Aspirin not effective for primary prevention in diabetes
The large randomised controlled ASCEND trial (n=15,480) shows that aspirin reduced the risk of serious vascular events in people with diabetes and no CVD by 12% but also increased the risk of major bleeding by 29% and the authors concluded that absolute benefits were outweighed by bleeding hazard. The trial suggests that aspirin should not be used for primary prevention in patients with diabetes.
The ASCEND trial was a 2x2 factorial trial that included patients 40 and older with diabetes and no evidence CVD at baseline. Patients were randomized both to enteric-coated aspirin 100 mg daily or placebo and to supplementation with 1-gram capsules of omega-3 fatty acids or placebo. Most (94%) of the patients had type 2 diabetes.
Patients were followed up for an average of 7.4 years and although serious vascular events occurred in a significantly lower percentage of participants in the aspirin group, they also experienced an increase in major bleeding events with most of the increase being gastrointestinal and other extracranial bleeding.
In addition, the use of low-dose aspirin did not result in a lower risk of gastrointestinal tract cancer or other cancer over the mean follow-up of 7.4 years, but further follow-up is needed to assess any longer-term effects on cancer reliably.
Key findings from the ASCEND trial
This study suggests that there may be no use for aspirin in primary prevention in patients with diabetes. These findings may have more impact in the USA where recent guidelines (AHA and AHA/ADA) have suggested that use of low-dose aspirin is reasonable in certain patients with diabetes depending on 10-year CVD risk and bleeding risk. In contrast, the 2016 European guidelines on CVD prevention already contain a class III recommendation against using antiplatelet therapy (including aspirin) in people with diabetes who do not have CVD.
The ASCEND Study Collaborative Group. Effects of aspirin for primary prevention in persons with diabetes mellitus. New Engl J Med 2018; DOI: 10.1056/NEJMoa1804988 https://www.nejm.org/doi/full/10.1056/NEJMoa1804988