title: Variability of non-response to aspirin in patients with peripheral arterial occlusive disease during long-term follow-up.
abstract: Non-responsiveness to aspirin as detected by laboratory tests may identify patients at high risk for future vascular events. The aim of this prospective study was to evaluate whether non-responsiveness to aspirin is stable over time. Ninety-eight patients with stable peripheral arterial occlusive disease (PAOD) treated with 100 mg/d aspirin were followed over a median timeframe of 17 months. Platelet function tests were performed initially and at follow-up using arachidonic acid-induced light transmittance aggregometry (LTA) in native platelet-rich plasma with the Behring Coagulation Timer and by measuring the collagen-epinephrine closure time (CT) on a Platelet Function Analyzer (PFA-100). When determining platelet function using LTA, four patients (4.1%) had residual platelet function (i.e., MaxAggr > or =78%) despite aspirin treatment, whereas, according to the PFA-100 results, 12 patients (12.2%) were identified as non-responders (i.e., CT <192 s). Fifty-seven patients who were still under treatment with 100 mg/d aspirin at the time of follow-up provided a second blood sample. Further platelet function tests with the PFA-100 system identified a persistent non-responsiveness to aspirin over time in three patients (5.3%) whereas four (7.0%) and 15 (26.3%) patients had changes in response status when platelet function was assessed by LTA and on the PFA-100(R), respectively. We conclude that true non-responsiveness to aspirin is a rare phenomenon in stable PAOD patients. Furthermore, we conclude that in a number of patients, aspirin non-responsiveness is not stable over time.
authors.affiliation: Department of Internal Medicine, Division of Vascular Medicine, J.W. Goethe University Hospital, Theodor-Stern-Kai 7, D-60590, Frankfurt/Main, Germany. Birgit.Linnemann@kgu.de
authors.forename: Birgit
authors.initials: B
authors.lastname: Linnemann
authors.forename: Stephanie
authors.initials: S
authors.lastname: Prochnow
authors.forename: Helen
authors.initials: H
authors.lastname: Mani
authors.forename: Jan
authors.initials: J
authors.lastname: Schwonberg
authors.forename: Edelgard
authors.initials: E
authors.lastname: Lindhoff-Last
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001157:Arterial Occlusive Diseases / Q000188:drug therapy*; D001241:Aspirin / Q000008:administration & dosage / Q000494:pharmacology*; D004351:Drug Resistance; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000188:drug therapy*; D010979:Platelet Function Tests / Q000379:methods; D015995:Prevalence
chemical_list: D001241:Aspirin