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Electronic letters published:
![[Read Rapid Response]](/icons/misc/sectionDOWN.gif){kind=icon}
Aspirin Resistance and Its Clinical Implications
Testing for Aspirin Resistance
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Wai-Hong Chen, MBBS, FACC Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China
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whchen{at}hku.hk Wai-Hong Chen
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To the editor: I read with interest the review entitled “Narrative Review: Aspirin Resistance and Its Clinical Implications” by Sanderson et al in the March 2005 issue of Annals of Internal Medicine. While I agree with the authors that it is important to understand and compare different measures of platelet activation in defining this term, I was surprised by the fact that one newer assay, VerifyNow Aspirin (Accumetrics, San Diego) was lumped in Table 2 with an older test the PFA-100, incorrectly described, and ignored in the body of the review. Our group and others have been involved in clinical trials and published (1-3) on this instrument. We demonstrated that this system correlated to clinical outcomes (3), which is important to show for these laboratory measures of platelet function. In addition, there is an excellent comparative review of the strengths and weaknesses of this and various methods by Michelson in a recent issue of Circulation (4). References 1. Wang JC, Aucoin-Barry D, Manuelian D, Monbouquette R, Reisman M, Gray W, Block PC, Block EH, Ladenheim M, Simon DI. Incidence of aspirin nonresponsiveness using the Ultegra Rapid Platelet Function Assay-ASA. Am J Cardiol. 2003;92:1492-4. 2. Coleman JL, Wang JC, Simon DI. Determination of Individual Response to Aspirin Therapy Using the Accumetrics Ultegra RPFA-ASA System. Point of Care 2004;3:77–82. 3. Chen WH, Lee PY, Ng W, Tse HF, Lau CP. Aspirin resistance is associated with a high incidence of myonecrosis after non-urgent percutaneous coronary intervention despite clopidogrel pretreatment. J Am Coll Cardiol. 2004;43:1122-6. 4. Michaelson AD. Platelet function testing in cardiovascular diseases. Circulation 2004 Nov 9;110(19):e489-93. Conflict of Interest:None declared |
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Robert E Hoyt, MD Uniformed Services University of the Health Sciences
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rehoyt{at}cox.net Robert E Hoyt
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In the review by Sanderson et al on aspirin resistance they state that testing urine thromboxane B2 levels is both simple and inexpensive but they don't recommend routine biochemical testing. It should be pointed out that the test is not inexpensive according to several reference laboratories. For example, the cost to perform the test by Quest Diagnostics (www.questdiagnostics.com) is $375. Cost should be added to the several limitations of this test of aspirin resistance. Robert Hoyt MD Assistant Professor of Medicine and Family Practice Uniformed Services University of the Health Sciences Simon Sanderson, Jon Emery, Trevor Baglin, and Ann-Louise Kinmonth Narrative Review: Aspirin Resistance and Its Clinical Implications Ann Intern Med 2005; 142: 370-380 Conflict of Interest:None declared |
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