New advances in the diagnosis of von Willebrand disease

Improved prevention of bleeding episodes with emicizumab in 3 patients with concomitant hemophilia A and von Willebrand disease

The typical phenotype of hemophilia A (HA) is that of frequent bleeding episodes, up to several per month, unless prophylactic factor VIII (FVIII) replacement or alternatives are given. Related bleeding may be heightened in severity or frequency by co-morbid bleeding disorders. Based on the reported prevalence of von Willebrand disease (VWD) of up to 1% of the general population, the co-existence of HA and VWD occurs, but is likely less recognized. Prophylactic FVIII replacement may or may not adequately prevent bleeding in persons with HA and mild VWD, and plasma-derived concentrates containing FVIII and von Willebrand factor (VWF) may be used for more successful bleeding prophylaxis. However, therapy adherence remains problematic for many reasons, one being treatment via intravenous access. Emicizumab is a nonfactor subcutaneous prophylactic therapy for HA that may overcome this concern. We describe three patients, with severe HA and VWD, for whom regular FVIII/VWF prophylaxis was deemed inadequate. FVIII/VWF prophylaxis was replaced with weekly prophylactic injections of the bispecific monoclonal antibody, emicizumab. When the patients were transitioned to emicizumab, all experienced a significant reduction in their annualized bleed rate (ABR). Although the mechanism of action does not directly affect or replace VWF function, emicizumab may be an effective prophylaxis alternative to FVIII/VWF concentrate in patients with concomitant severe HA and VWD.

Von Willebrand Factor (VWF) multiplex activity assay differentiation of type 1 von Willebrand Disease (VWD) and variant VWD

INTRODUCTION

VWD diagnosis is challenging requiring multiple VWF activity tests using many individual assays. We have developed an ELISA-based VWF Multiplex Activity Assay (VWF-MAA) to address this concern; however, the ability of the VWF-MAA to discriminate between type 1 VWD, variant VWD, and normal subjects has not been evaluated.

AIM

To evaluate the VWF-MAA and its ability to differentiate between type 1 VWD, variant VWD and normal subjects in individuals undergoing an initial laboratory evaluation for bleeding.

METHODS

A total of 177 plasma samples from the Zimmerman Program: Comparative Effectiveness in the Diagnosis of VWD were evaluated from 11 centres across the US and Canada. The VWF-MAA was compared to Versiti Blood Research Institute (VBRI) and Local Center (LC) assigned VWD diagnosis.

RESULTS

Overall, 129/177 (72.9%) were correctly assigned as normal (non-VWD), type 1, or variant VWD compared to the VBRI assigned diagnosis. VWF-MAA assigned non-VWD accurately in 29/57 (50.9%) samples, and type 1 VWD accurately in 93/110 (84.6%) samples. Considering LC diagnosis where there was agreement with VWF-MAA and not VBRI diagnosis, type 1 VWD was accurate in 105/110 (95.5%) samples. Bland-Altman analysis demonstrated good correlation between laboratory methods. VWD, types 2A, 2B, 1C VWD were also assigned by the VWF-MAA.

CONCLUSIONS

We demonstrate that the VWF-MAA has utility in differentiating type 1 VWD, variant VWD and normal subjects in individuals undergoing an initial laboratory evaluation for bleeding.

Beyond the guidelines: how we approach challenging scenarios in the diagnosis and management of von Willebrand disease

Although von Willebrand disease (VWD) is the most common inherited bleeding disorder, its diagnosis and management are often challenging. Clinical practice guidelines, developed through systematic review of the medical literature and considering the best available evidence, provide guidance for common clinical scenarios. However, in the clinical setting, patients often present with characteristics and nuances that may fall outside the realm of available evidence and guidelines, and hence, shared decision-making will be essential in the evaluation and management of these patients. The challenges in the diagnosis of VWD are mainly attributable to the heterogeneity of the disorder, limitations of laboratory assays, and the significant impact of various physiologic processes on von Willebrand factor. The impact of physiologic normalization of von Willebrand factor, which may occur in various settings such as pregnancy, inflammation, or aging, remains uncertain, as is the optimal management in these scenarios. Multidisciplinary and individualized care, based on evolving evidence supported by clinicians, patients, caregivers, and stakeholders, will be needed to ensure the highest quality care for those who live with VWD.

Clinical and laboratory presentation of von Willebrand disease: Experience from a single center in KSA

Objectives

This study was aimed at assessing the clinical presentations and laboratory findings among patients diagnosed with vWD at a Saudi tertiary care unit.

Methods

This retrospective study included 189 patients with vWD who were followed up in our unit over 4 years. Clinical and laboratory data were collected and analyzed in SPSS.

Results

The median age of the study cohort was 30 years (range 11 months-56 years). The cohort had a female preponderance, with 32.30% males and 66.70% females. Bleeding from different sites was observed, mostly from the joints and muscles (23.90%), followed by the mucus membranes (14.60%), genitourinary areas (7.70%), ecchymoses (2.80%), and gastrointestinal areas (2.80%). A total of 48% of participants presented with more than one type of bleeding. A total of 105 (58.01%) participants had type 1; 29 (16.02%) had type 2; and 47 (25.96%) had type 3 vWD. Blood tests indicated the following mean value: hemoglobin, 116 ± 25.60 gm/L; ferritin, 75.80 ± 166.80 μg/L (median 28.5); vWAg, 0.40 ± 0.27IU/ml; and vWD:RCo, 0.32 ± 0.20IU/dL. The partial thromboplastin time was prolonged in 49.20% and normal in 50.80% of participants. Platelet function analysis values were prolonged in 92.90% and normal in 7.10% of participants. Comparative analysis of the O-type and non-O blood type showed that blood type O was significantly correlated with factor VIII (p-value = 0.013), vWF:RCo (p-value = 0.004), and vWF:Ag (p-value = 0.019).

Conclusion

Joint and muscle bleeds were the most common clinical presentations in our cohort. Although type 1 vWD was most prevalent in our cohort, we observed a comparatively higher prevalence of type 3, possibly because of ethnic differences or referral bias. We found a significant difference between O and non-O blood type regarding FVIII and vWF:Ag, and observed a more pronounced difference for vWD activity measuresd by vWF:RCo with blood type O being the systematic factor.

External Quality Assessment Data for Investigation of von Willebrand Disease: Focus on Relative Utility of Contemporary Functional von Willebrand Factor Assays. The United Kingdom National External Quality Assessment Scheme (UK NEQAS) Experience

Von Willebrand disease (VWD) is one of the most common hereditary bleeding disorders. Effective management of patients and their families depends on accurate diagnosis and subtype classification, and quality assurance including participation in proficiency testing programs is essential to ensure the accuracy of the panel of assays required to achieve this diagnosis. We report here findings from recent external quality assessment (EQA) exercises, as well as from a questionnaire about diagnostic practices employed by centers in the United Kingdom National Quality Assessment Scheme (UK NEQAS) performing von Willebrand factor (VWF) assays. Plasma samples from donors with VWD, "normal" donors, the International Society for Thrombosis and Haemostasis Scientific Subcommittee (ISTH SSC) plasma standard, and whole blood samples were sent to participants in the UK NEQAS BC program for VWF investigation. Calibration of lot#5 of the ISTH SSC plasma standard was shown to give improved comparability between the recovered value from an EQA exercise and the assigned potency for VWF activity assays. Diagnostic accuracy and precision amongst UK NEQAS participants was good, with an average 99% of centers reporting the correct interpretation for normal, type 1 and type 2 VWD samples, 100% diagnostic accuracy for centers performing FVIII binding assays, and good agreement amongst centers performing multimeric analysis. Genetic analysis of the VWF gene by specialist centers demonstrated errors in the genotyping process in one center, but also demonstrated failings in the interpretation of results in other centers. Despite evidence of good laboratory accuracy and precision in their assays, a questionnaire identified marked variation in diagnostic criteria employed, underlining the importance of guidelines to support the diagnosis of VWD.

Multiparameter platelet function analysis of bleeding patients with a prolonged platelet function analyser closure time

Patients referred for evaluation of bleeding symptoms occasionally have a prolonged platelet function analyser (PFA) closure time, without evidence for von Willebrand disease or impaired platelet aggregation. The aim of this study was to establish a shear‐dependent platelet function defect in these patients. Patients were included based on high bleeding score and prior PFA prolongation. Common tests of von Willebrand factor (VWF) and platelet function and exome sequencing were performed. Microfluidic analysis of shear‐dependent collagen‐induced whole‐blood thrombus formation was performed. In 14 PFA‐only patients, compared to healthy volunteers, microfluidic tests showed significantly lower platelet adhesion and thrombus formation parameters. This was accompanied by lower integrin activation, phosphatidylserine exposure and P‐selectin expression. Principal components analysis indicated VWF as primary explaining variable of PFA prolongation, whereas conventional platelet aggregation primarily explained the reduced thrombus parameters under shear. In five patients with severe microfluidic abnormalities, conventional platelet aggregation was in the lowest range of normal. No causal variants in Mendelian genes known to cause bleeding or platelet disorders were identified. Multiparameter assessment of whole‐blood thrombus formation under shear indicates single or combined effects of low–normal VWF and low–normal platelet aggregation in these patients, suggesting a shear‐dependent platelet function defect, not detected by static conventional haemostatic tests.

V-ATPase V0a1 promotes Weibel-Palade body biogenesis through the regulation of membrane fission

Membrane fission, the division of a membrane-bound structure into two discrete compartments, is essential for diverse cellular events, such as endocytosis and vesicle/granule biogenesis; however, the process remains unclear. The hemostatic protein von Willebrand factor is produced in vascular endothelial cells and packaged into specialized secretory granules, Weibel–Palade bodies (WPBs) at the trans-Golgi network (TGN). Here, we reported that V0a1, a V-ATPase component, is required for the membrane fission of WPBs. We identified two V0a isoforms in distinct populations of WPBs in cultured endothelial cells, V0a1 and V0a2, on mature and nascent WPBs, respectively. Although WPB buds were formed, WPBs could not separate from the TGN in the absence of V0a1. Screening using dominant–negative forms of known membrane fission regulators revealed protein kinase D (PKD) as an essential factor in biogenesis of WPBs. Further, we showed that the induction of wild-type PKDs in V0a1-depleted cells does not support the segregation of WPBs from the TGN; suggesting a primary role of V0a1 in the membrane fission of WPBs. The identification of V0a1 as a new membrane fission regulator should facilitate the understanding of molecular events that enable membrane fission.

Hemostatic profile detailing in apparent VWD cases: A cross sectional study

The von willebrand disease (vWD) accounts to be one of the most common hereditary bleeding ailment that amounts its incidence to almost 1.5% of normal population. It is mostly associated with a defect in primary hemostasis as well as secondary defect in coagulation factor VIII as diagnosis of vwd happened to be challenging with earlier diagnostic criteria's. Testing Vwd in menorrhagia patients was not at ease. A cross-sectional study was conducted in female patients who have visited obstetrics and gynecology clinic at King Saud University Medical City (KSUMC), Riyadh, Saudi Arabia. The inclusion criteria consist of adult female patients between 16 and 45 years old with menorrhagia. A sample of 45 patients were screened and selected for the above-mentioned study. The SPSS Statistical analysis package was performed to analyze the data's. The fisher's exact test was conducted to compare the demographic variables. The independent samples t-test was conducted to compare the means of subjects. The P value of ≤0.05 considered as statistically significant. The cases manifested with a history of bleeding during periods stretching from 7 to 90 days. The vWD was reported in 6.6 % (n = 3) women out of the total 45 patients. The vWF: Ac mean ± SD (51.4 ± 6.3) and vWF: Ag Mean ± SD (93 ± 67) were significantly lesser in vWD patients with that of non-vWD (98.7 ± 22.6) vs (116 ± 42.4) (p = 0.027) (p = 0.032) respectively. WBC, ESR, MCV, MCH, Hemoglobin, PLT count, INR, PT, APTT and FVIII showed no significant difference among the groups (p > 0.05).

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.

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.

Molecular classification of blood and bleeding disorder genes

The advances and development of sequencing techniques and data analysis resulted in a pool of informative genetic data, that can be analyzed for informing decision making in designing national screening, prevention programs, and molecular diagnostic tests. The accumulation of molecular data from different populations widen the scope of utilization of this information. Bleeding disorders are a heterogeneous group of clinically overlapping disorders. We analyzed the targeted sequencing data from ~1285 Saudi individuals in 17 blood and bleeding disorders genes, to determine the frequency of mutations and variants. We used a replication set of ~5000 local exomes to validate pathogenicity and determine allele frequencies. We identified a total of 821 variants, of these 98 were listed in HGMD as disease related variants and 140 were novel variants. The majority of variants were present in VWF, followed by F5, F8, and G6PD genes, while FGG, FGB, and HBA1 had the lowest number of variants. Our analysis generated a priority list of genes, mutations and novel variants. This data will have an impact on informing decisions for screening and prevention programs and in management of vulnerable patients admitted to emergency, surgery, or interventions with bleeding side effects.

Obstacles to Early Diagnosis and Treatment of Inherited von Willebrand Disease: Current Perspectives

Von Willebrand disease (VWD), the most common inherited bleeding disorder, is highly heterogeneous, and its early diagnosis may be difficult, especially for mild cases and in qualitative von Willebrand factor (VWF) defects. Appropriate VWD diagnosis requires the combination of personal and/or family history of bleeding and abnormal VWF laboratory testing. The use of bleeding assessment tools has been helpful in standardizing bleeding history collection and quantification of bleeding symptoms to select patients who may benefit of further hemostatic testing. Type 1 and 3 VWD which represent quantitative VWD variants are relatively easy to diagnose. The diagnosis of type 2 VWD requires multiple assessments to evaluate the effects induced by the responsible abnormality on the heterogeneous functions of VWF. Sensitive and reproducible tests are needed to evaluate different VWF activities, starting from measuring VWF-platelet interaction. In the recent years, several increasingly sensitive, rapid and automated assays have been developed, but they are not widely available so far. Genetic testing for VWD diagnosis is not a common practice because VWF gene is very large and highly polymorphic and therefore it is used only in specific cases. It is evident that the early and correct VWD diagnosis allows optimal management of bleeding and situations at risk. Tranexamic acid, desmopressin, replacement therapy with plasma-derived concentrates with a variable content of VWF and FVIII, or the new recombinant VWF are the different therapeutic options available. Careful VWD classification guides treatment because desmopressin is widely used in type 1 while replacement therapy is the cornerstone of treatment for type 2 and 3 variants.

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.

Laboratory misdiagnosis of von Willebrand disease in post-menarchal females: A multi-center study

Increased awareness of von Willebrand Disease (VWD) has led to more frequent diagnostic laboratory testing, which insurers often dictate be performed at a facility with off-site laboratory processing, instead of a coagulation facility with onsite processing. Off-site processing is more prone to preanalytical variables causing falsely low levels of von Willebrand Factor (VWF) due to the additional transport required. Our aim was to determine the percentage of discordance between off-site and onsite specimen processing for VWD in this multicenter, retrospective study. We enrolled females aged 12 to 50 years who had off-site specimen processing for VWF assays, and repeat testing performed at a consulting institution with onsite coagulation phlebotomy and processing. A total of 263 females from 17 institutions were included in the analysis. There were 251 subjects with both off-site and onsite VWF antigen (VWF:Ag) processing with 96 (38%) being low off-site and 56 (22%) low onsite; 223 subjects had VWF ristocetin co-factor (VWF:RCo), 122 (55%) were low off-site and 71 (32%) were low onsite. Similarly, 229 subjects had a Factor VIII (FVIII) assay, and 67 (29%) were low off-site with less than half, 29 (13%) confirmed low with onsite processing. Higher proportions of patients demonstrated low VWF:Ag, VWF:RCo, and/or FVIII with off-site processing compared to onsite (McNemar's test P-value <.0005, for all assays). These results emphasize the need to decrease delays from sample procurement to processing for VWF assays. The VWF assays should ideally be collected and processed at the same site under the guidance of a hematologist.