M. Bowman

Generation and validation of the Condensed MCMDM-1VWD Bleeding Questionnaire for von Willebrand disease

Summary.  Background: Given the challenges involved in obtaining accurate bleeding histories, attempts at standardization have occurred and the value of quantifying hemorrhagic symptoms has been recognized. Patients/methods: An extensive validated bleeding questionnaire (MCMDM‐1VWD) was condensed by eliminating all details that did not directly affect the bleeding score (BS) and the correlation between the two versions was tested. Additionally, the diagnostic utility of the condensed version was prospectively tested. Results: Data on 259 individuals who were administered the questionnaire are presented here; 217 being prospectively investigated for von Willebrand disease (VWD) (group 1) and 42 previously known to have type 1, 2 or 3 VWD (group 2). Of the 217 prospectively investigated, 35 had positive BS (≥4) and 182 had negative scores. Seven individuals (all with positive BS) had laboratory results consistent with type 1 VWD. This results in a sensitivity of 100% and a specificity of 87%. The positive predictive value is 0.20 and the negative predictive value is 1. The correlation between the full MCMDM‐1VWD and condensed versions is excellent (Spearman’s 0.97, P < 0.001, linear regression r2 = 96.4). Inter‐observer reliability for the condensed version is reasonable (Spearman’s 0.72, P < 0.001 and intra‐class correlation coefficient 0.805, P < 0.001). There was a significant difference in BS between subtypes of VWD, with type 3 >> type 2 >> type 1 VWD (anovaP < 0.001). There is a strong inverse relationship between VWF:Ag level and BS (Spearman’s −0.411, P < 0.001). Conclusions: The Condensed MCMDM‐1VWD Bleeding Questionnaire is an efficient, effective tool in the evaluation of patients for VWD.

Evaluation of the diagnostic utility for von Willebrand disease of a pediatric bleeding questionnaire

1 Warkentin TE, Greinacher A, Koster A, Lincoff AM. American College of Chest Physicians. Treatment and prevention of heparininduced thrombocytopenia: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).Chest 2008 ; 133 (6 Suppl.): 340S–80S. 2 Greinacher A, Warkentin TE. Recognition, treatment, and prevention of heparin-induced thrombocytopenia: review and update. Thromb Res 2006; 118: 165–76. 3 Francis JL. A critical evaluation of assays for detecting antibodies to the heparin-PF4 complex. Semin Thromb Hemost 2004; 30: 359– 68. 4 de Larrañaga G, Martinuzzo M, Bocassi A, Fressart MM, Forastiero R. Heparin-platelet factor 4 induced antibodies in patients with either autoimmune or alloimmune antiphospholipid antibodies. Thromb Haemost 2002; 88: 371–3. 5 Martin-Toutain I, Piette JC, Diemert MC, Faucher C, Jobic L, Ankri A. High prevalence of antibodies to platelet factor 4 heparin in patients with antiphospholipid antibodies in absence of heparin-induced thrombocytopenia. Lupus 2007; 16: 79–83. 6 Jang IK, Marcie JH. When heparin promote thrombosis: review of heparin-induced thrombocytopenia. Circulation 2005; 111: 2671–83. 7 Price EA, Hayward CPM, Moffat KA, More JC, Waerkentin TE. Laboratory testing for heparin-induced thrombocytopenia is inconsistent in North America: a survey of North American specialized coagulation laboratories. Thromb Haemost 2007; 98: 1357–61. 8 Zandecki M, Genevieve F, Gerard J, Godon A. Spurious counts and spurious results on haematology analysers: a review. Part I: platelets. Int J Lab Hematol 2007; 29: 4–20. 9 Bartels PC, Schoorl M, Lombarts AJ. Screening for EDTA-dependent deviations in platelet counts and abnormalities in platelet distribution histograms in pseudothrombocytopenia. Scand J Clin Lab Invest 1997; 57: 629–36. 10 Amiral J, Bridey F, Dreyfus M, Vissoc AM, Fressinaud E, Wolf M, Meyer D. Platelet factor 4 complexed to heparin is the target for antibodies generated in heparin-induced thrombocytopenia. Thromb Haemost 1992; 68: 95–6. 11 Chong BH, Burgess J, Ismail F. The clinical usefulness of the platelet aggregation test for the diagnosis of heparin-induced thrombocytopenia. Thromb Haemost 1993; 69: 344–50. 12 Schwarzinger I, Speiser W, Lubenow N, Greinacher A, Panzer S. Heparin-platelet factor (PF) 4 antibodies in patients with pseudothrombocytopenia: coincidence or association?ThrombHaemost 2000; 84: 1123–4.

Quantitation of bleeding symptoms in children with von Willebrand disease: use of a standardized pediatric bleeding questionnaire.

Summary.  Background: Excessive bruising and mucocutaneous bleeding are frequent presenting symptoms in childhood. A detailed bleeding history can distinguish children who may have an inherited bleeding disorder from those who are normal. There is a lack of standardization of such history taking in pediatric practise. Objectives: To assess the performance of a Pediatric Bleeding Questionnaire (PBQ), an adaptation of a standardized adult bleeding questionnaire and score that includes pediatric‐specific bleeding symptoms, in a cohort of children with von Willebrand disease (VWD). Patients/Methods: Bleeding scores were determined by interview, for children with a previous diagnosis of VWD and a control group of unaffected siblings. Results: Bleeding scores were obtained for 100 children with VWD, median age 10.9 years (range, 0.8–17.8 years), and 21 unaffected siblings. Median bleeding score in children with VWD was 7.0 (range, 0–29) and in the control group was 0 (range, −1–2). Bleeding score varied within and between each VWD type: definite type 1, n = 40, median, 9.0 (range, 2–18); possible type 1, n = 38, median, 2.0 (0–15); type 2, n = 6, median, 14.0 (3–17); and type 3, n = 16, median, 12.0 (4–29). Bleeding scores in affected children correlated with age (Spearman’s correlation coefficient, 0.35; P = 0.0004). The most frequent clinically significant bleeding symptoms were surgical bleeding, bleeding after tooth extraction and menorrhagia. Post‐circumcision bleeding, cephalohematoma, macroscopic hematuria and umbilical stump bleeding were clinically significant in 32% (of circumcised males), 4%, 4% and 3% of children, respectively. Conclusions: The PBQ provides a standardized quantitation of bleeding severity in children with VWD.

Normal range of bleeding scores for the ISTH-BAT: adult and pediatric data from the merging project.

Bleeding Assessment Tools (BATs) have been developed to aid in the standardized evaluation of bleeding symptoms. The Vicenza Bleeding Questionnaire (BQ), published in 2005, established a common framework and scoring key that has undergone subsequent modification over the years, culminating in the publication of the ISTH‐BAT in 2010. Understanding the normal range of bleeding scores is critical when assessing the utility of a BAT. Within the context of The Merging Project, a bioinformatics system was created to facilitate the merging of legacy data derived from four different (but all Vicenza‐based) BATs; the MCMDM1‐VWD BQ, the Condensed MCMDM‐1VWD BQ, the Pediatric Bleeding Questionnaire and the ISTH‐BAT. Data from 1040 normal adults and 328 children were included in the final analysis, which showed that the normal range is 0–3 for adult males, 0–5 for adult females and 0–2 in children for both males and females. Therefore, the cut‐off for a positive or abnormal BS is ≥4 in adult males, ≥6 in adult females and ≥3 in children. This information can now be used to objectively assess bleeding symptoms as normal or abnormal in future studies.

The prevalence of symptomatic von Willebrand disease in primary care practice

The adjusted HR for the development of PTS in thrombophilic as compared with non-thrombophilic patients was 1.23 (95% CI, 0.92–1.64; P = 0.15). In comparison to non-carriers of thrombophilia, the adjusted HR for the development of PTS was 0.42 (95% CI, 0.20–0.88; P = 0.02) in carriers of FVL, 0.81 (0.36–1.37) in carriers of lupus anticoagulant, 0.96 (0.29–3.82) in carriers of protein C deficiency, 1.08 (0.29–2.70) in carriers of protein S deficiency, and 1.33 (0.68–2.58) in carriers of the prothrombin gene mutation. Neither of the two patients with antithrombin deficiency developed PTS. In the subgroup of the 85 patients with FVL, PTS developed in 11 of the 50 patients (22.0%) with involvement of the popliteal vein only, and in 18 of the 35 (51.4%; P = 0.01) with more proximal thrombosis location, irrespective of the modality of clinical presentation (idiopathic or secondary to risk factors). The main limitation of our investigation lies in the failure to assess the role of other thrombophilic abnormalities such as hyperhomocysteinemia and increased levels of factors VIII, IX or XI. Nevertheless, based on our results the PTS rate in carriers of the most common thrombophilic abnormalities who develop an episode of proximal DVT does not seem to exceed that expected in non-carriers, and is likely to be even diminished by the carriage of FVL, most probably because of the more distal location of the thrombotic episode in carriers as compared with non-carriers of this abnormality [3,8]. The main implication of our study results is that awareness of a thrombophilic status should not influence the strategy that is commonly recommended for prevention of late post-thrombotic sequelae in patients with proximal DVT. Disclosure of Conflict of Interests

The effect of exercise on von Willebrand factor and ADAMTS‐13 in individuals with type 1 and type 2B von Willebrand disease

Summary.  Background: The effect of exercise on von Willebrand factor (VWF) and ADAMTS‐13 levels in individuals with von Willebrand disease (VWD) has never been reported.

The genetics of Canadian type 3 von Willebrand disease: further evidence for co-dominant inheritance of mutant alleles.

Type 3 von Willebrand disease (VWD) is the most severe form of the disease and is classically inherited in an autosomal recessive fashion.

A prospective evaluation of the prevalence of symptomatic von Willebrand disease (VWD) in a pediatric primary care population.

The prevalence of von Willebrand disease (VWD) is reported as ∼1%; however, these estimates were not based on individuals with significant symptoms. Four thousand five hundred ninety‐two unselected parents/children were asked: “Does your child have a problem with bleeding/bruising?”; 223 (5%) answered yes, 41 of whom were administered the validated Pediatric Bleeding Questionnaire and had VWF testing. Five were diagnosed with VWD (three type 1, one type 2A, one type 2B). The prevalence of bleeding/bruising in a general pediatric population is 5%; the prevalence of symptomatic VWD at the level of pediatric primary care is at least 1 in 1,000. Pediatr Blood Cancer 2010;55:171–173.

Bleeding Scores for the Diagnosis of von Willebrand Disease.

Abstract Obtaining a personal history of bleeding is a critical component to the diagnosis of von Willebrand disease (VWD). The collection of this information can be challenging for physicians, however, as the reporting and interpretation of bleeding symptoms is subjective. The need for more precise quantification of bleeding symptoms was recognized and the Vicenza Bleeding Questionnaire was developed in 2005. This questionnaire collects data regarding the presence and severity of bleeding symptoms and generates a bleeding score by summing the severity of all symptoms reported by a patient. Several subsequent bleeding assessment tools (BATs) have been developed based from this original questionnaire and there has been a surge in the use of BATs in various clinical settings for the diagnosis and evaluation of VWD. This review will discuss the evolution of BATs over the past decade, as well as their use and validation in various settings for the diagnosis and evaluation of VWD. Additionally, we will discuss the clinical utility of BATs, the limitations of these tools, and future directions.

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

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