The prevalence and associated factors of aspirin resistance among prophylactic aspirin users

Abstract

Background. Aspirin is an antiplatelet used for the secondary prevention after vascular events. It is also suggested for the primary prevention of vascular events in high risk people, however, despite using standard prophylactic doses, aspirin resistance may result in therapeutic failure and arterial thrombosis. Since the prevalence of aspirin resistance and its associated factors were heterogeneous in different studies, this study was conducted to determine the prevalence and associated factors of aspirin resistance in an Iranian population under aspirin for primary prevention of vascular events. Methods. 264 patients without documented vascular disease with 80 mg daily aspirin consumption for at least one month enrolled in this cross-sectional study. Aspirin resistance was assessed by the measurement of thromboxane B2 in the urine samples using the enzyme-linked immunosorbent assay method. Aspirin resistance was defined as a urine level of thromboxane B2 ≥ 1700 ng/dl. Results. The prevalence of aspirin resistance in this study was 9.8%. Age (OR = 0.935, 95% CI: 0.880-0.993, P = 0.028) and geographical regions (OR = 0.117, 95% CI: 0.014-0.958, P = 0.045) showed independent correlation with aspirin resistance. No significant association observed between aspirin resistance and gender, diabetes mellitus, hypertension, hyperlipidemia, smoking, duration of aspirin use, body mass index, and drug history. Conclusions. Despite the standard daily dose of aspirin for primary prevention of vascular events, some of our patients exhibited aspirin resistance that was directly related to a higher age and geographical region. More studies are required to clarify the beneficial role of aspirin resistance test before planning a preventive strategy in high risk individuals.

Keywords

• aspirin
• aspirin resistance
• primary prevention
• stroke
• cardiovascular disease
• urine thromboxane b2