Platelet Function Analyzer-100 Shows Poor Predictive Value for Children with Low VWF and Mild Platelet Function Defects

• Published in: Blood 2020-11, Vol.136 (Supplement 1), p.28-29
• Main Authors: Brown, Megan C., Woods, Gary
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2020-142103

▪ Background: The Platelet Function Analyser (PFA)-100 (Siemens) has proven to be a useful screening tool for primary hemostasis. Studies have demonstrated a pooled sensitivity around 90% for all individuals with Von Willebrand Disease (VWD), however the sensitivity for Type 1 is notably poorer than types 2 and 3. Our institution utilizes the PFA-100 as part of a panel of laboratory studies called the “bleeding screen”; this panel is often used as first line screening for inherited bleeding disorders across the hospital system. As the relative frequency of Type 1 VWD and low VWF (defined as Von Willebrand factor (VWF) levels 30-50%) greatly exceed the frequency of individuals with Type 2 and Type 3, when used as a general screen, the PFA-100 likely has reduced sensitivity than documented in the literature. Methods: To evaluate the utility of the PFA-100 as a screening test for VWD and platelet function defects, we retrospectively examined the ordering practices of PFA-100 in relation to the Von Willebrand panel (VWF:antigen, VWF:ristocetin cofactor, Factor VIII), platelet aggregation studies and platelet electron microscopy. We compared results of the testing with diagnostic codes to characterize the test characteristics of the PFA-100 for the diagnosis of VWD or platelet function defects in a pediatric population. We included all patients tested with the PFA-100 from 2017 to 2018 at any Children’s Healthcare of Atlanta facility. Exclusion criteria include age under 30 months (reference range established for those over 30 months), hematocrit