel insights into these clinical conundrums and the molecular mechanisms responsible for the reduced levels observed in low VWF patients. These emerging clinical and scientific findings are considered in this review, with particular focus on pathogenesis, diagnosis, and clinical management of low VWF.

ASH ISTH NHF WFH 2021 guidelines on the diagnosis of von Willebrand disease

BACKGROUND

von Willebrand disease (VWD) is the most common inherited bleeding disorder known in humans. Accurate and timely diagnosis presents numerous challenges.

OBJECTIVE

These evidence-based guidelines of 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) are intended to support patients, clinicians, and other health care professionals in their decisions about VWD diagnosis.

METHODS

ASH, ISTH, NHF, and WFH established a multidisciplinary guideline panel that included 4 patient representatives and was balanced to minimize potential bias from conflicts of interest. The Outcomes and Implementation Research Unit at the University of Kansas Medical Center (KUMC) supported the guideline-development process, including performing or updating systematic evidence reviews up to 8 January 2020. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subsequently subject to public comment.

RESULTS

The panel agreed on 11 recommendations.

CONCLUSIONS

Key recommendations of these guidelines include the role of bleeding-assessment tools in the assessment of patients suspected of VWD, diagnostic assays and laboratory cutoffs for type 1 and type 2 VWD, how to approach a type 1 VWD patient with normalized levels over time, and the role of genetic testing vs phenotypic assays for types 2B and 2N. Future critical research priorities are also identified.

Low VWF levels in children and lack of association with bleeding in children undergoing tonsillectomy

von Willebrand disease is a common bleeding disorder, but diagnosis can be difficult in young children who have not had bleeding challenges. We sought to evaluate the correlation between bleeding and von Willebrand factor (VWF) levels in children undergoing surgical challenge with tonsillectomy. Children ages 0 to 18 undergoing tonsillectomy without a personal or family history of bleeding were enrolled prospectively following informed consent and institutional review board approval. VWF levels were obtained at the time of surgery. VWF antigen (VWF:Ag) and VWF activity (VWF:GPIbM) were tested via enzyme-linked immunosorbent assay. Bleeding score was calculated using the International Society of Hematology bleeding assessment tool (BAT). Surgical and postoperative bleeding were determined using questionnaires filled out by the surgeon and patient/family. A total of 1399 subjects were enrolled with evaluable data, with a median age of 5 years. The median VWF:Ag was 85 IU/dL and the median VWF:GPIbM was 100 U/dL. Median BAT for the entire population was 0, including those with postoperative bleeding. There was no difference in VWF level between those who experienced postoperative bleeding and those who did not, with median VWF:Ag 85 vs 85 (P = .89) and mean VWF:GPIbM 98 vs 100 (P = .5). Interestingly, there was a difference in VWF levels with age, with median VWF:Ag 81 for those younger than 3 years, 82 for those 3 to 6 years, 90 for those 7 to 10 years, and 100 for those 11 to 18 years. A similar trend was noted for VWF:GPIbM. Of the 2 to 6 year olds, 5% had VWF:Ag <50, which would meet criteria for low VWF, but only 1.8% had an abnormal BAT at study entry and only 2.5% bled after surgery. Only 1 subject with low VWF had an elevated postoperative BAT >2. These data suggest that low VWF levels do not correlate with bleeding in children undergoing tonsillectomy. In addition, VWF levels outside the adult normal range in young children may be more common than previously thought and do not necessarily predict surgical bleeding.

Occurrence rates of von Willebrand disease among people receiving care in specialized treatment centres in the United States

INTRODUCTION

In the network of U.S. comprehensive haemophilia treatment centres (HTCs), von Willebrand disease (VWD) is the most common bleeding disorder other than haemophilia. Estimates of the size and characteristics of the VWD population receiving treatment are useful for healthcare planning.

AIM

Estimate the prevalence and incidence of VWD among males and females receiving care at U.S. HTCs (HTC-treated prevalence and incidence).

METHODS

During the period 2012-2019, de-identified surveillance data were collected on all VWD patients who visited an HTC including year of birth, sex, race, Hispanic ethnicity, VWD type, and laboratory findings and used to calculate period HTC-treated prevalence by VWD type and sex. Data from patients born 1995-1999 were used to estimate HTC-treated incidence rates.

RESULTS

During the period, 24,238 patients with a diagnosis of VWD attended HTCs; for 23,479 (96.9%), VWD type was reported or could be assigned. Age-adjusted HTC-treated prevalence was 8.6 cases/100,000 (7.2/100,000 for Type 1, 1.2/100,000 for Type 2 and 1.7/million for Type 3) and was twice as high in women as men (4.8 vs. 2.4 cases/100,000) for Type 1 and similar by sex for Type 2 and Type 3. HTC-treated Type 1 incidence increased over the period, averaging nearly threefold higher for women than men (26.2 vs. 9.9/100,000 live births). Sex differences were less for Type 2 (2.2 vs. 1.4 cases/100,000 births) and slight in Type 3.

CONCLUSION

Prevalence and incidence of HTC-treated VWD differ by sex and type and are likely strongly influenced by differences in rates of diagnosis.

Society of Family Planning clinical recommendations: Management of individuals with bleeding or thrombotic disorders undergoing abortion

Individuals who have bleeding disorders, thrombophilias, a history of venous thromboembolism (VTE), or who are taking anticoagulation medication for other reasons may present for abortion. Clinicians should be aware of risk factors and histories concerning for excessive bleeding and thrombotic disorders around the time of abortion. This document will focus on how to approach abortion planning in these individuals. For first-trimester abortion, procedural abortion (sometimes called surgical abortion) is generally preferred over medical management for individuals with bleeding disorders or who are on anticoagulation. First-trimester procedural abortion in an individual on anticoagulation can generally be done without interruption of anticoagulation. The decision to interrupt anticoagulation for a second-trimester procedure should be individualized. Individuals at high risk for VTE can be offered anticoagulation post-procedure. Individuals with bleeding disorders or who are anticoagulated can safely be offered progestin intrauterine devices. Future research is needed to better assess quantitative blood loss and complications rates with abortion in these populations.

Criteria for low von Willebrand factor diagnosis and risk score to predict future bleeding

BACKGROUND

Important diagnostic and clinical aspects of moderately reduced von Willebrand factor (VWF) levels are still unknown. There is no clear evidence which cutoff value (0.50 vs 0.60 IU/ml) should be used to diagnose "low VWF." Also, the incidence of bleeding after the diagnosis has been made, and risk factors for bleeding are unknown yet.

OBJECTIVES

To investigate the incidence of postsurgical bleeding, postpartum hemorrhage (PPH), and traumatic and spontaneous bleeding after low VWF diagnosis, and to develop a risk score to predict future bleeding.

METHODS

We performed a cohort study in patients with historically lowest VWF levels of 0.31 to 0.60 IU/ml. Clinical data of patients were retrospectively collected.

RESULTS

We included 439 patients with low VWF. During a follow-up of 6.3 ± 3.7 years, 259 surgical procedures, 81 deliveries, and 109 spontaneous and traumatic bleeding episodes were reported. The incidence of postsurgical bleeding was 2.7%, whereas 10% of deliveries was complicated by PPH. Overall, 65 patients (14.8%) had bleeding requiring treatment, which was not different between patients with historically lowest VWF levels of 0.31-0.50 and 0.51-0.60 IU/ml (p = .154). Age <18 years, abnormal bleeding score at diagnosis, and being referred for bleeding symptoms at the time of diagnosis were independent risk factors for bleeding during follow-up, and therefore included in the risk score.

CONCLUSIONS

The cutoff value of low VWF diagnosis should be set at 0.60 IU/ml. Furthermore, a risk score is developed to identify individuals with a high risk for bleeding after low VWF diagnosis.

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.

Incidence of von Willebrand disease in Denmark, 1995-2016: A cohort study

INTRODUCTION

Information about temporal development of von Willebrand disease (VWD) incidence at a population level is scarce. To our knowledge, no study has described the incidence of VWD at a population level.

AIM

To estimate overall and annual incidence rates of hospital diagnosed VWD in Denmark between 1995 and 2016 as well as the frequency of hospital treated bleeding episodes before and after VWD diagnosis.

METHODS

A registry-based cohort study that included all Danish patients with a first diagnosis of VWD in Denmark, identified in the Danish National Patient Registry through 1995-2016.

RESULTS

We identified 1,035 patients with a diagnosis of VWD. The overall incidence rate of VWD in 1995-2016 was 8.6 (95% CI: 8.1-9.2). The annual age-standardized incidence rate per 100 000 person-years varied between 4.1 (95% CI: 2.4-5.9) in 1998 and 16.7 (95% CI: 13.1-20.3) in 2005. A prominent peak in rates appeared from 2002 to 2008. One and five years before VWD diagnosis, 6% and 11.5% of the patients had at least one hospital treated bleeding episode. One and five years after diagnosis, the corresponding percentages were 7.9% and 13.4%.

CONCLUSION

These results are the first population-based estimates of VWD incidence. The incidence may be underestimated because asymptomatic individuals may not be diagnosed. The observed peak in incidence from 2002-2008 may be explained by increased medical attention, leading to more patients being diagnosed, rather than an actual increase in VWD incidence. However, overall, we observed no systematic changes in VWD incidence over the study period.

Successful Perioperative Management of Orthotopic Cardiac Transplantation in a Pediatric Patient With Concurrent Congenital von Willebrand Disease and Acquired von Willebrand Syndrome Using Recombinant von Willebrand Factor

Von Willebrand disease (VWD) is the most common bleeding disorder and reportedly affects 1:1,000 of the world's population. There are three subtypes of VWD characterized by a quantitative defect (types 1 and 3 VWD) or a qualitative defect (type 2 VWD). Type 1 VWD results in a partial deficiency of von Willebrand factor (VWF) and affects approximately 75% of individuals with VWD, whereas type 3 VWD results in a severe or complete deficiency of VWF. Individuals with type 2 VWD subtypes (types 2A, 2B, 2M, and 2N VWD) express a dysfunctional VWF protein that has impaired interactions with platelets or factor VIII. The majority of individuals with VWD have mild type 1 VWD and occasionally require bolus infusions of VWF for severe bleeding or major surgery. A subset of patients, especially those with type 2A or 3 VWD, may require more frequent VWF replacement or prophylaxis for refractory bleeding or bleeding prevention, respectively. Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder that primarily occurs as a result of an underlying disease or other pathologic mechanism. Cases of AVWS associated with heart valve defects, left ventricular assist devices, or congenital cardiac disease result from high shear stress in the circulation that induces VWF unfolding and subsequent proteolysis of high-molecular-weight multimers by ADAMTS-13. In rare instances, plasma-derived factor VIII-containing VWF concentrates have been administered to individuals with AVWS for persistent or challenging bleeding events. In this case report, the hemostatic challenges and the perioperative management of cardiac transplantation surgery using a novel recombinant VWF product in a pediatric patient diagnosed with AVWS concomitant with congenital type 1 VWD are described. Written informed consent was obtained from the patient's mother for this case report. The diagnosis of congenital VWD remains a challenge because of multiple potential modifiers that can alter VWF laboratory results. Concurrent conditions, such as congenital heart disease and the rare secondary condition of AVWS, in addition to congenital VWD, can further affect interpretation of coagulation studies. This can result in delays in diagnosis, increase severity of the bleeding phenotype, and complicate hemostatic management in individuals at risk for bleeding and thrombosis. A multidisciplinary approach, including anesthesiologists, cardiologists, cardiovascular surgeons, hematologists, and pharmacists, is critical to achieving optimal patient outcomes, as highlighted in this case report. As diagnostic capabilities and understanding of VWD broaden, future studies evaluating alternative treatment approaches for individuals with various types of VWD would be of great benefit to the medical community.

ASH ISTH NHF WFH 2021 guidelines on the management of von Willebrand disease

BACKGROUND

von Willebrand disease (VWD) is a common inherited bleeding disorder. Significant variability exists in management options offered to patients.

OBJECTIVE

These evidence-based guidelines from 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) are intended to support patients, clinicians, and health care professionals in their decisions about management of VWD.

METHODS

ASH, ISTH, NHF, and WFH formed a multidisciplinary guideline panel. Three patient representatives were included. The panel was balanced to minimize potential bias from conflicts of interest. The University of Kansas Outcomes and Implementation Research Unit and the McMaster Grading of Recommendations Assessment, Development and Evaluation (GRADE) Centre supported the guideline development process, including performing and updating systematic evidence reviews (through November 2019). The panel prioritized clinical questions and outcomes according to their importance to clinicians and patients. The panel used the GRADE approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 12 recommendations and outlined future research priorities.

CONCLUSIONS

These guidelines make key recommendations regarding prophylaxis for frequent recurrent bleeding, desmopressin trials to determine therapy, use of antiplatelet agents and anticoagulant therapy, target VWF and factor VIII activity levels for major surgery, strategies to reduce bleeding during minor surgery or invasive procedures, management options for heavy menstrual bleeding, management of VWD in the context of neuraxial anesthesia during labor and delivery, and management in the postpartum setting.

Translating the success of prophylaxis in haemophilia to von Willebrand disease

INTRODUCTION

There is limited awareness of von Willebrand disease (VWD), leading to challenges in both diagnosis and defining the optimal treatment approach for these patients. Patients with VWD are typically treated on-demand, with short-term prophylaxis used during surgery. In contrast, early initiation, and long-term use of prophylaxis is the standard of care in patients with severe haemophilia and can be successfully used to prevent joint bleeding and reduce chronic arthropathy.

AIM

To provide an understanding of the current evidence for the prophylactic treatment of patients with VWD and compare this to the management of patients with haemophilia.

METHODS

Review of published literature using a non-systematic search of PubMed and reference lists of sourced articles.

RESULTS

The successes seen with prophylaxis in haemophilia provide the rationale for long-term prophylaxis in patients with severe forms of VWD; preventing spontaneous, excessive and sometimes life-threatening bleeding, and reducing chronic joint disease. Currently, there are a few clinical trials assessing the long-term benefits of prophylaxis in VWD, and guidelines for the optimal prophylaxis treatment approach are lacking. Greater attempts to provide comprehensive, long-term care for patients with VWD are needed but still lacking within the community. This review highlights the success of prophylaxis in haemophilia and how this knowledge might be applied and translated to patients with VWD.

CONCLUSIONS

Lessons can be learned from the use of prophylaxis in haemophilia and prophylaxis should be considered the standard of care for a subgroup of patients with severe VWD.

Laboratory variability in the diagnosis of type 2 VWD variants

Essentials Patients with von Willebrand disease were enrolled in our study. Type 2 VWD diagnoses were based on original test results. Repeat evaluation resulted in many patients receiving a different type 2 diagnosis. Some genetic variants were particularly likely to move type 2 subcategories. ABSTRACT: Introduction Type 2 von Willebrand disease (VWD) refers to patients with a qualitative defect in von Willebrand factor. Accurate diagnosis of type 2 VWD subtypes can be challenging. Aim of the study To compare the historical diagnosis of type 2 VWD with current laboratory testing. Methods Subjects were enrolled in the Zimmerman Program either because of a preexisting diagnosis of VWD (retrospective cohort) or from evaluation for bleeding symptoms or suspected VWD (prospective cohort). Original diagnosis was assigned by the local center and central diagnosis was based on central laboratory testing. Results Two hundred and seventeen index cases in the retrospective cohort and 35 subjects in the prospective cohort carried a local diagnosis of type 2 VWD (29% and 6% of enrolled index cases, respectively). In the retrospective cohort, the diagnosis was confirmed in 66% of cases with a preexisting diagnosis of 2A, 77% 2B, 54% 2M, and 72% 2N. In the prospective cohort, 31% were confirmed 2A, 60% 2B, 23% 2M, and 100% 2N. Several genetic variants were repeatedly implicated in subjects with changed diagnosis: p.M1304R, p.R1315C, p.R1374C, and p.R1374H. Conclusions Both the prospective and retrospective cohorts demonstrated consistent variation in subjects whose diagnosis changed between 2A, 2B, and 2M. The importance of accurately diagnosing type 2 VWD may be most significant in the 2B subtype given potential concerns with the use of desmopressin in type 2B VWD. Some genetic variants appear in multiple types of VWD, making specific diagnoses challenging.

The potential role of emicizumab prophylaxis in severe von Willebrand disease

BACKGROUND

Severe von Willebrand disease (VWD) may be associated with chronic joint damage and may require prophylactic therapy. Emicizumab is a humanized bispecific antibody, which mimics the function of coagulation factor VIII (FVIII), and it has been approved for prophylaxis in hemophilia A.

METHODS

This is the first study assessing the potential future role of emicizumab as an alternative prophylactic treatment in patients with severe VWD, based upon a thrombin generation (TG) ex vivo analysis. We report 51 weeks of successful off label emicizumab prophylaxis in a child with severe VWD and recurrent hemarthroses and progressive arthropathy despite adherence to previous prophylaxis with replacement therapy.

RESULTS AND CONCLUSIONS

Our work demonstrated that ex vivo spiking with emicizumab increased TG in plasma from patients with type 3 VWD. Similar TG results were observed in our treated patient, whose therapy was well tolerated without any adverse events. Both in vitro and ex vivo TG data support sufficient hemostasis without exceeding the range seen in healthy volunteers. Further collaborative studies on the efficacy and safety of emicizumab prophylaxis in severe VWD is warranted.

Economic burden of major bleeding events in commercially insured patients with von Willebrand disease based on claims data from the United States

BACKGROUND: von Willebrand disease (VWD) can lead to serious, life-threatening bleeding events associated with substantial clinical and economic burden. OBJECTIVE: To estimate the prevalence, health care resource utilization (HCRU), and costs associated with major bleeding events in patients with VWD. METHODS: This was a retrospective analysis of the IBM MarketScan database (2008-2016). Selected patients had ≥ 2 VWD diagnoses, no diagnosis of acquired coagulation factor deficiency, and continuous health care plan enrollment for ≥ 12 months from eligibility start date. Prevalence was calculated as the proportion of eligible patients with ≥ 1 major bleeding event during the observation period (start to end of continuous eligibility). HCRU and costs in the 12-month continuous enrollment period following the first major bleeding event were compared with those from a comparable 12-month period for patients without major bleeding events. RESULTS: Of the 19,785 patients with VWD, 15% experienced ≥ 1 major bleeding event during a median follow-up of 4 years; 89% of these events were gastrointestinal bleeds. For the economic analysis, 773 patients with ≥ 1 major bleeding event and 4,285 patients without major bleeding events met the selection criteria. Controlling for baseline covariates, patients with major bleeding events had significantly (P < 0.0001) more inpatient admissions (incidence rate ratio [IRR] = 3.2; 95% CI = 2.78-3.77), longer inpatient stays (IRR = 3.9; 95% CI = 3.12-4.93), and more emergency department visits (IRR = 2.0; 95% CI = 1.77-2.27) and outpatient visits (IRR = 1.3; 95% CI = 1.19-1.34) than patients without major bleeding events. Annual health care costs were significantly higher (P < 0.01) for patients with major bleeding events than those without them (predicted mean cost differences: total = $20,890, pharmacy = $2,593, and medical = $18,293). CONCLUSIONS: Major bleeding events were associated with increased HCRU and costs, mostly inpatient costs. Therefore, optimizing therapy to prevent or reduce major bleeding events has the potential to reduce health care use and costs in patients with VWD. DISCLOSURES: This study was funded by Baxalta U.S. Inc., a Takeda company (Lexington, MA). The study sponsor was involved with the study design, analysis, and interpretation of data; writing of the manuscript; and the decision to publish the article. Lu, Wu, and Ewenstein are employees of Baxalta U.S. Inc., a Takeda company, and are Takeda stock owners. Farahbakhshian is an employee of Shire U.S. Inc., a Takeda company, and is a Takeda stock owner. Oladapo was an employee of Baxalta U.S. Inc., a Takeda company, at the time the analysis was completed and the manuscript developed, and is a Takeda stock owner.

Women and bleeding disorders: diagnostic challenges

Women with bleeding disorders suffer from multiple bleeding symptoms, including easy bruising, epistaxis, bleeding from minor wounds and the oral cavity, and bleeding after dental work or surgery. However, women with bleeding disorders especially suffer from gynecologic and obstetrical bleeding. These symptoms often are not recognized as abnormal, and many women are left undiagnosed and without access to appropriate medical care. Additional challenges to diagnosing women with bleeding disorders include lack of access to appropriate laboratory testing and issues around disease classification and nomenclature. Efforts have been undertaken to address these challenges, including the development and validation of bleeding assessment tools and strategies to clarify diagnostic thresholds and algorithms for von Willebrand disease (VWD) and platelet function disorders. Efforts to improve communication with the nomenclature used for hemophilia carriers are also underway.

Effectiveness and safety of hFVIII/VWF concentrate (Voncento®) in patients with inherited von Willebrand disease requiring surgical procedures: the OPALE multicentre observational study

BACKGROUND

In patients with moderate to severe qualitative and quantitative von Willebrand disease (VWD), even minor surgical procedures can be associated with a risk of life-threatening bleeding. Treatment strategies vary according to the levels of von Willebrand factor (VWF) and Factor VIII (FVIII). The aim of this study was to evaluate the effectiveness and the safety of Voncento^® (CSL Behring, Marburg, Germany), a plasma-derived FVIII/VWF concentrate (ratio 1:2.4), during surgeries performed in patients with inherited VWD.

MATERIALS AND METHODS

The OPALE study, a French multicentre observational study, was carried out from May 2016 to May 2019. It evaluated and analysed patients with inherited VWD (any type) requiring treatment with Voncento^® who underwent surgery.

RESULTS

In total, 92 patients were enrolled, and 66 patients underwent 100 surgical procedures: 69 minor and 31 major surgeries conducted in 30 patients with type 1, 50 patients with type 2, and 20 patients with type 3 VWD. During minor surgeries, the median number of infusions was one (range: 1-9), the pre-operative loading dose was 41 IU VWF:RCo kg^-1 (range: 18-147), and the total dose was 63 (range: 18-594). During major surgeries, the number of infusions was 4 (range: 1-23), the pre-operative loading dose was 43 (range: 25-66) IU VWF: RCo kg^-1, and the total dose was 155 (range: 40-575). The median FVIII:C levels ranged from 78 to 165 IU dL^-1 during 5 days after minor surgeries and from 86 and 167 IU dL^-1 during 11 days after major surgeries. VW:RCo levels ranged between 35 and 65 IU dL^-1 and between 34 and 76 IU dL^-1 after minor and major surgeries, respectively. The overall clinical effectiveness was qualified as "excellent" or "good" in 99% of patients. No thrombotic events related to Voncento^® were recorded.

DISCUSSION

The present study suggests that Voncento^® is an effective and well-tolerated therapy for the peri-operative management of patients with all VWD types.

How we diagnose 2M von Willebrand disease (VWD): Use of a strategic algorithmic approach to distinguish 2M VWD from other VWD types

INTRODUCTION

von Willebrand disease (VWD) is the most common inherited bleeding disorder and caused by an absence, deficiency or defect in von Willebrand factor (VWF). VWD is currently classified into six different types: 1, 2A, 2B, 2N, 2M, 3. Notably, 2M VWD is more often misdiagnosed as 2A or type 1 VWD than properly identified as 2M VWD.

AIM

To describe an algorithmic approach to better ensure appropriate identification of 2M VWD, and reduce its misdiagnosis, as supported by sequential laboratory testing.

METHODS

Comparative assessment of types 1, 2A, 2B and 2M VWD using various laboratory tests, including VWF antigen and several VWF activity assays, plus DDAVP challenge data, ristocetin-induced platelet agglutination (RIPA) data, multimer analysis and genetic testing.

RESULTS

Types 1, 2A, 2B and 2M VWD give characteristic test patterns that can provisionally classify patients into particular VWD types. Notably, type 1 VWD shows low levels of VWF, but VWF functional concordance (VWF activity/Ag ratios >0.6), with both baseline assessment and post-DDAVP. Types 2A, 2B and 2M VWD show VWF functional discordance (low VWF activity/Ag ratio(s)) dependent on the defect, but type 2M separates from 2A/2B VWD based on specific test patterns, especially with collagen binding vs glycoprotein Ib binding assays. RIPA identifies 2B VWD. Multimers separate 2M from 2A/2B.

CONCLUSION

We provide strategies to improve correct diagnosis of VWD, especially focussed on 2M VWD, and which can be used by most diagnostic haemostasis laboratories, reserving genetic analysis (if required) for confirmation.

Diagnosis of von Willebrand disease in Western Mexico

INTRODUCTION

Von Willebrand disease (VWD) is the most common inherited bleeding disorder with a prevalence of 0.1%, characterised by quantitative or functional deficiency of von Willebrand factor (VWF). VWD diagnosis is based on symptomology, biochemical and genetic tests, but limited laboratory resources and VWD heterogeneity still generate an important subdiagnosis gap worldwide and in our country.

AIM

To identify the type and subtype of VWD in a cohort of patients with a history of excessive bleeding in Western Mexico.

METHODS

This prospective cohort study from 2012 to 2019 included patients with mucocutaneous bleeding or abnormal laboratory tests. A standardised questionnaire and confirmatory tests were applied: FVIII:C, VWF activity, VWF antigen, and VWF multimeric analysis.

RESULTS

Of the 297 patients recruited, 207 (69.7%) were excluded because their values exceeded 50% in VWF activity and VWF antigen. Of those 90 remaining, 54 (18.2%) had low VWF, and only 36 patients (12.1%) were diagnosed with VWD. Among them, 17 (47.2%) had quantitative deficiencies, of whom 14 were assigned as type 1 and 3 as type 3.The remaining 19 cases were diagnosed as type 2 (52.8%): type 2A and 2B were the most frequent with 6 and 7 cases respectively; 4 cases were possible type 2M and two suggestive of 2N, however, this was not confirmed.

CONCLUSION

This study highlights the challenges of VWD diagnosis using a comprehensive panel of diagnostic tests which should extend to supplemental tests of VWF:CB, VWF:FVIIIB, and sequencing the VWD gene to confirm the results from the panel assays.

Desmopressin responsiveness by age in type 1 von Willebrand disease

BACKGROUND

Patients with type 1 von Willebrand disease (VWD) undergo a desmopressin (DDAVP) responsiveness challenge at diagnosis to assess whether DDAVP reverses their coagulation deficits. Current practice assumes DDAVP responsiveness remains constant over the lifetime. In patients with type 1 VWD, VWF-related parameters increase with age. This study explores whether DDAVP responsiveness also differs with age in this population.

METHODS

We conducted a retrospective chart review of 106 patients enrolled at our center since 1990. Our primary outcome was DDAVP responsiveness at 1 hour after DDAVP challenge. Locally weighted scatterplot smoothing fit and Spearman correlation coefficients were used to study the relationship between age and DDAVP responsiveness. For female participants, we used the Kruskal-Wallis test to compare absolute and relative changes in DDAVP responsiveness at various ages.

RESULTS

We had 79 patients (56 female) with type 1 VWD with at least 1 DDAVP challenge. In women with type 1 VWD, the absolute change in DDAVP responsiveness did not vary significantly with age (VWF:antigen [Ag], -0.08, P = .56; VWF:ristocetin cofactor [RCo], -0.16, P = .26; low-molecular-weight component of factor VIII [FVIII:C], -0.01, P = .93), nor did the relative change in DDAVP responsiveness (VWF:Ag, -0.03, P = .86; VWF:RCo, -0.25, P = .09; FVIII:C, -0.14, P = .34). The data plot suggested a relationship.

CONCLUSION

In women with type 1 VWD, DDAVP responsiveness may vary over the life cycle. Our exploratory findings are limited by our retrospective data, cross-sectional design, and small sample. Future studies should investigate the relationship between age and DDAVP responsiveness prospectively to evaluate whether there is clinical utility in rechallenging postpubertal female patients with type 1 VWD.

Navigating the Myriad of von Willebrand Factor Assays

von Willebrand factor (VWF) represents a large and complex adhesive plasma protein whose main function is to provide a bridge between blood platelets and damaged endothelium, and thus facilitate primary hemostasis. VWF also binds to FVIII, preventing early proteolysis, and delivers this cargo to sites of vascular injury, thereby promoting clot formation and secondary hemostasis. An absence, deficiency, or defect in VWF can lead to a bleeding diathesis called von Willebrand disease (VWD), considered the most common inherited bleeding disorder. Contemporary laboratory assays used in VWD diagnosis/exclusion comprise a myriad of assays that identify the quantity (level) of VWF, as well as the multitude of VWF activities. These may use the following test abbreviations: VWF:Ag, VWF:RCo, VWF:CB, VWF:GPIbR, VWF:GPIbM, VWF:FVIIB, VWF:Ab. The current review explains what these assays are, as well as their place in VWD diagnostics.

Coexistence of Von Willebrand disease and gastrointestinal stromal tumor (G.I.S.T): Case report of a rare and challenge association

Von Willebrand disease (VWD) is the most common inherited bleeding disorder and is caused by a quantitative (type 1 and 3) or qualitative (type 2) defect of Von Willebrand factor (VWF). Bleeding from the gastrointestinal (GI) tract is not uncommon in VWD and is usually associated with angiodysplasia. We report herein on the management of a patient affected by VWD2B with severe GI bleeding secondary to gastrointestinal stromal tumor (GIST) complicated by deep vein thrombosis (DVT). The current case demonstrated that the hemostatic balance, in RBDs under specific circumstances, can range from a tendency toward a hemorrhagic to normal or prothrombotic state. In these patients, a close collaboration between hematologists and surgeons can guarantee appropriate management in high-risk clinical scenarios.

New developments in von Willebrand disease

Von Willebrand disease (VWD) constitutes the most common inherited human bleeding disorder. It is associated with a mucocutaneous bleeding phenotype that can significantly impact upon quality of life. Despite its prevalence and associated morbidity, the diagnosis and subclassification of VWD continue to pose significant clinical challenges. This is in part attributable to the fact that plasma von Willebrand factor (VWF) levels vary over a wide range in the normal population, together with the multiple different physiological functions played by VWF in vivo. Over recent years, substantial progress has been achieved in elucidating the biological roles of VWF. Significant advances have also been made into defining the pathophysiological mechanisms underpinning both quantitative and qualitative VWD. In particular, several new laboratory assays have been developed that enable more precise assessment of specific aspects of VWF activity. In the present review, we discuss these recent developments in the field of VWD diagnosis, and consider how these advances can impact upon clinical diagnostic algorithms for use in routine clinical practice. In addition, we review some important recent advances pertaining to the various treatment options available for managing patients with VWD.

Electrophysiological Procedures in Patients With Coagulation Disorders - A Systemic Review

Catheter ablation (CA) is considered first-line treatment for many patients with symptomatic arrhythmias. Indications for CA are constantly increasing, as is the number of procedures. Although CA is nowadays regarded a safe procedure, there is a risk of complications, including both bleeding- and thrombosis-related events. Several factors contribute to periprocedural risk; of these, patient coagulation status is of considerable clinical relevance. In this context, even a simple procedure poses a considerable challenge in a patient with coagulation disorder. However, the level of evidence regarding CA in patients with coagulation disorders is very low. Neither experts' recommendations nor clinical guidelines have been presented so far. The aim of this article is to analyze potential procedure-related risks and provide clinicians with useful information and practical suggestions regarding optimization of procedural safety in patients with coagulation disorders.

Molecular and clinical profile of type 2 von Willebrand disease in Iran: a thirteen-year experience

Type 2 von Willebrand disease (VWD) is the most common congenital bleeding disorder, with variable bleeding tendency and a complex laboratory phenotype. In the current study, we report the clinical and molecular profile of a large number of Iranian patients with type 2 VWD. All exons, intron-exon boundaries, and untranslated regions were sequenced by Sanger sequencing for direct mutation detection. All identified mutations were confirmed in family members and by relevant bioinformatics studies. A total of 136 patients with type 2 VWD were diagnosed, including 42 (30.9%), 32 (23.6%), 38 (27.9%), and 24 (17.6%) patients with type 2A, type 2B, type 2M, and type 2N, respectively. Epistaxis (49%), gum bleeding (30.2%), ecchymosis (23.2%), and menorrhagia (16.3%) were the most common clinical presentations, while miscarriage (2.3%) and umbilical cord bleeding (0.8%) were the rarest. Thirty mutations were identified within the VWF gene, nine (30%) being novel, with p.Arg1379Cys (n = 20), p.Val1316Met (n = 13), p.Arg1597Trp (n = 13), p.Arg1374Cys (n = 10), p.Ser1506Leu (n = 10), and p.Arg1308Cys (n = 9) the most common. Type 2 VWD is a hemorrhagic disorder with variable bleeding tendency and a heterogeneous molecular basis in patients in Iran.

Comparative assessment of von Willebrand factor multimers vs activity for von Willebrand disease using modern contemporary methodologies

INTRODUCTION

Diagnosis of von Willebrand disease (VWD) is challenging due to heterogeneity of VWD and test limitations. Many von Willebrand factor (VWF) assays are utilized, including antigen (Ag), activity and multimer analysis. Activity assays include ristocetin cofactor using platelets (VWF:RCo) or other particles incorporating recombinant glycoprotein I ('VWF:GPIbR'), or other GPI binding assays using gain-of-function mutations ('VWF:GPIbM'), or collagen binding (VWF:CB).

AIM

To comparatively evaluate modern contemporary VWF activity assays vs VWF multimer analysis using modern contemporary methods.

MATERIALS AND METHODS

Several VWF activity assays (VWF:RCo, VWF:GPIbR, VWF:GPIbM, VWF:CB) assessed (typically as a ratio against VWF:Ag) against a new semi-automated procedure for different types of VWD (1, 3, 2A, 2B, 2M), plus control material (n = 580). The evaluation also focussed on relative loss of high and very high molecular weight multimers (HMWM and VHMWM) by densitometric scanning.

RESULTS

All evaluated VWF activity/Ag ratios showed high correlation to the presence/absence of HMWM and VHMWM, although VWF:CB/Ag and VWF:GPIbR/Ag ratios using an automated chemiluminescence method yielded highest correlation coefficients (r = .909 and .874, respectively, for HMWM). Use of the investigative procedure (VHMWM) identified fewer false positives for 'loss' in type 1 VWD.

CONCLUSIONS

This comparative investigation identified that new automated chemiluminescence VWF activity assays best identified relative loss or presence of HMWM and VHMWM according to activity to Ag ratios and an alternative investigative method for identifying VHMWM in multimer testing for a new commercial multimer method may lead to fewer false identifications of HMW loss in type 1 VWD.

Desmopressin acetate use in von Willebrand's disease: a survey on current practices in Brazil

Introduction

von Willebrand’s disease (VWD) is the most common inherited bleeding disorder. The 1-desamino-8-d-arginine vasopressin (DDAVP) is the treatment of choice for most responsive patients with VWD. The aim of this study was to evaluate DDAVP use in the management of VWD.

Method

We implemented a survey targeting medical doctors involved in the management of VWD in Brazil. Data was collected during a national congress on Hematology in November 2017.

Main results

A total of 51/80 (63.8%) questionnaires were collected. Most participants (76.2%) were hematologists who assisted adult patients and approximately 60% worked at hemophilia treatment centers (HTCs). Approximately half of participants who reported treating patients with VWD, assisted on average, less than 5 patients per month, and approximately 60% declared not having used any DDAVP for treating VWD in the previous year. However, most participants (70%) prescribed FVIII-containing VWF concentrate (VWF/FVIII) for 1–10 patients in the previous year. More than 80% of the participants recognized the main indications for DDAVP. Physicians who recognized indication for DDAVP for type 1 VWD more often had prescribed DDAVP in previous year (p =  0.03). Barriers for prescribing DDAVP varied and included unavailability of laboratory facilities and consumables for DDAVP testing and lack of skills on its prescription.

Conclusion

The DDAVP is currently underused in Brazil, as opposed to the excessive use of VWF/FVIII in VWD patients. We suggest the adoption of measures targeting educational and auditing programs. Furthermore, availability of laboratory reagents is needed to evaluate response and increment the correct use of DDAVP.

Utility of the platelet function analyser (PFA-100/200) for exclusion or detection of von Willebrand disease: A study 22 years in the making

INTRODUCTION

von Willebrand disease (VWD) is the most common inherited bleeding disorder and may alternatively arise as an acquired condition (AVWS). These represent deficiency and/or defects in von Willebrand factor (VWF). Closure times (CTs) obtained from the platelet function analyser (PFA) are highly sensitive to both VWD/AVWS. The current study has evaluated the utility of the PFA-100/-200 to exclude or detect laboratory identified VWD.

MATERIALS AND METHODS

An evaluation of the success or otherwise of prospective PFA testing to help exclude or detect VWD using data from a locally maintained database. This database contains patient information, results of PFA testing, results of VWF testing, platelet count and hematocrit, and additional information, for a current total of 3678 entries representing over 2 decades of testing.

RESULTS

According to selection criteria, a total of 142 samples were identified as derived from patients with VWD. All but one of these were also identified to have abnormal PFA CTs. Additional data sets of patients with 'low VWF' (n = 137), or borderline normal VWF (n = 163) were also identified, as well as patients with thrombocytopenia and/or low hematocrit (n = 487). In these cohorts, PFA CTs were often (but not always) abnormal. There was a strong association between VWF test parameter values and PFA CTs. Additional study samples comprised cases with normal VWF parameters but prolonged CTs (n = 594), as well as cases with normal VWF and normal CTs (n = 1292), permitting calculation of sensitivity of abnormal PFA for VWD (99.3%), as well as specificity (68.5%), negative predictive value (99.9%) and positive predictive value (19.2%), for a prevalence of 7.0%. Comparatively, normal PFA CTs were better able to exclude VWD than normal test results for individual VWF parameters.

CONCLUSION

This study reports on an evaluation of PFA CTs for identification or exclusion of VWD. In our dataset, representing over 22 years of experience, normal PFA CTs were able to predict absence of VWD with higher sensitivity than individual VWF test results.

Potential Undiagnosed VWD Or Other Mucocutaneous Bleeding Disorder Cases Estimated From Private Medical Insurance Claims

Introduction

Von Willebrand disease (VWD) is a common inherited bleeding disorder, but awareness among health care professionals is low. We estimated the number of cases of undiagnosed VWD or other mucocutaneous bleeding disorders among commercially insured patients in the United States with a recent history of bleeding events.

Methods

Patients with a VWD diagnosis who were users of or candidates for von Willebrand factor replacement were identified from the IMS PharMetrics Plus Database (2006–2015). We constructed a unary patient-finding model based on 12 prediagnosis variables that best defined this population, and applied this to undiagnosed patients with recent bleeding events from the same database. Cases of symptomatic undiagnosed VWD or other mucocutaneous bleeding disorders in the commercially insured population were estimated from the “best fit” (positive predictive value [PPV] 83%) and “good fit” (PPV 75%) patients thus identified.

Results

Overall, 507,668 undiagnosed patients with recent bleeding events were identified (86% female, 14% male). Application of the VWD model identified 3318 best-fit and 37,163 good-fit patients; 91% of best-fit patients were females aged <46 years, with heavy menstrual bleeding as the most common claim. Projection to the full commercially insured US population suggested that 35,000–387,000 patients may have symptomatic, undiagnosed VWD or other mucocutaneous bleeding disorders.

Discussion

Computer modeling suggests there may be a significant number of patients with symptomatic, undiagnosed VWD or other mucocutaneous bleeding disorder in the commercially insured population. Enhanced awareness of VWD symptoms and their impact, and of screening and testing procedures, may improve the diagnosis of VWD and reduce disease burden.

Physiological Roles of the von Willebrand Factor-Factor VIII Interaction

Von Willebrand factor (VWF) and coagulation factor VIII (FVIII) circulate as a complex in plasma and have a major role in the hemostatic system. VWF has a dual role in hemostasis. It promotes platelet adhesion by anchoring the platelets to the subendothelial matrix of damaged vessels and it protects FVIII from proteolytic degradation. Moreover, VWF is an acute phase protein that has multiple roles in vascular inflammation and is massively secreted from Weibel-Palade bodies upon endothelial cell activation. Activated FVIII on the other hand, together with coagulation factor IX forms the tenase complex, an essential feature of the propagation phase of coagulation on the surface of activated platelets. VWF deficiency, either quantitative or qualitative, results in von Willebrand disease (VWD), the most common bleeding disorder. The deficiency of FVIII is responsible for Hemophilia A, an X-linked bleeding disorder. Here, we provide an overview on the role of the VWF-FVIII interaction in vascular physiology.

Bleeding assessment tools to predict von Willebrand disease: Utility of individual bleeding symptoms

BACKGROUND

Bleeding assessment is part of the diagnostic workup of von Willebrand disease (VWD). Bleeding assessment tools (BATs) have standardized obtaining this information but have been criticized because they are time consuming.

OBJECTIVE

To use our legacy data to determine which questions from BATs are the strongest predictors of a VWD diagnosis.

PATIENTS/METHODS

Bleeding score data from 3 different BATs were used. Patients aged <12 years were excluded. Questions on BATs relate to different bleeding symptoms, and each symptom is scored by severity. Scores for each symptom were sorted based on whether they indicated clinically significant bleeding, and nonsignificant scores were set as the reference category. Multivariable logistic regression was used to determine the symptoms that were the strongest predictors of a laboratory-confirmed VWD diagnosis.

RESULTS

A total of 927 participants were included; 144 (16%) were patients with VWD, and 783 (84%) were healthy controls. The top 3 symptoms for which a clinically significant positive response increased the likelihood of VWD were hemarthrosis (odds ratio [OR], 19.2; 95% confidence interval [CI], 3.7-100.4), postsurgical bleeding (OR, 15.2; 95% CI, 5.9-38.9), and menorrhagia (OR, 10.3; 95% CI, 4.9-21.9). With each increase in number of bleeding symptom categories with clinically significant scores, subjects had a stepwise increase in odds of a VWD diagnosis.

CONCLUSIONS

Our results suggest that most of the bleeding symptoms on BATs are significant predictors of VWD, and there is value in assessing multiple bleeding symptoms when eliciting a bleeding history. Certain bleeding symptoms are more useful predictors than others. Future BAT revisions may consider adding a relative weighting to each symptom.

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.

The experience of postpartum bleeding in women with inherited bleeding disorders

INTRODUCTION

Postpartum hemorrhage (PPH) affects 6% of all deliveries and is the leading cause of maternal death worldwide (19.7%). The incidence of PPH in women with inherited bleeding disorders is substantially greater than in unaffected women; however, estimates of relative risk are highly variable. To date, their experience with postpartum bleeding has not been well studied.

OBJECTIVE

We set out to explore the experience with, understanding of, and attitudes regarding postpartum bleeding among women with inherited bleeding disorders.

METHODS

This qualitative study involved focused interviews of women with inherited bleeding disorders about postpartum bleeding. Women followed at a multidisciplinary clinic for women with inherited bleeding disorders who have experienced childbirth within the last 5 years were included in the study. The interview style was semistructured. Interviews continued until the point of saturation of themes. All interviews were transcribed and then analyzed using qualitative descriptive analysis.

RESULTS

We interviewed 10 women with inherited bleeding disorders. Themes that emerged were normalization of excessive vaginal bleeding, difficulty distinguishing normal from abnormal postpartum bleeding, and empowerment of women by having a clear delivery care plan.

CONCLUSION

In this study, women with inherited bleeding disorders were desensitized to heavy vaginal blood loss. As a result, excessive postpartum bleeding was not recognized by many of the women we interviewed. Results highlight the importance of a multidisciplinary delivery care plan for these women. Findings revealed key areas for targeted multidisciplinary intervention.

Semi-automated von Willebrand factor multimer assay for von Willebrand disease: Further validation, benefits and limitations

INTRODUCTION

Accurate diagnosis of von Willebrand disease (VWD) enables effective patient management. von Willebrand factor (VWF) multimer analysis provides useful information regarding VWF multimer structure, thereby aiding VWD subtyping and management; however, historically technically challenging assays have had limited utility. This study evaluates the Sebia Hydrasys Hydragel-11 semi-automated VWF multimer assay and further validates the Hydragel-5 gel system, as primarily pertaining to VWD diagnostics and monitoring of therapy.

METHODS

Provisionally diagnosed (via a reference assay test panel) archived patient samples and prospective test patient samples, including those undergoing desmopressin trial or therapy monitoring, along with commercial and in-house control material and various external quality assessment (EQA) samples, were analysed. VWF multimers were evaluated for presence, loss or partial loss of high molecular weight (HMWM) and intermediate molecular weight (IMWM) multimers by both visual inspection and densitometric scanning, and comparison with reference assay results.

RESULTS

All anticipated multimer patterns were reproduced, with patients generally showing multimer profiles matching expected patterns according to VWD type based on reference test panel 'diagnosis'. Occasional discrepancies were resolved by retesting. The increase in plasma VWF following desmopressin therapy was also clearly demonstrated. Multimer profiles of EQA samples complemented reference test panel results and matched EQA targets. There were some 'technical' limitations noted.

CONCLUSION

This easy to use, standardised, semi-automated multimer analysis system can demonstrate the multimer profile of VWD patients, thus representing an additional laboratory tool for improved diagnosis, thereby facilitating appropriate patient management.

The role of genetics in the pathogenesis and diagnosis of type 1 Von Willebrand disease

PURPOSE OF REVIEW

Von Willebrand disease (VWD) is a common bleeding disorder, but diagnosis of VWD is challenging, particularly with type 1 VWD. Although most clinicians use specific tests of von Willebrand factor (VWF) activity to classify patients with VWD, genetic testing for VWF defects is another potential method of diagnosis.

RECENT FINDINGS

Studies of patients with type 1 VWD report consistently that many, but not all, study participants have VWF gene defects. Certain populations, including those with VWF levels less than 30 IU/dl and those with clearance defects, are more likely to have a VWF sequence variant. In addition, a number of loci outside the VWF gene have been shown to affect VWF levels, including ABO, CLEC4M, STXBP5, and STAB2.

SUMMARY

Genetic defects in VWF are common, but not all defects lead to disease. Type 1 VWD in particular does not always have an associated VWF sequence variant. New data stemming from genome-wide association studies on modifier genes suggest that the etiology of type 1 VWD is multifactorial.