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Dual Antiplatelet Therapy Acetylsalicylic Acid Dosing: A Review of the Clinical Effectiveness and Harms

Last updated: March 14, 2017
Project Number: RC0875-000 - RD0037-000
Product Line: Rapid Response
Research Type: Drug
Report Type: Summary with Critical Appraisal
Result type: Report


  1. What is the comparative clinical benefit and harm of different doses of acetylsalicylic acid as part of dual antiplatelet therapy following percutaneous coronary intervention?

Key Message

A limited quantity of evidence was identified on aspirin doses as part of dual antiplatelet therapy however one large, well-conducted randomized controlled trial included in this report directly addressed this research question. This international trial reported no differences in the outcomes of cardiovascular death, myocardial infarction, stroke, stent thrombosis, or major bleeding outcomes between high-dose (300 325 mg per day) and low-dose (75 100 mg per day) aspirin in dual antiplatelet therapy regimens with clopidogrel. During the three-month follow-up, evidence of a statistically significant increase in recurrent ischemia was reported for patients receiving the low aspirin dose as part of the dual antiplatelet therapy regimens. A retrospective observational study also did not observe statistically significant differences for dual antiplatelet therapy patients in cardiovascular death, myocardial infarction, stroke or major bleeding outcomes between high-dose (325 mg per day) and low-dose (81 mg per day) aspirin. Both studies observed a significant increase in minor bleeding outcomes for patients in this population receiving the high-dose aspirin regimens following percutaneous coronary intervention management. A third study, with important methodological limitations, was consistent with the large randomized controlled trial and did not observe a statistically significant difference in the occurrence of stent thrombosis between patients receiving a moderate/high-dose (162 325 mg per day) or a low-dose (81 mg per day) aspirin as part of a dual antiplatelet therapy regimen. The evidence presented in this report was therefore consistent in that low-dose aspirin as part of dual antiplatelet therapy did not increase incidence of cardiovascular death, myocardial infarction, stroke, or stent thrombosis however higher-dose aspirin increased the frequency of bleeding complications without any clear benefit.