Contemporary use of dual antiplatelet therapy for preventing cardiovascular events

CHARISMA was a landmark randomized clinical trial that failed to demonstrate a benefit of dual antiplatelet therapy (DAPT) over aspirin alone for preventing cardiovascular events. However, subgroup analyses of the trial found fewer major adverse cardiovascular events (MACEs) for patients with established cardiovascular disease but more MACEs for patients with multiple risk factors without established cardiovascular disease. Our objective was to examine DAPT use in contemporary clinical practice after publication of CHARISMA results.

Retrospective analysis of a large clinical registry of outpatient cardiovascular visits to over 1000 physicians that collected data on patient clinical history, symptoms, vital signs, and medications.

Clinical characteristics and prescription rates of aspirin and clopidogrel were compared for patients with established cardiovascular disease and for patients with only multiple cardiovascular risk factors. Prescription of DAPT by calendar quarter was evaluated from 2008 to 2011 using multivariable Poisson regression models.

Of 167,839 patients with established cardiovascular disease, 20.5% were prescribed both aspirin and clopidogrel. Of 20,478 patients with multiple risk factors but no known cardiovascular disease, 3.5% were prescribed both aspirin and clopidogrel. Across 14 calendar quarters, prescription rates of DAPT did not change significantly for patients with established CVD but decreased for patients with multiple risk factors with an incidence rate ratio of 0.77.

Use of DAPT is modest in patients with established cardiovascular disease, for whom the CHARISMA trial suggested decreased MACEs, and prescription rates have remained stable over time. Use of DAPT in patients with multiple risk factors only, for whom CHARISMA suggested that DAPT may lead to increased MACE, was low and decreased over time.