The analysis reviewed randomised studies of more than 30 days duration comparing the combination of clopidogrel and aspirin with aspirin alone or aspirin and placebo.
The literature search identified 2 studies, CURE and CHARISMA. In CURE it was found that, for every 1,000 patients with acute non-ST segment coronary syndromes treated for 9 months, combination treatment would avoid 23 cardiovascular events at the expense of 10 major bleeds. In CHARISMA is was found that, for every 1,000 patients with a high cardiovascular risk (defined as existing CVD or risk factors for CVD) treated for 28 months, combination treatment would avoid 5 events at the expense of 3 major bleeds.
The authors conclude that the combination should not be used in place of long-term aspirin therapy in patients with established cardiovascular disease or those at high risk for the prevention of cardiovascular disease. They also conclude that in patients with acute non-ST segment coronary syndromes the benefits outweigh the harms and "treatment should be considered".
Action: The addition of clopidogrel to aspirin therapy is not necessary for the majority of patients. The exception is in acute coronary syndromes where the National Institute for Health and Clinical Excellence recommends the combination for a period of 12 months, after which treatment is continued with low-dose aspirin alone.