Aspirin use in patients with diabetes requires careful consideration

American College of Cardiology 60th Annual Scientific Sessions

NEW ORLEANS — Aspirin has been proven to be effective in reducing the risk for cardiovascular events; however, patients with diabetes are a unique population that requires special considerations before treatment. While aspirin therapy is recommended, further exploration into dosing strategies, stronger antiplatelet therapy and the clinical interaction between aspirin and patients with diabetes is essential, a speaker said here.

“A landmark study published in 1990 really set the stage as to why diabetics are different and why antiplatelet therapy may be effective in this population,” Jeffrey S. Berger, MD, of the NYU Cardiac and Vascular Institute at the NYU Langone Medical Center in New York, said during a presentation. “Compared with nondiabetics, diabetics had greater platelet activity.”

Berger noted that one study currently being conducted at NYU suggests that markers of platelet activity correspond well with an increasing prevalence of diabetes, even in patients without CV disease. Data from other trials support this association, and these results raised an important question: Can measuring platelet activity prevent a future event? At present, this question remains unanswered but warrants further investigation, he said.

A closer look

In addition, physicians must consider dosing when treating with aspirin. Berger explained that aspirin inhibits COX-1 and, thus, reduces amounts of platelet activation and vascular constriction. However, aspirin at higher doses also reportedly inhibits prostacyclin, which causes an effect opposite of thromboxane. Therefore, Berger emphasized that physicians be careful not to prescribe too much aspirin, even among patients with diabetes.

Many physicians believe that patients with diabetes have a different clinical response to aspirin than those without the disease. Berger pointed out that this is a misconception, however, and cited data from a large meta-analysis that indicated no significant differences in aspirin's effect on decreasing myocardial infarctions, stroke or all-cause mortality in patients with diabetes compared with those without the disease. Most importantly, he said, research showed no significant interaction in how aspirin prevents CV events between patients with diabetes and those without.

Despite aspirin’s efficacy in decreasing CV benefits, the medication has been linked with serious adverse events, such as major bleeding, with research showing a low number needed to treat and a low number needed to harm.

“Thinking about it this way, for every 1,000 patients treated for 5 years, three ischemic events are avoided, but three major bleeds are caused,” Berger said. “So when you’re thinking about who should get aspirin, you should think about the absolute benefit and the absolute risk.”

Future studies

Because patients with diabetes are a special population, researchers and physicians should consider whether stronger antiplatelet therapies are required. Berger said future studies must take other medications into account. Statins, fish oil and ACE inhibitors, for example, have antiplatelet activity and this effect may attenuate some of aspirin's effect. He also noted that dosing strategies may have to be altered, such as administering aspirin twice a day instead of once daily. Additionally, improved tools for monitoring aspirin’s effect on preventing CV events would also be extremely valuable, according to Berger.

“There is no significant clinical interaction between diabetics and nondiabetics regarding the effect of aspirin. It remains uncertain if diabetics may need a different strategy of dosing or a stronger antiplatelet therapy, and I think future clinical trials should address these issues,” Berger said. – by Melissa Foster

Disclosure: Dr. Berger reports receiving fees from Astra Zeneca.

For more information:

• Berger JS. ACC Symposium 0622-7. Presented at: ACC 60th Annual Scientific Sessions; April 2-5, 2011; New Orleans.

Dr. Berger raised some very provocative points, particularly about what dose of aspirin should be used. The fact that he showed data that suggest that a lower dose of 81 mg may not be as effective as we think in patients with diabetes is an important take-home message. I don’t think that message is really out there. The other very provocative point he raised is that we need better tools to monitor the effect of aspirin like we have to monitor the effect of cholesterol-lowering and blood pressure-lowering drugs. We are really missing that with aspirin. Some of the focus for future trials that he discussed would be incredibly useful to the overall care for the patient with diabetes.

– Rhonda Cooper-DeHoff, PharmD

Associate Professor, Department of Pharmacotherapy and Translational Research
Colleges of Pharmacy and Medicine, University of Florida

Disclosure: Dr. Cooper-DeHoff reports no relevant financial disclosures.

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