Comparison of clopidogrel with aspirin versus aspirin alone for the secondary prevention of atherothrombotic events

Background: Dual antiplatelet therapy with clopidogrel plus low dose aspirin has not been studied in broad population of patients at high risk for atherothrombotic events. Method: We randomly assigned 232 patients with either clinically evident cardiovascular and cerebrovascular atherothrombotic events to receive clopidogrel (75mg per day) plus aspirin (75mg per day) or aspirin (75mg per day) and followed them for a period of 12 months. The primary efficacy end point was composite of first occurrence of myocardial infarction (nonfatal), ischemic stroke (nonfatal), death due to cardiovascular/cerebrovascular causes. Results: The rate of primary efficacy end point was 6.19 percent in clopidogrel plus aspirin group and 8.92 percent in aspirin alone group. (Relative risk: 0.69; 95 percent Confidence Interval: 0.27 - 1.75; p = 0.30). The rate of secondary efficacy end point was composite of first occurrence of myocardial infarction (nonfatal), ischemic stroke (nonfatal), hospitalization for angina or transient ischemic attack (TIA) was 15.04 percent in the clopidogrel plus aspirin and 18.75 percent in the aspirin (Relative risk: 0.80; 95 percent Confidence Interval: 0.44 – 1.48; p = 0.28). The rate of bleeding was 6.19 percent in the clopidogrel plus aspirin and 4.46 percent in the aspirin (Relative risk: 1.38; 95 percent confidence interval: 0.45-4.24; p=0.39). The rate of adverse events was 11.50 percent in the clopidogrel plus aspirin and 7.14 percent in aspirin (Relative risk:1.61; 95 percent confidence interval: 0.69-3.73; p=0.18). Conclusion: Clopidogrel plus aspirin was not significantly more effective than aspirin alone for the secondary prevention of atherothrombotic events in patients with myocardial infarction or unstable angina (who have already completed 12 months of dual antiplatelet therapy), stable angina, ischemic stroke or transient ischemic attack.