Aspirin nonresponders in patients with ischaemic stroke.

From previous studies, the prevalence of aspirin nonresponders is 5.5-45% in patients with various cardiovascular diseases. Those who have aspirin nonresponders have a greater risk of clinically cardiovascular events. The purpose of the study was to look for the prevalence, associated factors and the outcomes of aspirin nonresponders among patients with ischaemic stroke. Patients with ischaemic stroke who were treated during January 2011-August 2011 were included. Urine 11-dehydro-thromboxane B2 (dTXB2) was measured to determine the response to aspirin in patients. The demographics and vascular risk factors were compared between patients who were classified as aspirin responders or aspirin nonresponders. The outcomes of the study were favourable outcome, cardiovascular events and mortality. There were 182 patients included during the study period: 128 patients with an acute ischaemic stroke and 54 patients with a stable ischaemic stroke. Ninety patients (49.5%) were found to be aspirin nonresponders. Multivariate analysis revealed that stroke presentation (acute stroke) was the only factor associated with aspirin nonresponders [odds ratio (OR) 2.38, 95% confidence interval (CI) 1.193-4.746, P = 0.014]. With a mean follow-up time of 16 months, aspirin nonresponders had a less favourable outcome (54 vs. 83%, OR 0.24; 95% CI 0.11-0.51, P < 0.001), marginally higher cardiovascular events (11 vs. 2%, OR 4.48; 95% CI 0.92-21.37, P = 0.045) and higher mortality (12 vs. 1%, OR 10.52; 95% CI 1.3-85.28, P = 0.007). The prevalence of aspirin nonresponders was rather high in Thai patients with ischaemic stroke. Aspirin nonresponders had a less favourable outcome, higher cardiovascular events and death rate.