Generation and Optimization of the Self-Administered Bleeding Assessment Tool
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Defects in haemostasis, specifically in the quantitative or qualitative properties of von Willebrand factor (VWF), result in the most commonly inherited bleeding disorder, von Willebrand disease (VWD). Of the three types of VWD, type 1 is the most common and has the mildest phenotype. Type 1 VWD has a symptomatic prevalence of approximately 1 in 1000, but a much smaller number of patients who are actually diagnosed. This discrepancy is a result of a lack of standardized diagnostic criteria. The objective of the Self-Administered Bleeding Assessment Tool (Self-BAT) Study is to develop and optimize, a standardized, self-administered BAT to quantify bleeding history, and to distinguish between normal and abnormal bleeding. In Phase 1 of the study, the medical terminology in the expert-administered ISTH BAT was changed to a grade four reading level to produce the first version of the Self-BAT. Three subsequent versions of the Self-BAT were generated during optimization based on focus group feedback and statistical analysis. The Self-BAT was administered to a total of 38 control subjects and 20 subjects affected with type 1 VWD in Phase 1. Demographic information on all the subjects (gender, age) was collected and blood was drawn for determination of VWF antigen level, VWF ristocetin cofactor activity and factor VIII level. Bleeding scores calculated from the ISTH BAT and Self-BAT showed an excellent correlation of 0.869 in the final version. In Phase 2 of the study, the Self-BAT was administered to 27 control subjects and 23 affected subjects with the objective to simplify the questionnaire by identifying questions which can discriminate between unaffected and affected subjects. It was determined through category-total, category-category and item-item correlations that there was not sufficient evidence to reduce the Self-BAT. In conclusion, the Self-BAT functions as a simple and effective tool to distinguish between normal and abnormal bleeding and is suitable for adults to administer themselves. The Self-BAT has now moved on to prospective validation studies where it will be tested on subjects who have been referred to tertiary care, but not yet received a diagnosis, in order to test its ability to distinguish between normal individuals and those affected with type 1 VWD and, potentially, other mild bleeding disorders.