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This study tested the capability of an assay to predict aspirin response and reduce ischemic events, and healthcare costs, and delays to optimal treatment. Patients who needed aspirin in the course of normal medical care were included. Patients were excluded if they had disorders affecting platelet function, alcohol use within 24 hours of a test, or NSAID use. Dose escalation of chewable aspirin from 81 mg, to 162 mg, to 325 mg daily occurred based on the results of whole blood impedance aggregation testing to the agonists, collagen (1ug/mL, 5 ug/mL) and arachidonate (0.5 mM) after 10-14 days of treatment. The experimental in vitro test was conducted in triplicate by performing aggregometry on samples spiked to a concentration of 10 uM of aspirin in 0.05% dimethyl sulfoxide. Of the 36 patients who were compliant 16 were found to be resistant to the antiplatelet effects of 81 mg daily aspirin. Nine of these patients were predicted to stay resistant despite dose increase. Once tested at higher doses, ten remained resistant. Seven of the 16 patients were predicted to become sensitive to a higher dose while six actually did. Predicted response to increased doses of aspirin was in good agreement with actual response. Sensitivity of the assay was 83% and specificity was 80%. Results are promising and indicate that it is possible to predict, with reasonable accuracy, if a patient will have an adequate platelet response to aspirin or if the patient will never respond to aspirin necessitating an alternative antiplatelet regimen. Larger, multisite studies are inevitably needed., (© 2018, The American College of Clinical Pharmacology.)

Introduction: Aspirin and clopidogrel are mainstays in secondary stroke prevention; however, some patients do not demonstrate optimal antiplatelet effects from these therapies. Objectives: The primary objective of this study was to determine if pharmacist medication intervention paired with anti‐platelet medication monitoring with whole blood aggregometry improved responsiveness to antiplatelet treatment when compared with standard‐of‐care, alone in patients at risk of recurrent stroke or transient ischemic attack (TIA). Methods: This retrospective chart review at an outpatient neurology practice examined patients treated post‐stroke or post‐TIA between 2005 and 2017. Patients were categorized as either having undergone platelet function testing (PFT) with pharmacist intervention and standard‐of‐care or standard‐of‐care alone. Patient populations for each group were matched based on age, sex, and ABCD2 risk scores. Pharmacotherapeutic management and interventions were assessed in each group. Results: A total of 342 patients were included as two matched groups (n = 171 for each group) with parallel baseline characteristics. Drug‐drug interactions were identified (P <.0001), and counseling on adherence (P =.0008) occurred statistically significantly more often with a pharmacist involved in patient care. After pharmacist intervention and PFT, 83% of patients were considered responsive to their antiplatelet therapy compared with 27% at baseline in the pharmacist intervention group (P <.0001). Conclusion: Pharmacist interventions optimized secondary stroke/TIA prophylaxis therapy, decreased drug‐drug interactions, and increased adherence counseling. Patients who underwent PFT and pharmacist intervention transitioned from nonresponsive to responsive to their antiplatelet therapy regimen. [ABSTRACT FROM AUTHOR]