Aspirin therapy not associated with cardiovascular benefit in type 2 diabetes

Aspirin showed no cardiovascular benefit and may have been associated with worse outcomes in a recent study of patients with type 2 diabetes.

Researchers in Sweden performed a population-based cohort study in hospital outpatient clinics and primary care practices to determine the risks and benefits of aspirin therapy in patients who had type 2 diabetes but no previous cardiovascular disease (CVD) at baseline. The study period covered 2005 to 2009, with a mean follow-up of 3.9 years. All included patients were registered in the Swedish National Diabetes Register and received continuous low-dose aspirin treatment or no aspirin treatment. The main outcome measures were risk for CVD, coronary heart disease (CHD), stroke, death and bleeding in patients taking aspirin compared with no aspirin. The study was published on April 20 by BMJ Open.

The aspirin group included 4,608 patients, while the no-aspirin group included 14,038 patients. Approximately 55% of patients in each group were men. Patients ranged in age from 30 to 80 years. The authors found no association between aspirin use and any positive effects on patients' risk for CVD or death but did find an association with increased risk for both nonfatal and fatal CHD (hazard ratio, 1.19; 95% CI, 1.01 to 1.41; P=0.04). When analyzed separately by gender, women taking aspirin had an increased risk for CHD (hazard ratio, 1.41; 95% CI, 1.07 to 1.87; P=0.02) and CVD (hazard ratio, 1.28; 95% CI, 1.01 to 1.61; P=0.04), but the men taking aspirin did not. Aspirin was also associated with a trend toward increased risk for bleeding (hazard ratio, 1.41; 95% CI, 0.99 to 1.99).

The authors noted that residual confounding could not be ruled out and that some patients categorized as without CVD at baseline could in fact have had mild CVD that was not detected. However, they concluded that their results do not suggest any beneficial effects of aspirin in patients with type 2 diabetes but no preexisting CVD and “support the trend towards more restrictive use of aspirin” in this population. They also called for more research into the apparent differences between men and women in this area.