Predictors of von Willebrand disease in children

Higher rates of bleeding and use of treatment products among young boys compared to girls with von Willebrand disease

There are limited observational studies among children diagnosed with von Willebrand Disease (VWD). We analyzed differences in bleeding characteristics by sex and type of VWD using the largest reported surveillance database of children with VWD (n = 2712), ages 2 to 12 years old. We found that the mean ages of first bleed and diagnosis were lowest among children with type 3 VWD. It was even lower among boys than girls among all VWD types, with statistically significant difference among children with type 1 or type 3 VWD. Children with type 3 VWD also reported higher proportions of ever having a bleed compared to other VWD types, with statistically higher proportions of boys compared to girls reporting ever having a bleed with type 1 and type 2 VWD. A similar pattern was observed with the use of treatment product, showing higher usage among type 3 VWD, and among boys than girls with type 1 and type 2 VWD. While there were no differences in life quality or in well-being status by sex, children with type 3 VWD showed a greater need for mobility assistance compared to children with type 1 and type 2 VWD. In an adjusted analysis among children with type 1 VWD, boys showed a significant association of ever bleeding [hazard ratio 1.4; P-value <.001)] compared to girls. Understanding phenotypic bleeding characteristics, well-being status, treatment, and higher risk groups for bleeding among pre-adolescent children with VWD will aid physicians in efforts to educate families about bleeding symptoms.

A two-center retrospective review of the hematologic evaluation and laboratory abnormalities in suspected victims of non-accidental injury

Investigation for bleeding disorders in the context of suspected non-accidental injury (NAI) is inconsistent. We reviewed the hematologic evaluation of children who presented with symptoms of bleeding and/or bruising suspicious for NAI to determine the frequency of hematologic tests, abnormal hematologic laboratory results, and hematologic diagnoses. A retrospective cohort study design was employed at two freestanding academic children's hospitals. ICD-9 codes for NAI were used to identify 427 evaluable patients. Medical records were queried for the details of clinical and laboratory evaluations at the initial presentation concerning for NAI. The median age for the population was 326 days (range 1 day-14 years), 58% were male. Primary bleeding symptoms included intracranial hemorrhage (31.8%) and bruising (68.2%). Hematologic laboratory tests performed included complete blood cell count in 62.3%, prothrombin time (PT) in 55.0%, and activated partial thromboplastin time (aPTT) in 53.6%; fibrinogen in 27.6%; factor activity in 17.1%; von Willebrand disease evaluation in 14.5%; and platelet function analyzer in 11.7%. Prolonged laboratory values were seen in 22.5% of PT and 17.4% of aPTT assays; 66.0% of abnormal PTs and 87.5% of abnormal aPTTs were repeated. In our cohort, 0.7% (3 of 427) of the population was diagnosed with a condition predisposing to bleeding. In children with bleeding symptoms concerning for NAI, hemostatic evaluation is inconsistent. Abnormal tests are not routinely repeated, and investigation for the most common bleeding disorder, von Willebrand disease, is rare. Further research into the extent and appropriate timing of the evaluation is warranted.

The Prevalence of von Willebrand Disease and Significance of in Vitro Bleeding Time (PFA-100) in von Willebrand Disease Screening in the İzmir Region

Objective: von Willebrand disease (vWD) is the most common hereditary bleeding disorder. The purpose of this investigation was to determine the prevalence of vWD among adolescents in İzmir and to assess the sensitivity and specificity of PFA-100 as a screening method in detecting this disease.

Material and Methods: Our study was conducted on adolescents in the city of İzmir between October 2006 and March 2007. A total of approximately 1500 high school students between 14 and 19 years of age were planned to be included in the investigation. Survey forms prepared for assessing hemorrhagic diathesis were completed by 1339 individuals (512 males, 827 females). The necessary laboratory tests were performed after having obtained written informed consent from 40 individuals suspected to have hemorrhagic diathesis.

Results: Based on the von Willebrand factor antigen (vWF:Ag) and ristocetin cofactor activity (vWF:RCo) levels and bleeding symptoms, vWD type-1 was diagnosed in 14 individuals (4 males, 10 females; prevalence: 1.04%). The most common bleeding symptom in these patients was found to be epistaxis (10/14). Screening with PFA-100 revealed prolongation in both cartridges (Col/ADP and Col/Epi) in 3 of the 14 patients. PFA-100 was determined to exhibit 21.4% sensitivity and 100% specificity in the diagnosis of vWD.

Conclusion: The PFA-100 device was found to have high specificity but to have exhibited low sensitivity. Therefore, its utilization as a screening test may be problematic in patients with mild type-1 vWD. Specific tests (vWF:RCo, vWF:Ag) are required for the definite diagnosis of vWD. However, further studies with a large number of patients are needed.

Conflict of interest:None declared.

The evolution and value of bleeding assessment tools

A personal history of excessive mucocutaneous bleeding is a key component in the diagnosis of a number of mild bleeding disorders, including von Willebrand disease (VWD), platelet function disorders (PFD), and coagulation factor deficiencies. However, the evaluation of hemorrhagic symptoms is a well-recognized challenge for both patients and physicians, because the reporting and interpretation of bleeding symptoms is subjective. As a result, bleeding assessment tools (BATs) have been developed and studied in a variety of clinical settings. This work has been pioneered by a group of Italian researchers, and the resultant 'Vicenza Bleeding Questionnaire' stands as the original BAT. In this review, we will discuss the modifications of the Vicenza Bleeding Questionnaire that have taken place over the years, as well as the validation studies that have been published. Other BATs that have been developed and published will be reviewed, as will the special situations of assessing pediatric bleeding as well as menorrhagia. Lastly, the clinical utility of BATs will be discussed including remaining challenges and future directions for the field.

Phenotyping bleeding

PURPOSE OF REVIEW

Although recorded evidence of phenotyping bleeding disorders extends back two millennia, standardization of phenotyping has only begun in the past half century. This was spurred by the need for greater precision in diagnosing disorders in order to select proper laboratory tests and treatment, and the realization that the bleeding history provides prognostic information about the future risk of bleeding with surgery or invasive procedures.

RECENT FINDINGS

New bleeding assessment tools (BATs) have been developed, firstly, to evaluate the relative bleeding risks associated with new anticoagulants and antiplatelet agents, secondly, to assess the efficacy of new thrombopoiesis stimulating agents in preventing hemorrhage in patients with immune thrombocytopenia, and finally, to assess complex gene-gene and gene-environment interactions. New web-based systems allow many researchers to collaborate by sharing the same electronic phenotyping infrastructure. Major issues of validation remain, but at present the data indicate that the new BATs have relatively high negative predictive value for excluding a significant bleeding disorder, but disappointingly low positive predictive values.

SUMMARY

New instruments to phenotype bleeding have been developed to address a number of different important clinical and research goals. The improved standardization and opportunities for collaborative studies hold promise for maximizing diagnostic, prognostic, and scientific information.