Background: Multiple large, randomized, controlled trials and meta-analyses that used aspirin as primary prevention for vascular events showed decreased vascular events, but a significant counterbalanced risk of bleeding. Since diabetes carries a higher risk of vascular events, this study examines aspirin for primary prevention of vascular events in diabetic patients.
Study design: Large, randomized, controlled trial.
Setting: British registry-based study.
Synopsis: This is a 9-year randomized, controlled trial that included 15,480 British patients with diabetes without known vascular disease who were randomized to receive a 100-mg aspirin daily or placebo. Participants in each group were closely matched patients with diabetes who were recruited using registry data and were aged 40 years and older with no alternative strong indication for aspirin.
Overall, aspirin provided no difference in mortality but showed an absolute 1.3% decrease in first vascular events or revascularization procedures with an absolute 1.1% increase in first occurrence of major bleeding event. Approximately 60% of the bleeding events were gastrointestinal or “other” urinary/nose bleeding, and there was no statistically significant increase in intracranial hemorrhage, hemorrhagic stroke, or vision-threatening eye bleeding. Vascular events were defined as transient ischemic attack (TIA), nonfatal MI, nonfatal ischemic stroke, or vascular death excluding intracranial hemorrhage. The major limitation of this study is that it had a composite of endpoints of different clinical significance. Furthermore, TIA as a major vascular event was added after the study began to increase statistical power, and when it is excluded, the difference for vascular events is not statistically significant.
Bottom line: Aspirin when used in primary prevention of vascular events in diabetes provides no improvement in mortality, and the benefit of prevention of vascular events must be weighed against the risks of bleeding.
Citation: The ASCEND Study Collaborative Group. Effects of aspirin for primary prevention in diabetes..
Dr. Scott is an assistant professor in the division of hospital medicine, University of New Mexico.