Correlation of Clinical and Laboratory Aspirin Resistance: A Pilot Study

Aspirin resistance may be biochemical or clinical. Data related to the presence of aspirin resistance in the Indian population is scarce. We conducted a cross sectional study to address the issue of clinical aspirin non responsiveness and to assess the association between inhibition of platelet aggregation, clinical risk factors and occurrence of vascular events. We studied platelet aggregation by optical aggregometry in 20 patients on aspirin. No patient was found to be aspirin-resistant on the basis of pr eviously defined criteria. This led us to relook at the current cut offs for resistance, and an analysis of 60 normal patients showed lower cut off values suggesting ethnic variabil ity. The data was reanalyzed using these cutoffs. An association between poor clinical aspirin response, older age, male sex, smoking and dyslipidemia was found, suggesting a trend, though not significant. 25% of patients had vascular events on aspirin sugges ting clinical aspirin resistance. A lower cut off value for aspirin resistance in normal Indians may be needed to detect true prevalence of this entity. In patients with mul tiple atherothrombotic risk factors lab detection of resistance may be useful in identifyi ng patients with high risk for recurrent vascular events. This may help to modify antiplatelet therapy to prevent vascular events.