Platelet function analyser (PFA‐100) results and von Willebrand factor deficiency: a 16‐year ‘real‐world’ experience

Abstract

The platelet function analyser (PFA-100) is a biological tool designed to explore primary haemostasis. This system has thus been widely demonstrated as reliable in detecting von Willebrand factor (VWF) deficiency. However, most studies were based on patients benefitting from regular medical care and accurate diagnosis, and it would seem probable that the results were somewhat optimistic, and do not reflect its performances in 'real-world' situations. We have chosen to study the reliability of PFA-100 for screening VWF ristocetin cofactor (VWF:RCo) deficiency. We retrospectively analysed the results (n = 6431) of 4027 patients referred to our centre between October 1997 and June 2013 and in whom PFA-Epi, PFA-ADP, and VWF:RCo activity had been evaluated. We studied the influence of blood group on the results and the performances of each method in a subgroup of 213 patients with genetically confirmed von Willebrand disease. We have shown that the PFA-100 system, in our experience, constitutes an excellent screening test for detecting VWF:RCo deficiency, whatever the clinical situation, in 'real-world' conditions. The negative predictive value (NPV), the positive predictive value, the sensitivity and the specificity were respectively: 0.98, 0.51, 0.98 and 0.40. When values adjusted for blood group are used, NPV and sensitivity are inferior to those using normal values which have not been adjusted for blood group. We have shown the PFA-100 method to be more efficient in screening for VWF deficiency than the VWF:RCo technique.

Comprehensive re‐evaluation of historical von Willebrand disease diagnosis in association with whole blood platelet aggregation and function

“…These VWF‐dependent platelet function analyses are performed without additional technical manipulation, and PFA enables the measurement of the impact of high shear stress blood. In our study, prolonged CT with PFA was detected in all VWD types, supporting the inclusion of platelet contribution and the use of this assay, among conflicting previous reports . These tests can add value as screening tools and provide support for challenging diagnostics.…”

“…No blood flow and shear force‐based clinical assays are in routine use. The role of the platelet function analyzer PFA‐100 ® (PFA), a primary hemostasis screening tool under high shear stress, is under debate . Multiplate ® (Multiplate) is a next‐generation automated whole blood aggregometry device that does not require additional technical manipulation .…”

The Platelet Function Analyser (PFA)‐100 and von Willebrand disease: a story well over 16 years in the making

“…Interestingly, the first publication on the Thrombostat-4000 only appeared two years earlier, in 1993 [17]. It is therefore fitting that the current issue of Haemophilia includes a contribution [18] on the PFA-100 from a French group who first wrote of their initial experience with this instrument in 1998 [7]. A recent Medline search of 'Thrombostat-4000' yielded only 23 papers; these were published in the period 1993-2001 (a total of 9 years).…”

“…For example, using local external quality assessment (EQA) data, the inter-laboratory coefficient of variation (CV) for VWF:RCo averaged~50% for samples tested in the last decade [2]. Although these CVs reflect inter-laboratory variation, and the data from Ardillon et al [18] report on a single laboratory, one could propose that intra-laboratory variation, plus intra-individual variation, may also be either comparable, or perhaps even favourable for the PFA-100, depending on the method in use for the VWF:RCo. For the PFA-100, there is only the one instrument, and generally only two cartridges used for VWD testing.…”

Abnormal platelet activity in dogs and cats – impact and measurement

“…In people, the PFA is used as a screening test for vWD (Ardillon et al . ). One study reported increased CTs in 2 dogs with vWD that responded to DDAVP treatment (Burgess et al .…”