Key result
Aspirin resistance was associated with a lower unadjusted likelihood of favorable 90-day outcome (57.8% vs 71.0%; OR 0.69, 95% CI 0.47-0.97) but was not an independent predictor of functional outcome.
Why the study?
Does aspirin resistance predict unfavorable functional outcomes in patients with acute ischemic stroke?
Cohort (n=269)
Does aspirin resistance predict unfavorable functional outcomes in patients with acute ischemic stroke?
Odds Ratio: 0.69 (95% CI 0.47–0.97)
Absolute Event Rate: 57.8% vs 71%
p-value: p=0.037
Aspirin resistance measured by PFA-100 is associated with unfavorable 90-day outcomes in acute ischemic stroke, but is not an independent predictor, likely reflecting a complex interaction of inflammation and prothrombotic activity.
Aspirin resistance should not yet inform prognosis or therapy in acute ischemic stroke; leaves open its independent role amid inflammation and thrombosis.
BACKGROUND: The relationship between biochemical aspirin resistance (AR) and functional outcome of acute ischemic stroke is uncertain. METHODS: Prospectively, 269 patients with acute ischemic stroke were recruited. Their responsiveness to aspirin was evaluated by platelet function analyzer (PFA-100). All patients received blood tests for fibrinogen, high-sensitivity C-reactive protein (hs-CRP), CD40-ligand, P-selectin, intercellular adhesion molecule -1, von Willebrand factor (vWF), and D-dimer. The patients' National Institutes of Health Stroke Scale and modified Rankin Scale scores were recorded on admission, at 30 days, and at 90 days after stroke. RESULTS: Closure-time measured by PFA-100 equipped with epinephrine/collagen cartridge (Epi-CT) was <193 seconds (defined as AR) in 83 patients (30.9%). Patients with AR were less likely to have favorable outcome at 30 days (47.0%, p = 0.047; odds ratio: 0.69, 0.48-0.99) and 90 days (57.8%, p = 0.037; odds ratio: 0.69, 0.47-0.97) after stroke compared with those of patients without AR (60.2% and 71.0%, respectively). The Epi-CT correlated with closure-time measured by adenosine diphosphate/collagen cartridge (r = 0.241, p < 0.001), blood white cell count (r = -0.125, p = 0.041), low density lipoprotein cholesterol (r = 0.120, p = 0.050), hs-CRP (r = -0.150, p = 0.015), vWF (r = -0.134, p = 0.028), and body mass index (r = 0.143, p = 0.019). Multivariate logistic regression analysis showed that higher National Institutes of Health Stroke Scale at admission, atrial fibrillation, increased plasma levels of hs-CRP, and D-dimer were independent predictors for unfavorable stroke outcome at 90 days. CONCLUSION: Aspirin resistance evaluated by PFA-100 test was associated with unfavorable 90-day outcome. However, AR determined by PFA-100 dose not predict 90-day functional outcome. The results of PFA-100 testing represented a complex interaction between drug effect, inflammatory reaction, and prothrombotic activity.
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Lai et al. (2012) conducted a cohort in Acute ischemic stroke (n=269). Aspirin resistance vs. No aspirin resistance was evaluated on Favorable outcome at 90 days (OR 0.69, 95% CI 0.47-0.97, p=0.037). Aspirin resistance was associated with a lower unadjusted likelihood of favorable 90-day outcome (57.8% vs 71.0%; OR 0.69, 95% CI 0.47-0.97) but was not an independent predictor of functional outcome.
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