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Aspirin ‘resistance’: role of pre‐existent platelet reactivity and correlation between tests
Author(s) -
FRELINGER A. L.,
LI Y.,
LINDEN M. D.,
TARNOW I.,
BARNARD M. R.,
FOX M. L.,
MICHELSON A. D.
Publication year - 2008
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2008.03184.x
Subject(s) - aspirin , platelet , medicine , arachidonic acid , thromboxane , thromboxane b2 , chemistry , biochemistry , enzyme
Summary. Background: Aspirin ‘resistance’ is a widely used term for hyporesponsiveness to aspirin in a platelet function test. Serum thromboxane (TX) B 2 is the most specific test of aspirin’s effect on platelets. Objectives: (i) To examine the role of pre‐existent platelet hyperreactivity in aspirin ‘resistance’. (ii) To determine the correlation between aspirin resistance defined by serum TXB 2 and other assays of platelet function. Methods: To enable pre‐aspirin samples to be drawn, platelet function was measured in normal subjects ( n = 165) before and after aspirin 81 mg daily for seven days. Results: The proportion of the post‐aspirin platelet function predicted by the pre‐aspirin platelet function was 28.3 ± 7.5% (mean ± asymptotic standard error) for serum TXB 2 , 39.3 ± 6.8% for urinary 11‐dehydro TXB 2 , 4.4 ± 7.7% for arachidonic acid‐induced platelet aggregation, 40.4 ± 7.1% for adenosine diphosphate‐induced platelet aggregation, 26.3 ± 9.2% for the VerifyNow Aspirin Assay ® , and 45.0 ± 10.9% for the TEG ® PlateletMapping™ System with arachidonic acid. There was poor agreement between aspirin‐resistant subjects identified by serum TXB 2 vs. aspirin‐resistant subjects identified by the other five assays, irrespective of whether the analysis was based on categorical or continuous variables. Platelet count correlated with pre‐aspirin serum TXB 2 and VerifyNow Aspirin Assay, but not with any post‐aspirin platelet function test. Conclusions: (i) Aspirin ‘resistance’ (i.e. hyporesponsiveness to aspirin in a laboratory test) is in part unrelated to aspirin but is the result of underlying platelet hyperreactivity prior to the institution of aspirin therapy. (ii) Aspirin resistance defined by serum TXB 2 shows a poor correlation with aspirin resistance defined by other commonly used assays.