Background: Clopidogrel is an antiplatelet medication used in patients with coronary artery disease. A considerable number of patients still experience recurrent ischemic events secondary to thrombosis despite its use. A myriad of factors might contribute to individual responsiveness to clopidogrel. We evaluated the prevalence of clopidogrel resistance among Filipinos and its associated risk factors.
Methods: One hundred eleven (111) patients with documented stable coronary artery disease and who had acute coronary syndrome for more that 6 weeks on a maintenance dose of 75mg clopidogrel for at least two weeks were enrolled. Baseline clinical characteristics were gathered. Whole blood sampling was done to measure platelet function by impedance aggregometry using a point-of-care testing (Multiplatelet® analyzer; Dynabyte Medical, Munich, Germany).
Results: Seventeen (17%) out of 111 patients recruited in the study were classified as low respondents to clopidogrel. The mean age of patients recruited was 60 years old and majority of those recruited were males (n=83, 78%). On multivariate analysis, the use of proton pump inhibitors (PPIs) was associated with statistically significant greater odds of clopidogrel resistance (OR 6.5, 95% CI: 1.96-22.09 p = 0.010). On further analysis of patients taking proton pump inhibitors, we found that only those exposed to omeprazole had a significant association with clopidogrel resistance (OR 9.3, 95% CI: 2.54 t 39.35). No significant correlation was demonstrated in the other clinical parameters observed.
Conclusion: The prevalence of clopidogrel resistance using multiplatelet assay in Filipinos with stable CAD was 15%. Concomitant use of the proton pump inhibitors , specifically omeprazole, significantly increases the odds of clopidogrel resistance by 9.83.