The Dangers of Aspirin Resistance

A common blood-thinning treatment, often very effective in preventing blood clots and cardiovascular (CV) events (such as hearth attack and stroke), is the simple daily consumption of aspirin. A recent study has shown that those resistant to aspirin are much more likely to experience blood clots or CV events than those patients who are properly effected by aspirin consumption (aspirin “sensitive” patients).

The study considered 2,930 patients with cardiovascular disease (CVD), who were prescribed a standard level of daily aspirin consumption (75-325 mg) as part of their treatment. Aspirin “resistance,” which is determined through platelet response analysis, was observed in 810 (28%) of the patients. Aspirin resistance was also shown in the study to be more prevalent in women than in men.

Across all backgrounds, including age, sex, and presence of other conditions (such as diabetes, smoking and hypertension), aspirin resistance was shown to greatly increase the risk of a CV event. Overall, 39% of those resistant to aspirin experienced CV events, while only 16% of other patients suffered CV events. Other blood-thinning medications and treatments (such as concomitant therapy with clopidogrel or tirofiban) also were ineffective for aspirin-resistant patients.

A major issue in medical research and patient diagnostics has been the reality of the existence of aspirin resistance, and if it does exist, how to test for it before potentially unnecessary administration.

This study does not provide a method for determining resistance, but it does fairly definitively verify its existence, and the necessity for finding a universal test for it. Aspirin is very effective for those “sensitive” to it, but for those resistant, other treatments must be pursued in order to avoid CV events and potential death.

Source: Defeat Diabetes Foundation: Krasopoulos, George. Brister, Stephanie. Beattie, Scott. Buchanan, Michael. British Medical Journal. “Aspirin “resistance” and risk of cardiovascular morbidity: systematic review and meta-analysis.” January 2008.