Effect of Aspirin on platelet aggregation among patients with ischemic stroke and healthy volunteers at the Kenyatta National Hospital
Background: Use of Aspirin in ischemic stroke has been shown to reduce the risk of recurrent arterio-thrombotic events by up to 25%. Up to 30- 40% of patients with ischemic events have been shown to pe resistant to aspirin by in-vitro tests. Aspirin non responders have a fourfold risk of recurrent ischemic events. The prevalence of aspirin resistance among ischemic stroke patients has not been evaluated in Kenyatta National Hospital. Study objective: To determine the effect of aspirin on platelet aggregation among patients with ischemic stroke and healthy volunteers at Kenyatta National Hospital. Methodology: The study applied a descriptive cross-sectional design. A random sample of 142 ischemic stroke patients and 62 healthy Volunteers at Kenyatta national hospital received 300mg of Bayer ECﾮ aspirin. Optic platelet aggregation was then carried out with 10llM ADP and 0.5mg/ml AA as agonists 4 hours after aspirin therapy. Aspirin non response was defined as platelet aggregation~200/0 with Arachidonic Acid and ~70% with ADP. Results: Aspirin non response was found in 14.8% of ischemic stroke patients and 21 % of healthy volunteers, this difference was not statistically significant (p=0.304). No association was found between aspirin non response and age (p=O.863), gender (p=0.992), ethnicity (p=0.965) and - non-obese (p=0.060) among the ischemic stroke patients. Patients with a lower waist circumference were less responsive to aspirin (p=0.047). Conclusion: The prevalence of aspirin non response in patients with ischemic stroke is low and compares well with that documented elsewhere. Therapeutic implication: Therapeutic dose of aspirin is effective in achieving sufficient platelet inhibition in our patients with ischemic stroke. Therefore, the need for aspirin resistance assay should be individualized to the patient.