Aspirin Resistance

A state in which aspirin fails to exert a beneficial effect on risk factors for heart attack and stroke. Medical experts do not agree whether aspirin resistance is a “real” phenomenon (since some variation in individual response to drugs is normal) or, if it is real, how exactly the term should be defined. Aspirin resistance may be common in people with diabetes.

Over the past several decades, medical researchers have discovered that aspirin, taken daily at low doses, can significantly reduce the risk of heart disease and stroke. Aspirin’s anti-inflammatory effects appear to inhibit the clumping together of blood platelets and the constriction of blood vessels, both of which might otherwise lead to clots in vessels of the brain (causing stroke) or in those leading to the heart (causing heart attack). Aspirin’s inhibitive effects have been confirmed in a number of clinical trials. A meta-analysis that pooled data from over 50,000 individuals in five clinical trials showed that aspirin lowered the risk of coronary heart disease by 28%. In addition, a study called the Primary Prevention Program (PPP) showed that aspirin therapy reduced the risk of cardiovascular disease by over 40% in people with one or more cardiovascular risk factors.

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The American Diabetes Association, the American Heart Association, and the US Preventive Services Task Force recommend aspirin therapy for individuals at high risk for cardiovascular disease, including those with diabetes. (People with Type 2 diabetes are at much greater risk for heart attack and stroke.) However, a report on a subset of people with diabetes from the PPP trial raised some eyebrows in 2003 because it found no significant cardiovascular benefit from aspirin therapy in people with diabetes. The study authors suggested that aspirin resistance might play a role in these people, but they and other researchers have pointed out that the study lacked the “statistical power” to conclusively rule out any benefit. However, a recent meta-analysis of antiplatelet therapy in people with diabetes also found a lack of significant benefit.

The bottom line is that researchers do not yet know whether aspirin has cardiovascular benefits in people with diabetes, and more research needs to be done. In the meantime, medical experts say, the current guidelines for aspirin therapy should remain in place.