Researchers including an Indian origin have shed some light on why aspirin benefits some people and not others.

Researchers at Duke Medicine developed a blood-based test of gene activity that has been shown to accurately identify who will respond to the therapy.

The study showed that the new gene expression profile not only measures the effectiveness of aspirin, but also serves as a strong predictor of patients who are at risk for heart attack.

The Duke researchers enlisted three groups of participants - two of healthy volunteers and one comprised of patients with heart disease seen in outpatient cardiology practices.

The healthy volunteers were given a dosage of 325 mg of aspirin daily for up to a month; the heart disease patients had been prescribed a low dose of aspirin as part of their treatment.

Blood was then analyzed for the impact of aspirin on RNA expression and the function of platelets, which are the blood cells involved in clotting.

The RNA microarray profiling after aspirin administration revealed a set of 60 co-expressed genes that the researchers call the "aspirin response signature," which consistently correlated with an insufficient platelet response to aspirin therapy among the healthy subjects as well as the heart disease patients.

The researchers also examined the aspirin response signature in another group of patients who had undergone cardiac catheterizations. They found the signature was also effective in identifying those patients who eventually suffered a heart attack or died.

Deepak Voora, M.D., assistant professor of medicine at Duke and lead author of the study, said that the aspirin response signature can determine who is at risk for heart attack and death.

He said that there is something about the biology of platelets that determines how well we respond to aspirin and we can now capture that with a genomic signature in blood.

The study has been published in the online edition of the Journal of the American College of Cardiology.