Variation in Platelet Function Testing Has a Major Influence on Detection of Aspirin Resistance in Healthy Subjects

Abstract

Introduction: An increased demand for monitoring aspirin treatment by platelet function tests has been observed, but data on the biological variation of these tests are insufficient. The aim of this study was to assess the biological variation of optical platelet aggregometry and closure time in healthy subjects without aspirin and after aspirin ingestion. Subjects and Methods: In 20 healthy subjects, blood was sampled 4 times: on 2 consecutive mornings a day after aspirin ingestion (100 mg/daily) and on 2 consecutive days of no treatment. In all samples, arachidonic acid-, ADP- and collagen-induced optical platelet aggregation was measured, and closure times were determined by collagen/epinephrine (CEPI) and collagen/ADP (CADP) cartridges in a platelet function analyzer-100. Results: Aspirin significantly reduced arachidonic acid- and ADP-induced platelet aggregation and significantly prolonged CEPI closure time, but had no significant effect on collagen-induced platelet aggregation and CADP closure time. Aspirin increased both within- and between-subject coefficients of variation. Arachidonic acid-induced platelet aggregation was the most sensitive to aspirin and no aspirin-resistant subjects were detected on either day after aspirin. According to ADP-induced platelet aggregation or CEPI closure time, 25 and 30% of healthy subjects, respectively, changed from aspirin resistant to aspirin responsive or vice versa from one day to another. There was no agreement between platelet function tests in determining aspirin resistance. Conclusions: A significant variation in optical platelet aggregometry and closure time exists and is presumed to have a major effect on determination of aspirin resistance.

Biologic variability and correlation of platelet function testing in healthy dogs

“…In the present study, the degree of CV G greatly exceeded the CV I for all platelet function tests except for PFA‐CADP, potentially allowing for the results of diseased and healthy dogs to overlap . This likely reflects the heterogeneous response of platelets to various agonists previously reported in dog populations, and is consistent with findings in people . The relatively large CV G identified with most platelet function tests in this study is further emphasized when the indices of individuality are calculated .…”

“…While the biologic variability of platelet function testing in dogs with platelet abnormalities has not been studied, dogs with severe hemophilia A (< 1% FVIII activity) had significantly higher CV G and CV I for TEG variables compared to normal dogs . Additionally, some human studies showed that aspirin increases variability in platelet function test results …”

A comparison of platelet function tests and thromboxane metabolites to evaluate aspirin response in healthy individuals and patients with coronary artery disease

“…For all tests, CVs were higher during aspirin treatment than at baseline. This finding is in accordance with a previous study showing that aspirin increases the variation in test results (10). The repeatability of the traditional reference method according to the literature was not impressive.…”

“…Unfortunately, there is no consensus on how to measure the effect of aspirin on platelet aggregation. Light transmission aggregometry (LTA) is considered the gold standard for evaluation of platelet aggregation (9)(10)(11). Nevertheless, LTA is non-physiological and time-consuming and, consequently, whole blood tests have been developed.…”

Pre-analytical effects of pneumatic tube transport on impedance platelet aggregometry

“…However, a more recent study also using PFA-100 Õ failed to find such an effect [9]. Rather small absolute differences and large variability in test results in platelet function analyzers may have contributed to the conflicting findings as well as different pre-analytical handling of the probes [13,14,29]. In contrast to previous studies, we used hirudin as an anticoagulant, which may be preferable to both sodium citrate or heparin because both influence platelet function [14,30,31].…”