vWD Patients Research Articles

The severe von Willebrand Disease variant p.M771V leads to impaired anterograde trafficking of Von Willebrand factor in patient-derived and base-edited ECFCs

BackgroundVon Willebrand disease (VWD) is the most common inherited bleeding disorder caused by quantitative or qualitative defects of VWF. The p.M771V VWF variant leads to a severe bleeding phenotype in homozygous patients. However, the exact molecular mechanism remains unclear, which prevents personalized treatment of those VWD patients. ObjectiveThis study aims to characterize the underlying molecular mechanisms of the p.M771V variant in multiple representative ex-vivo cell models. MethodsECFCs were isolated from venous blood of VWD patients from the Willebrand in the Netherlands (WiN) cohort carrying homozygous and heterozygous p.M771V VWF variants. The p.M771V variant was also introduced in cord-blood derived ECFCs (CB-ECFCs) through adenine base editing and was overexpressed in HEK293 cells. Biosynthesis, storage, and secretion of VWF was studied using biochemical methods and confocal microscopy. ResultsTwo unrelated homozygous p.M771V patients presented with very low VWF activity and antigen levels in plasma. Patient ECFCs showed impaired proVWF processing into mature VWF with secreted VWF being severely reduced when compared to ECFCs of healthy donors. Multimer analysis of p.M771V ECFCs showed a deficiency of high molecular weight VWF multimers. Immunofluorescent staining revealed VWF retention in the endoplasmic reticulum (ER); this was confirmed in various populations of base edited CB-ECFCs harboring the p.M771V variant. ConclusionThe severe endothelial phenotype observed in patient-derived p.M771V ECFCs, HEK293 cells, and an original base-edited CB-ECFC modelling system, show that ER retention of VWF and failure to undergo subsequent proteolytic processing underpins the severe bleeding phenotype of patients with homozygous variants at M771.

LABORATORY DIAGNOSIS OF VON WILLEBRAND DISEASE

The aim of the study. To determine the frequency of Willebrand disease (VWD) in patients which turned to the SI IBPTM of the NAMS of Ukraine with hemorrhagic manifestations. Research metods. Object and research methods. The object of the study were 298 people with hemorrhagic syndrome aged from 7 months to 66 years old who have turned to the specialists of the institution since 01.01.2021, of which 198 (66,4%) came in for the first time. Coagulation hemostasis was investigated by methods that meet international standards and recommendations. Ristocetin-cofactor activity of factor Willebrand (VWF: RCo), content of the antigen VWF (VWF: AG), and coagulant activity of factor VIII (FVIII: C) were performed for the diagnosis of VWD. Results and Conclusions. VWD were found in 29 patients (9,7%) of the 298 people with hemorrhagic syndrome. VWD was revealed in 7,6% of patients from the 198 patients who were first investigate. The 15 (51,7%) VWD patients was diagnosed for the first time. In 48 (24,2%) was first diagnosed with hereditary or caused by various factors of disaggregational thrombocytopathy. Von Willebrand disease is the most common type of congenital hemostasis disorders (0,6-1,3% of the population), the type of inheritance is autosomal recessive/dominant. An algorithmic approach should be applied to diagnosis. Laboratory diagnosis consists of screening coagulological tests and three levels special tests. To establish the diagnosis, the necessary tests are determined by VWF: RCo, VWF: Ag and FVIII: C.

When Type 1 von Willebrand Disease Lives Together with Hashimoto Thyroiditis, Hypothyroidism, Hypoparathyroidism, Morbid Obesity, and Bariatric Surgery: A Case Report

Von Willebrand disease (vWD) is the most common bleeding disorder with type 1 being the more prevalent, although underdiagnosis is an actual concern. This case is the first clinical report of a type 1 vWD with several comorbidities submitted to bariatric surgery. The authors demonstrate the importance of a diagnosis and the consideration of other diseases or disturbances in vWD patients’ perioperative management. A multidisciplinary approach is crucial for minimizing and preventing bleeding risk.

Variant mapping using mass spectrometry–based proteotyping as a diagnostic tool in von Willebrand disease

Backgroundvon Willebrand disease (VWD) is the most common inherited bleeding disorder, characterized by either partial or complete von Willebrand factor (VWF) deficiency or by the occurrence of VWF proteoforms of altered functionality. The gene encoding VWF is highly polymorphic, giving rise to a variety of proteoforms with varying plasma concentrations and clinical significance. ObjectivesTo address this complexity, we translated genomic variation in VWF to corresponding VWF proteoforms circulating in blood. MethodsVWF was characterized in VWD patients (n = 64) participating in the Willebrand in the Netherlands study by conventional laboratory testing, DNA sequencing and complementary discovery, and targeted mass spectrometry–based plasma proteomic strategies. ResultsUnbiased plasma profiling combined with immune enrichment of VWF verified VWF and its binding partner factor VIII as key determinants of VWD and revealed a remarkable heterogeneity in VWF amino acid sequence coverage among patients. Subsequent VWF proteotyping enabled identification of both polymorphisms (eg, p.Thr789Ala, p.Gln852Arg, and p.Thr1381Ala), as well as pathogenic variants (n = 16) along with their corresponding canonical sequences. Targeted proteomics using stable isotope–labeled peptides confirmed unbiased proteotyping for 5 selected variants and suggested differential proteoform quantities in plasma. The variant-to-wild-type peptide ratio was determined in 6 type 2B patients heterozygous for p.Arg1306Trp, confirming the relatively low proteoform concentration of the pathogenic variant. The elevated VWF propeptide/VWF ratio indicated increased clearance of specific VWF proteoforms. ConclusionThis study highlights how VWF proteotyping from plasma could be the first step to bridge the gap between genotyping and functional testing in VWD.

Outcomes Following Total Hip Arthroplasty in Patients Who Have Von Willebrand Disease Depend on Postoperative Anticoagulation

BackgroundVon Willebrand disease (VWD) is the most common congenital bleeding disorder. This autosomal dominant condition arises from quantitative or qualitative defects of Von Willebrand factor. To our knowledge, this study leveraged a national database to characterize the largest VWD cohort of total hip arthroplasty (THA) patients to date, assessing 90-day postoperative adverse events and 5-year revision-free survival. MethodsAdult patients who underwent primary THA for osteoarthritis were identified from January 2010 to October 2021 in a nationwide database. Patients who had and did not have VWD were matched (4:1) on age, sex, and Elixhauser Comorbidity Index and compared with multivariable logistic regression. Patients were then categorized based upon venous thromboembolism (VTE) chemoprophylaxis prescription patterns to compare bleeding and thrombotic adverse events. ResultsOf 544,851 THA patients, VWD was identified in 309 patients (0.06%). The matched cohorts contained 1,221 patients who did not have VWD and 306 patients who have VWD. On multivariable analysis, VWD patients had increased odds of 90-day VTE (odds ratio [OR] = 1.86) and hematoma (OR = 3.40) (P < .05 for all). No difference in 5-year revision-free survival was found. The VWD patients receiving aspirin or no prescriptions had greater odds of VTE (OR = 2.39, P = .048). Those on other chemoprophylaxis agents had greater odds of hematoma (OR = 4.84, P = .006). ConclusionsPatients with VWD undergoing THA had increased odds of 90-day VTE if using aspirin or no prescriptions, or hematoma if using other chemoprophylaxis. There is a delicate balancing act of clotting versus bleeding that must be considered in managing such patients, but it was reassuring that no difference in overall 5-year revision-free survival was found.

A Compound Heterozygosis of Two Novel Mutations in vWF Exacerbates vWD in a Chinese Pedigree.

von Willebrand disease (vWD), caused by mutations in the von Willebrand factor (vWF) coding gene, is a disease characterized by abnormal coagulation activity and a severe tendency for hemorrhage. Therefore, identifying mutations in vWF is important for diagnosing congenital vWD. We studied a 23-year-old male vWD patient and his parents. Clotting methods were used to determine activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen (FIB) levels, FVIII activity. Chromogenic substrate method was used to determine vWF antigen and activity. The platelet count was determined. Mutations were searched using whole-exome sequencing and certified by Sanger sequencing. Clinical data, including activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), fibrinogen levels, FX activity, FX antigen levels, and the platelet count were collected. A mixing study was performed to eliminate the presence of coagulation factor inhibitors and lupus anticoagulants. Mutations were screened by using whole-exome sequencing (WES) and were verified by using Sanger sequencing. The proband showed severely decreased vWF antigen, vWF activity, and FVIII activity. RIPA (RISTO-CETIN-induced platelet aggregation) was 0%. Data from WES showed that the proband carried compound heterozygous variants vWF: NM_000552.5 (c.3213C>A p.Cys1071Ter) and vWF: NM_000552.5 (c.6598+2T>C). The proband's mother carried variant vWF: NM_000552.5 (c.3213C>A p.Cys1071Ter) while the proband's father carried variant vWF: NM_000552.5 (c.6598+2T>C). All laboratory test indexes of the proband's parents, including vWF antigen, vWF activity, and FVIII activity, were within the normal ranges. We identified a compound heterozygosis with two novel mutations in vWF (c.3213C>A, c.6598+2T >C) in a family pedigree, and our results demonstrate that the compound heterozygous mutations probably exacerbate vWD.

The use of a growth factor inhibitor in the treatment of recurrent bleeding in von Willebrand disease

Introduction. Von Willebrand disease (vWD) is a hereditary disorder of the blood coagulation system caused by a quantitative and/or qualitative defect of Willebrand factor (vWF), the pathogenetic principle of treatment of which is substitution therapy with combined concentrates of factor III and vWF. When bleeding foci of gastrointestinal angiodysplasia appear, hemostatic replacement therapy may not be effective.Aim: to present a clinical observation of the cessation of bleeding from gastrointestinal angiodysplasia after the use of a growth factor inhibitor in a vWD patient.Main fundings. A clinical case of treatment of a type III vWD patient with recurrent bleeding from foci of gastrointestinal dysplasia is presented. In order to stop bleeding, a course of therapy with a recombinant humanized monoclonal antibody targeting vascular endothelial growth factor (bevacizumab) was performed. 6 injections of the drug were administered, with a single dose being 400 mg. The interval between injections was 2 weeks. After bevacizumab therapy for 12 months, there were no cases of bleeding, although no hemostatic drugs were administered.

Perioperative hemostasis management in patients with von Willebrand disease: an institutional experience.

Patients with von Willebrand disease (vWD) undergoing surgery are routinely treated with von Willebrand factor (vWF)/factor VIII (FVIII) concentrate to control bleeding risk, but consensus is lacking on optimal dosing. This study aimed to evaluate the efficacy and safety of tailored doses of vWF/FVIII concentrate according to intervention-associated bleeding risk in vWD patients undergoing surgery. This was a retrospective analysis of vWD patients who underwent surgical procedures at a haemophilia centre. Patients received vWF/FVIII concentrate with dosage and duration of treatment dependent on intervention type (dental, gynaecological, abdominal or orthopaedic/traumatic) and bleeding risk (moderate/high). Eighty-three surgical procedures (42 patients) were included. Median preoperative loading doses of vWF/FVIII concentrate were 29.9 IU/kg and 35.7 IU/kg for interventions with moderate ( n = 16) or high ( n = 67) bleeding risk, respectively. The median perioperative dose was highest in orthopaedic or trauma-related surgery (140 IU/kg) and lowest in dental or gynaecological interventions (76.4 IU/kg and 80.0 IU/kg, respectively). During follow-up, no bleeding or other complications were observed in 95% of patients. Individually tailored doses of vWF/FVIII concentrate according to intervention-associated bleeding risk were effective in preventing postoperative bleeding, with few complications observed. These doses may be used as guidance in routine clinical care.

Age Regulates Desmopressin Responses in Patients with Low Von Willebrand Factor and Type 1 Von Willebrand Disease in the Lovic and Win Studies

Introduction Desmopressin is the treatment of choice in many patients with Low VWF and type 1 VWD. However, not all patients respond well to desmopressin. Moreover, desmopressin is contra-indicated in patients &amp;gt; 60 years in some countries. Interestingly however, previous studies have demonstrated that increases in plasma VWF levels seen with ageing are attributable to enhanced VWF biosynthesis coupled with reduced VWF clearance. Therefore, we investigated the hypothesis that Weibel-Palade body stores of VWF and clearance of VWF, and hence desmopressin responses, may vary with ageing. Methods We investigated datasets collected through the previously described Low VWF in Ireland Cohort (LoVIC) and Willebrand in the Netherlands (WiN) studies. All patients included in the LoVIC study had a personal bleeding history and VWF levels in the 30-50 IU/dL range. Conversely, WiN patients had either a personal bleeding history or positive family history, combined with VWF levels ≤ 30 IU/dL. Desmopressin was administered intravenously at a dosage of 0.3 μg/kg (maximum dose capped at 28 μg/kg) or intranasally at a total dosage of 300 μg. Complete desmopressin response was defined according to the 2021 ASH/ISTH/NHF/WFH guideline (i.e. increase of 2 times the baseline and sustained VWF and FVIII activity &amp;gt; 50 IU/dL for at least 4 hours). Results In total, 261 patients were included (178 WiN patients with type 1 VWD and 83 LoVIC patients with Low VWF). Based upon levels at inclusion in the WiN study versus original diagnosis, type 1 VWD patients were categorized into three groups - (i) 69 patients with persistent VWF levels &amp;lt; 30 IU/dL; (ii) 55 patients with partial correction in VWF levels into the 30-50 IU/dL range; and (iii) 54 patients with normalization of VWF levels &amp;gt; 50 IU/dL. Importantly, a complete response to desmopressin was observed in only 58% of WiN patients with persistent VWF levels &amp;lt; 30 IU/dL, whereas 100% of WiN patients with partially corrected or normalized levels and 100% of LoVIC patients had a complete response to desmopressin (p&amp;lt;0.001). Type 1 patients with persistent VWF levels &amp;lt; 30 IU/dL had significantly lower VWF:Ag at all time points after desmopressin compared to the other groups (Fig 1, p&amp;lt;0.001). Unexpectedly, VWF:Ag at 1, 4 and 24 hours after desmopressin was significantly higher in WiN normalized compared to LoVIC patients (Fig 1, p&amp;lt;0.001). Importantly however, the WiN normalized cohort was significantly older at the time of their desmopressin trial than the LoVIC group (41.9 ±13.8 years versus 32.9 ±10.7 years, p=0.002). Therefore, we hypothesized that the difference in VWF responses might be age-dependent. To investigate this concept, desmopressin responses for different age groups were assessed in LoVIC patients and WiN partially corrected and WiN normalized patients. Interestingly, an age-dependent effect on VWF responses at 1, 4 and 24 hours after desmopressin administration was observed (Fig 2). Older patients had both a significantly better initial desmopressin response at 1 hour after desmopressin (Fig 2, p=0.018), and a significantly prolonged half-life of VWF at 4 hours after desmopressin (Fig 2, p=0.004). Together, these data suggest that aging leads to both increased VWF synthesis/secretion and reduced clearance of VWF. Finally, we performed a retrospective cohort study to investigate whether desmopressin response could be utilized to predict which type 1 VWD patients would normalize their plasma VWF levels with aging. We included 94 LoVIC and 185 type 1 WiN patients with a mean follow-up of 9.7 ±3.9 years and 16.9 ±7.4 years respectively. We demonstrate that desmopressin response predicted the normalization of VWF levels with aging with a 100% accuracy (p&amp;lt;0.001). None of the patients with an incomplete response to desmopressin normalized during follow-up, whereas the median time of normalization was 13 years [7-26] in patients with complete response to desmopressin (p&amp;lt;0.001). Conclusion Cumulatively, we demonstrate that desmopressin responses increase significantly in VWD patients and Low VWF patients as they get older. Given our findings, future studies assessing the clinical efficacy and safety of using attenuated desmopressin doses in older patients should be considered. Alternatively, developing additional therapies that can be safely used to trigger secretion of enhanced Weibel-Palade body stores of VWF in older patients may provide novel treatment opportunities.

The Relationship between Low Von Willebrand Factor, Type 1 Von Willebrand Disease and Ageing - Novel Insights from the Lovic and Win Cohort Studies

Introduction For many years, there has been debate about how to optimally diagnose type 1 VWD. Initial guidelines proposed that only individuals with plasma VWF levels &amp;lt; 30 IU/dL should be diagnosed with ‘type 1 VWD’. This was revised in recent ASH/ISTH/WFH/NHF panel which recommended that patients with a significant bleeding history and plasma VWF of 30-50 IU/dL should also be diagnosed with type 1 VWD, as opposed to the discrete ‘Low VWF’ entity proposed in previous guidelines. In this study, we investigated whether Low VWF is a discrete clinical entity, or whether it is instead part of an age-dependent type 1 VWD evolving phenotype. Methods We utilized datasets from two renowned national cohort studies - the Low VWF in Ireland Cohort (LoVIC) and Willebrand in the Netherlands (WiN) studies. In the LoVIC study, patients had a personal bleeding history and historically lowest VWF levels in the 30-50 IU/dL range. In the WiN study, patients had either a personal bleeding history or positive family history, combined with historically lowest VWF levels ≤ 30 IU/dL. Based upon levels at study inclusion versus original diagnosis, WiN patients were categorized into three groups - (i) patients with persistent VWF levels &amp;lt;30 IU/dL; (ii) patients with partial correction in VWF levels into the range of 30-50 IU/dL; and (iii) patients with normalization of VWF levels &amp;gt; 50 IU/dL. The FVIII:C/VWF:Ag ratio was used to assess the synthesis/secretion of VWF and the VWFpp/VWF:Ag ratio was used to assess the clearance of VWF. Results In total, 565 patients were included (403 WiN patients with type 1 VWD and 162 LoVIC patients with Low VWF). Mean age at diagnosis was significantly increased in the LoVIC cohort compared to the three WiN subgroups (32.5 years versus 23.3 years, 26.5 years and 25 years respectively; p&amp;lt;0.001). Conversely, there was no difference in age at time of enrollment into both national studies (p=0.532). To assess the significance of age, we first investigated how plasma VWF:Ag varied over time in WiN type 1 VWD patients compared to the LoVIC cohort. Among the total WiN cohort (with initial VWF levels &amp;lt; 30 IU/dL), 47% of subjects (n=188) had VWF levels that remained &amp;lt; 30 IU/dL despite advancing age. Conversely, 30% of type 1 VWD patients (n=121) increased their plasma VWF levels into the Low VWF range (30-50 IU/dL) over time, whereas 23% (n=94) had age-dependent increments that led to complete normalization in VWF levels &amp;gt; 50 IU/dL. Similarly, 39% (n=63) of patients from the LoVIC study had normalization of VWF levels over time. Crucially, we observed that VWF:Ag in Low VWF patients clearly overlapped with those in normalized (&amp;gt; 50 IU/dL) type 1 VWD subjects, indicating that the LoVIC cohort is a subgroup within the WiN normalized subgroup (Figure 1). To further investigate this concept, we performed multiple regression analysis. Importantly, we observed that plasma VWF:Ag in the LoVIC cohort and the WiN normalized (&amp;gt; 50 IU/dL) subgroup would have not been different had they been diagnosed at the same age (difference of β=0.00 (95% CI -0.03 to 0.04)). Cumulatively, these results indicate that significant heterogeneity exists amongst type 1 VWD patients with respect to the effect of ageing on their plasma VWF levels. In addition, our findings demonstrate that because of age-dependent increases in plasma VWF:Ag, the majority of Low VWF patients would have been diagnosed with type 1 VWD had they undergone assessment earlier in life. Consistently, no difference in prevalence of VWF mutation (36.4% vs 22.6% respectively, p=1.000), FVIII:C/VWF:Ag ratio (1.24 ±0.24 vs 1.46 ±0.27 respectively, p=0.444) or VWFpp/VWF:Ag ratio (1.36 ±0.99 vs 1.75 ±0.38 respectively, p=1.000) was found between LoVIC and normalized WiN patients (Figure 2). Contrarily, WiN patients with persistent VWF levels &amp;lt;30 IU/dL had more often VWF gene variants (93.0%), higher FVIII:C/VWF:Ag ratio (2.65 ±1.62) and higher VWFpp/VWF:Ag ratio (6.14 ±7.05) compared to the other groups (Figure 2, p&amp;lt;0.001). Conclusion Our findings clearly demonstrate that Low VWF does not constitute a discrete clinical or pathological entity. Rather, it is part of an age-dependent type 1 VWD evolving phenotype, as demonstrated by the same VWF levels throughout life, genetic background and pathophysiology. This study has direct consequences for VWD diagnosis, the overall understanding of type 1 VWD as an evolving disease and for patients with low VWF/type 1 VWD.

Understanding the Disease Burden of Severe Von Willebrand Disease in a Resource Poor Country: An Indian Cohort Study

Background : The national economic status impacts identification of rare diseases which also reflects access to standard healthcare infrastructure.Though VWD is the commonest bleeding disorder, the disease remains under-recognized and underdiagnosed in India due to its phenotypic and clinical heterogeneity and the need for multiple and complex diagnostic tests. The hospital based data shows a contrasting prevalence to that of the west, in that type 3 is the commonest subtype followed by type 1 and type 2 subtype. The treatment patterns of VWD too differs between countries and geographical regions. Unlike hemophilia, the bleed patterns and treatment details are not very well defined. There is a need to identify the unmet needs in the area of diagnosis and management. Aim : The study is aimed to increase understanding of clinical manifestations, treatment practices along with Quality of life (qoL) in severe VWD patients from India Methods : This is a cross-sectional, patient reported retrospective analysis of severe VWD patients from India. The eligibility criteria is confirmed diagnosis of VWD with documented laboratory reports. An informed consent was taken from each patient before participation in the study and the study was initiated after obtaining approval from Institute Ethics Committee. The EQ-5D instrumentswere used to measure patient reported health related QoL. Results : A total of sixty two severe VWD patients were included in the present study. Mean age of the patients was 23.8 years (SD + 13.2 years); median 22 years (range 5-56 years) and the mean age of diagnosis was 4.9 years (SD + 6.9 years). The mean ABR was 12.6 (SD + 8.9). Twenty five patients (40%) had a positive family history and 37 (60%) of the patients reported parental consanguinity. Common bleeding symptoms were of mucocutaneous nature like epistaxis, ecchymoses and gingival bleed .Prolonged bleed from cuts was reported by 46 (74%) of patients and 14 out of 27 women (52%) in the reproductive age group complained of severe menorrhagia ( Table 1). In approximately 76% of the patients, the major treatment product was intermediate purity FVIII whereas 3 patients were still being treated with either cryprecipitate or fresh frozen plasma. The EQ-5D data reported a worse health state in the EQ-5D-5L dimensions of pain/discomfort (34% moderate and 8% moderate to severe problems),usual activities (21% moderate problems and 3% moderate to severe problems), self-care (21% moderate problems) and anxiety (moderate 21% and 2% moderate to severe).There were two deaths due to bleeding in the previous 10 years . Conclusion : In a resource limited country like India, type 3 is the predominant subtype presenting in the treatment centers. All patients had mucocutaneous bleeding with epistaxis being the predominant manifestation, but joint bleeding is also not uncommon. The study also reveals much lower than optimal QoL in all patients, mobility being the least affected parameter. Despite India being the pharmacy of the world, these conditions are neglected by stakeholders.

PB0704 Clinical Approach and Monitoring Treatment of Menorrhagia with PBAC (Pictorial Blood Loss Assessment Chart) in 20 VWD Patients

PB0704 Clinical Approach and Monitoring Treatment of Menorrhagia with PBAC (Pictorial Blood Loss Assessment Chart) in 20 VWD Patients

The Effects of Storage Time at 2–8 Degrees Celsius on the Stability of von Willebrand Factor in Thawed, Platelet-Poor Plasma

thawed samples with plasma stored at 2–8 °C for 24–96 hours. Materials and Methods: Plasma from healthy subjects with normal coagulation times and VWF panels was stored at -20 °C for one week. After thawing (at 0 hours), VWF:antigen (VWF:Ag), VWF:glycoprotein Ib binding assay (VWF:GPIbM), and VWF:collagen binding assay (VWF:CB) were assayed. The remaining plasma was stored at 2–8 °C and assayed at 24, 48, 72, and 96 hours. Differences between levels at baseline and 24, 48, 72, and 96 hours were deemed significant when P was &lt; 0.05. Results: Thirty-five samples were enrolled, with 25 from healthy subjects (VWF:Ag levels &gt; 0.50 kIU/L). Median levels (interquartile range) were as follows: VWF:Ag = 0.91 (0.72–1.06) kIU/L; VWF:GPIbM = 0.85 (0.69–1.04) kIU/L; and VWF:CB = 0.78 (0.62–0.97) kIU/L. VWF:Ag remained stable for 72 hours, while VWF:GPIbM decreased significantly after thawing. VWF:CB declined after 48 hours at 2–8 °C. Similar stability trends were observed in 10 additional samples from VWD patients (VWF:Ag = 0.42 (0.36–0.46) kIU/L). Conclusion: VWF:Ag and VWF:CB are stable in thawed plasma for 72 hours. VWF:GPIbM is less stable and should not be kept longer than 24 hours. Immediate testing of VWF:GPIbM after thawing is recommended.

Real-world healthcare costs and resource utilization in patients with von Willebrand disease and angiodysplasia

ABSTRACT Objective To describe the economic burden among VWD patients with angiodysplasia compared to VWD patients without angiodysplasia and the general population. Methods This was a retrospective analysis using the Merative MarketScan Commercial and Medicare Databases® (January 2011-September 2020). Selected patients had ≥1 medical claim for VWD or low VWF, ≥1 medical claim for AGD, and ≥3 GI-related bleeding episodes within a year. HCRU and all-cause costs were compared with the VWD (only) and the general cohorts. Results The mean total all-cause costs were $150,101 among patients with VWD and angiodysplasia (n = 34), higher compared to $48,249 among matched VWD patients without angiodysplasia (n = 136) and $31,029 among matched individuals of the general population [n = 136; p-value < 0.0001]. The differences in costs between groups were primarily due to inpatient care. During the 12-month follow-up, VWD patients with symptomatic (n = 35), asymptomatic (n = 81), and suspected (n = 378) angiodysplasia had an average of 4.1, 0.6, and 3.8 gastrointestinal (GI) bleeds, respectively. Desmopressin, VWF concentrates, and aminocaproic acid were the most frequent treatments used. The most frequent procedures to treat GI-related bleeding and underlying lesions were blood transfusion and laser therapy. Conclusions Despite recent therapeutic advances, there is room for considerable reduction of the disease burden in patients with VWD and angiodysplasia.

Commentary on Laffan et al expert consensus for equitable care for VWD.

In a recent issue of Haemophilia, Laffan et al. report ‘An expert consensus to define how higher standards of equitable care for von Willebrand disease can be achieved in the United Kingdom and Republic of Ireland.’’1 This project aimed to generate recommendations to improve equitable access to care for VWD patients. A modified Delphi approach was used and clear criteria for stopping and consensus were defined. Ultimately, eight recommendations were derived and include four that specifically address standardised and improved history taking about bleeding events, especially heavy menstrual bleeding, as well as additional recommendations focused on care delivery, better evidence for prophylaxis, and equity in terms of time to diagnosis and quality of life assessments. The expert authors are to be applauded for this effort and their focus on gender bias in the bleeding disorder community. A few points raised by this study merit additional discussion. The health care providers included were predominantly Haematologists, with Nurse Specialists as the second most common group; only one Obstetrician was included. Most respondents were from England and Ireland. Notably, a very high level of consensus was achieved after only one round of voting, which while reassuring, is not surprising given the relative homogeneity of the group. VWD patients interact with many parts of the health care system, and as a community, we need to turn our focus outward to other providers if we intend to truly improve the time to diagnosis and care. We also need to consider the specific challenges facing those living in low and middle-income countries, as the solutions must be tailored to the available resources and cultural settings. Certainly, the foundation of change needs to involve rejecting sexist attitudes towards individuals with bleeding disorders and valuing the lived experiences of patients. Along those lines, the patient voice must be included in future efforts directed at improving equitable access to care. We need to listen to patients and patient organizations to understand their priorities and tailor our approaches appropriately. Failure to do so could perpetuate the current state of inequity, no matter how well-meaning the intentions. As an example, the ongoing focus of many national and international organizations on hemophilia (as evidenced by the very names of these organisations) creates a barrier for VWD patients and healthcare providers. Women have been telling us for years that they feel poorly represented within Hemophilia Treatment Centres and by Hemophilia-focused patient organisations.2-4 It is time we listen and act. Of note, the recommendation with the lowest consensus at 80% was ‘Patients should always be involved in treatment options for their VWD’—clearly, there is work left to do to truly achieve patient-centred care. The authors include a detailed discussion of the barriers to care, which are many, especially at the primary care level. Engaging with primary care practitioners (PCP), who are often the first point of contact for someone with bleeding symptoms, seems an additional critical step in creating a functional and integrated system to diagnose and manage these patients. The value of multi-disciplinary clinics has been recognised, but in contrast to these being specialist centred, the inclusion of PCP in these models of care could be considered. Lastly, as highlighted by the authors, the quality of evidence for critical aspects of the care of VWD patients, such as prophylaxis, is poor. Although there are many barriers to performing these studies including the multiple types and subtypes of VWD as well as the numerous bleeding symptoms experienced by patients, the need for high-quality evidence is clear. In the recently published ASH (American Society of Hematology) ISTH (International Society on Thrombosis and Hemostasis) NHF (National Hemophilia Foundation) WFH (World Federation of Hemophilia) VWD Management Guidelines, all 12 recommendations were conditional, due to the lack of high-quality evidence.5 Laffan et al. appropriately identify the need for future studies to further develop the evidence base on which we base management decisions for VWD patients. Paula James receives research funding from Bayer and consultancy fees from Band/Guardian Therapeutics and Star/Vega Therapeutics. Data sharing not applicable to this article as no datasets were generated or analysed during the current study.

The relative risk of ischemic cerebrovascular accident in patients with Von Willebrand disease.

Cerebrovascular accident (CVA) is one of the leading causes of death in the United States. Von Willebrand factor plays an important role in platelet activation and adhesion. It remains unclear whether Von Willebrand disease (vWD) is associated with a decreased risk of developing CVA. The study aimed to compare the relative risk (RR) of CVA in patients with and without vWD. We queried the National Inpatient Sample from 2009 to 2014 for discharge data and records for vWD and CVA using International Classification of Diseases, Ninth-Revision codes. The unadjusted and adjusted RR of CVA in patients with and without vWD were estimated using log-binomial model. Descriptive measures including means, medians, standard deviations, and range were presented based on normality test of continuous data. The prevalence of CVA was lower in patients with vWD than in those without vWD (1.31% vs 2.04%), with a RR of 0.64 (95% confidence interval (CI): 0.60-0.68). After adjusting for common CVA risk factors, the RR remained lower in vWD patients: 0.81 (95% CI: 0.76-0.86). vWD is associated with a lower RR of developing CVA. This suggests that deficiency of Von Willebrand factor is potentially protective against the development of CVA. To the best of our knowledge, this is the first study in humans to compare the RR of CVA in patients with and without vWD. Future studies are needed to explore causal relationships and therapeutic benefits.

Characterization of CNVs in a Large Cohort of VWD Patients Reveals Relationship between Disrupted Regions, Clinical Variables and Disease Type

BACKGROUND: Copy-number variants (CNVs) have been associated to all VWD types. Although many of the underlying pathological mechanisms have not been investigated, in-frame deletions have been shown to cause defects in VWF biosynthesis and secretion. While there are previous studies describing CNVs in VWD patients, these only discuss a small number of CNVs each, and are in varying populations, making it difficult to compare between populations as the differences could be population specific. METHODS: A VWF high-resolution aCGH array was custom designed using long oligonucleotide probes ~60 bp in length to avoid multiple sequence variations, repeated sequences and the pseudogene. Data were manually inspected and analyzed with CytoSure Interpret Software. A multiplex PCR approach was used to map deletion breakpoints and to confirm the presence and zygosity of the deletions in the index case as well as family members. CNVs were mapped and t-tests performed on clinical laboratory values within each VWD type for those with and without a CNV. aCGH was performed in two datasets on low-VWF and VWD index cases with no known pathogenic VWF sequence variant for a total of 205 patients. RESULTS: Of the 205 patients, CNVs were found in 25 (12%). No CNVs were found in low-VWF patients and the only duplication occurred in a Type 2 (n=1) patient. The remaining CNVs were deletions in VWD Type 1+1S (n=12), 1C (n=5), and 3 (n=7) patients. All Type 1C patients (n=5) had the same exon 33-34 deletion. All but 1 of the Type 1+1S patients (n=11) had the same exon 4-5 deletion, while the Type 3 patients (n=7) had deletions spread across the gene. Further, within the Type 1+1S patients, VWFpp/VWF:Ag ratio was significantly lower in those with a CNV than those without (two-tailed t-test, p=0.02). Lastly, ristocetin cofactor was significantly higher in the Type 1C patients with a CNV versus those without a CNV (two-tailed t-test, p=8.2x10-5). DISCUSSION: Here we have analyzed a large dataset of CNVs defined by aCGH in VWD patients with no known pathogenic VWF sequence variant. The location of the deletion in all Type 1C patients exactly matches the D4N module of the D4 domain of the mature VWF protein, a region where mutations and deletions are known to affect clearance. The D4 domain is the only D domain to also include an N module. Although previous work has shown that deletions of exons 33-34 potentially cause a mild reduction in VWF:Ag levels and only a moderate impact on secretion, we observed significantly higher VWF:RCo levels in those Type 1C patients with a CNV when compared to those without. As expected, Type 1C patients had a significantly higher VWFpp/VWF:Ag ratio than Type 1+1S patients overall (p=2.11x10-15). However, the Type 1+1S patient with a CNV had significantly lower VWFpp/VWF:Ag ratio than those without a CNV. This work elucidates some of the underlying genetic mechanisms of CNVs in these patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Molecular and genetic verification of von Willebrand disease type 2N

Introduction. Von Willebrand disease (vWD) is caused by von Willebrand factor (vWF) dysfunction resulting from pathogenic variants in the vWF gene coding the vWF protein. vWD type 2N is of particular interest, as it is characterized by almost normal vWF antigen level (Ag:vWF) and vWF loss of ability to bind FVIII and protect it from premature clearance, which leads to a low FVIII coagulation activity (FVIII:C). Therefore, the same phenotype occurs in patients with 2N type of vWD and hemophilia A.Aim — to identify patients with 2N type vWD using molecular genetic methods.Methods. Data from the medical histories of vWD patients were used. The major parameter in consideration was FVIII:C to vWF:Ag ratio, which is expected to be below 0.7 in type 2N of vWD. Pathogenic variants in exons and exon-intron junctions of the vWF gene were identified by Sanger sequencing. Due to recessive inheritance of type 2N, verification of the 2N vWD diagnosis required the identification of two pathogenic variants.Results. Three patients were considered as suffering from type 2N of vWD according to hemostasis parameters (FVIII:C/vWF:Ag &lt; 0.7). One patient with a preliminary hemophilia A diagnosis was included after sequencing of the F8 gene, which showed no alterations, so 2N type of vWD was suspected. In all cases, sequencing of the relevant functional regions of the vWF gene led to verification of vWD type 2N. One woman (patient # 4) had a homozygous pathogenic variant p.Arg854Gln (c.2561 G&gt;A) associated with type 2N vWD. One woman (patient # 3) was a compound heterozygote for the pathogenic variant p.Arg816Trp (c.2446 C&gt;T) associated with type 2N and a newly described insertion c.2098_2099insG, that leads to a frameshift. The woman with FVIII:C/vWF:Ag &lt; 0.7 (patient # 1) and the patient # 2 with preliminary hemophilia А diagnosis were both compound heterozygotes for the same combination of pathogenic variants — c.2435delC and p.Thr791Met (c.2372 C&gt;T). Pathogenic variant p.Thr791Met is associated with type 2N, while the deletion c.2435delC should lead to allele disabling.Conclusion. Molecular methods allow more precise differentiation of type 2N from other types of vWD and hemophilia A.

S297: ASSESSING THE COST-EFFECTIVENESS OF LONG-TERM PROPHYLAXIS STRATEGIES IN VON WILLEBRAND DISEASE

Background: Von Willebrand disease (vWD) is the most common inherited bleeding disorder. Patients with vWD may experience excessive bleeding events resulting in morbidity, reduced quality of life, and a substantial economic burden. Management strategies include von Willebrand factor concentrates either as on-demand treatment (ODT) of bleeds or long-term prophylaxis (LTP) to prevent bleeds. According to recent treatment guidelines, long-term prophylaxis is recommended in individuals with severe and frequent bleeds. Aims: To assess the cost effectiveness of ODT and LTP treatment strategies in vWD patients with low, medium and high annual bleed rate (ABR), using pdVWF/FVIII 2,4:1 products (2,4:1 product A in the United Kingdom (UK) and 2,4:1 product B in Sweden). Methods: A Markov structure considering risk of joint surgery and bleed rate was used to estimate the life years (LYs), quality-adjusted life years (QALYs), and costs of vWD treatment over a lifetime horizon. Treatment options included ODT or LTP with pdVWF/FVIII 2,4:1 or pdVWF/FVIII 1:1 in the UK and in Sweden. Product dosing for LTP and for ODT were obtained from each product’s summary of product characteristics or assumed equal to similar products where data are not available. Bleed risks (major and minor bleed) were estimated for each product in ODT and LTP using published prophylaxis studies and were used to estimate costs of product needed and to determine the probability of requiring joint surgery over time based on the progression of Pettersson Score. Resource use (inpatient and outpatient) costs for bleeds and joint surgery were obtained from standard country-specific costing sources. All costs are shown in 2021 GBP or Swedish Kr for the UK and Swedish analyses, respectively. Health-state utility weights and disutilities of bleeds were obtained from published literature. Annual discount rates for costs and outcomes were 3.5% for the UK and 3% for Sweden. One-way and probabilistic sensitivity analyses were conducted to evaluate the impact of parameter uncertainty. Each analysis considered a low, medium, and high ABR patient population. Results: In the base case analyses (medium ABR) over a lifetime horizon, pdVWF/FVIII 2,4:1 LTP regimens were cost-effective compared with ODT. For pdVWF/FVIII 2,4:1 in the UK, LTP was both cost-saving (-£831,206 incremental cost) and more effective (6.14 incremental QALY) than ODT. Costs of bleed events more than offset the costs of prophylaxis. In Sweden with pdVWF/FVIII 2,4:1, LTP was also dominant (-8,841,901 kr; 6.52 QALY) compared with ODT. In comparisons of LTP regimens, pdVWF/FVIII 2,4:1 was dominant versus pdVWF/FVIII 1:1 in both the UK (-£2,307,370; 1.56 QALY) and in Sweden (-21,939,947 kr; 1.42 QALY). In comparison of ODT regimens, pdVWF/FVIII 2,4:1 was less expensive than pdVWF/FVIII 1:1 in the UK (-£1,250,369; equal QALY) and in Sweden (-7,923,741 kr; equal QALY) due to differences in product costs. Results were similar for comparisons in the high ABR populations. In probabilistic sensitivity analyses, pdVWF/FVIII 2,4:1 was dominant in over 95% of simulations in the UK and in over 85% of simulations in Sweden, and was cost-effective in 95% or more of simulations in both countries. Summary/Conclusion: These results suggest that LTP with pdVWF/FVIII 2,4:1 is a cost-effective strategy compared with ODT, in both the UK and Sweden, for medium and high ABR vWD patients. pdVWF/FVIII 2,4:1 was shown to be cost-effective compared with pdVWF/FVIII 1:1 in the LTP setting, as well as less costly for patients treated ODT for both the UK and Swedish settings, respectively.

Spectrum of Inherited Bleeding Disorder with Special Reference to von Willebrand Disease in Eastern India.

Background The objective of this study is to study the prevalence, clinical spectrum, and hematological profile of inherited bleeding disorder with special reference to von Willebrand disease in eastern India. Materials and Methods This prospective study was done in a tertiary care center in the eastern part of India over 2 years. Detailed history and clinical findings were noted in a proforma. Laboratory analysis included prothrombin time, activated partial thromboplastin time, bleeding time, and fibrinogen assay along with tests related to specific factor assay. Results One hundred and five patients were diagnosed as suffering with the inherited bleeding disorder out of a total of 1,204 patients. The age of patients ranged from 13 days to 35 years. The most common presenting clinical feature was prolonged bleeding after cut (76.19%). Out of 105 patients, 97 patients (92.38%) had coagulation defect, 5 patients (4.76%) had von Willebrand disease (vWD), and 3 patients (2.85%) had platelet defect. Most common coagulation defect was hemophilia A (84 cases), followed by hemophilia B (8 cases). Other rare congenital factor deficiencies were seen in five cases (5.15%). Only platelet defect was Glanzmann's thrombasthenia (GT). The age of vWD patients ranged from 4.5 years to 24 years. Forty percent patients with vWD disease were type 1 followed by 40% of type 2N and 20% of type 3 vWD. Conclusion vWD was not so common in eastern India. vWD was present only in 4.76% cases in this study. The most common coagulation defect was hemophilia A (86.59%) in our study. GT was present in only 2.85% cases.