External Quality Assessment Data for Investigation of von Willebrand Disease: Focus on Relative Utility of Contemporary Functional von Willebrand Factor Assays. The United Kingdom National External Quality Assessment Scheme (UK NEQAS) Experience

Jennings, Ian; Reilly-Stitt, Chris; Lowe, Anna; Kitchen, Steve; Walker, Isobel D.

doi:10.1055/s-0042-1753512

Cited by 7 publications

(33 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The current report adds to data from previous reports of the RCPAQAP 14 35 36 37 38 39 40 41 42 as well as from other EQA providers. 22 23 24 25 26 The summarized contemporary data (past 9 years) is shown for a large quantity of samples ( n = 31) of assorted type, which have been cross-laboratory assessed by “real world” laboratories, with some focus applied to the discrimination of samples deficient in VWF (“type 1”) from those deficient in HMW-VWF (“type 2”). Despite occasional outlier results (examples shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Evaluating Performance of Contemporary and Historical von Willebrand Factor (VWF) Assays in the Laboratory Identification of von Willebrand Disease (VWD): The Australasian Experience

Favaloro

Dean

Arunachalam

2022

Semin Thromb Hemost

View full text Add to dashboard Cite

Abstractvon Willebrand disease (VWD) is a common bleeding disorder that arises from deficiency and/or defects of von Willebrand factor (VWF). Appropriate diagnosis of VWD, including differential identification of qualitative (types 2A, 2B, 2M, 2N VWD) versus quantitative (types 1 and 3 VWD) defects remains problematic but has important management implications, given differential therapy. Complete assessment for VWD in a patient with a bleeding history requires comprehensive test panels, including VWF activity and antigen. We describe the Australasian experience, using data from the Royal College of Pathologists of Australasia (RCPA) Quality Assurance Program (QAP) related to VWF testing in their VWD test module. The RCPAQAP has been providing samples for VWF testing since 1998, representing 25 years of proficiency testing related to VWD diagnosis. A total of 109 samples have been dispatched to participants over these years, with current assessment involving dispatches of two samples (=4 samples) per year. Samples have represented all types of VWD, as well as normal or other samples, including acquired von Willebrand syndrome and plasma VWF concentrates as used in VWD therapy. Different VWF assays and activity/antigen ratios show different utility in VWD and type identification. In the past 9 years of data capture, a total of 166 errors were identified from a total of 1,839 interpretations, representing a base error rate of 9.0%. Identification errors were highest for type 2 VWD samples (15.3%), intermediate for type 1 VWD samples (7.5%), and lowest for normal samples (2.4%). Errors can be linked to assay limitations, including assay variability and low-level VWF detection limits, as well as laboratory issues (including test result misinterpretation, which accounts for approximately 40% of all errors for type 2 VWD). For test-associated errors, VWF:RCo and VWF:GPIbM were associated with the highest variability and error rate, which was up to 10x higher than that using VWF:CB. As a test group, chemiluminescence-based procedures were associated with lowest inter-laboratory variability, best low-level VWF detection (down to <1 U/dL), and least errors overall. These findings inform on reasons behind high rates of errors associated with VWD diagnosis, with some assays and methodologies performing substantially better than others.

show abstract

Section: Discussionmentioning

confidence: 99%

Evaluating Performance of Contemporary and Historical von Willebrand Factor (VWF) Assays in the Laboratory Identification of von Willebrand Disease (VWD): The Australasian Experience

Favaloro

Dean

Arunachalam

2022

Semin Thromb Hemost

View full text Add to dashboard Cite

show abstract

“…and NASCOLA 18 data. Users of VWF:CB are prominent in RCPAQAP 14 and ECAT 19 data, followed by NEQAS 17 and NASCOLA 18 data, but limited in CAP 16 data.…”

Section: Learning From Eqamentioning

confidence: 99%

“…The other programs did not specifically report on diagnostic errors, but may instead report on participant interpretation for separate individual assays (e.g., normal vs. abnormal). 16,17,18,19 Tests and Test Panels Used across Different Geographies…”

Section: Errors In Vwd Diagnosismentioning

confidence: 99%

Laboratory Diagnosis of von Willebrand Disease (VWD): Geographical Perspectives

Favaloro

Pasalic

2022

Semin Thromb Hemost

View full text Add to dashboard Cite

Abstractvon Willebrand disease (VWD) is reportedly the most common inherited bleeding disorder, and can also arise as an acquired (von Willebrand) syndrome (AVWS). The hemostasis laboratory plays a key role in the diagnosis or exclusion of VWD/AVWS, which may otherwise be suspected due to the patient's clinical (bleeding) history. VWD/AVWS arise from deficiency and/or defects in the adhesive plasma protein, von Willebrand factor (VWF). VWF undertakes various roles within hemostasis, but principally acts within primary hemostasis to anchor platelets to sites of vascular damage, thereby facilitating thrombus formation to arrest bleeding. The diagnosis or exclusion of VWD/AVWS requires laboratory testing for both VWF level and activity, with the latter potentially comprising several of a potential plethora of different assays. Complete diagnosis of VWD also requires the differentiation of VWD type, with six types comprising the current classification (i.e., qualitative [types 2A, 2B, 2M, 2N VWD] vs. quantitative [types 1 and 3 VWD] deficiency/defects). Although appropriate diagnosis and type classification hold important therapeutic consequences, these remain problematic and sometimes elusive for some laboratories to achieve. This report reviews the laboratory aided diagnosis or exclusion of VWD from a geographic perspective, and focuses on the disparities of approaches and methods in different regions of the world. This is primarily done from the perspective of data available from published reports related to external quality assessment (or proficiency testing) from different geographic localities. Moreover, differences in approaches between laboratories may arise due to differential adherence of particular guidelines, as well as regulatory aspects and predominance of local manufacturers and suppliers.

show abstract

“…An example of European VWF EQA experience comes from the contribution by Jennings et al that summarizes data from the United Kingdom National External Quality Assessment Scheme (UK NEQAS). 11 This group again emphasizes the importance of VWF assay calibration and impacts on VWF activity/antigen ratios and diagnostic cutoffs. The authors point out that international standard ISTH Lot 5 began assigning values for specific VWF activity assays, such as VWF:GPIbM and VWF:GPIbR, 21 acknowledging that different VWF assays can indeed produce different results.…”

mentioning

confidence: 99%

“…The VWF papers are a special collection of updates on VWF testing patterns and assay performance and quality contributed by authors representing five external quality assessment (EQA) programs operating in North America, Europe, and Australasia. [8][9][10][11][12][13] For those less familiar, EQA participation is an important component of quality laboratory practice and required by regulatory agencies. EQA organizations challenge laboratories to test blinded lyophilized plasma specimens representing the normal condition or a disease process, in this case primarily von Willebrand disease (VWD).…”

mentioning

confidence: 99%