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Aspirin Resistance a False Diagnosis for Heart Care

December 05, 2012

There’s no such thing as aspirin resistance, according to a study that suggests a false diagnosis may be unnecessarily raising the number of people given costlier prescription drugs with more side effects to lower their risk of heart attack and stroke.

The report, by University of Pennsylvania researchers, found the coatings put on aspirin by makers such as Bayer AG (BAYN) mask uptake of the medicine in the blood, leading to false diagnoses that it’s not working, said the study published in the journal Circulation. Patients are then put on a prescription blood thinner, such as Bristol-Myers Squibb Co. (BMY:US)’s Plavix.

One in five Americans take a low-dose aspirin tablet daily to reduce heart risks, with most taking coated versions sold as less harsh on the stomach, the university said in a statement. Garret FitzGerald, a lead researcher on the study, said there’s no evidence showing the coatings make aspirin more tolerable.

“The takeaway for consumers is, don’t worry about resistance,” FitzGerald said in a phone interview. “And if you’re taking aspirin, there’s plenty of reason to take the cheap, immediate-release uncoated version.”

Doctors had estimated aspirin may not work for about a third of patients, FitzGerald said.

Not Unexpected

Bayer, which contributed funding for the research, said a delayed uptake of coated aspirin “would not be unexpected,” in an e-mail yesterday. The Leverkusen, Germany-based drugmaker’s statement said the study was flawed because it tested aspirin on a relatively young, healthy population instead of the sick patients who would typically take it to prevent heart problems.

FitzGerald said he didn’t question the effectiveness of coated tablets, but saw no evidence they provided any more value for their price. There’s no reason to suggest sick patients would have a genetic resistance to aspirin while healthy patients wouldn’t, he said.

While the research suggests Bayer’s higher-cost coatings may do more harm than good, it also contained some positives for the company since it found more people may benefit from use of aspirin as a blood thinner than previously thought, said FitzGerald, director of the Institute for Translational Medicine and Therapeutics at the Philadelphia school.

The research also calls into question the value of blood and urine tests sold to diagnose supposed resistance, FitzGerald said. Coated versions of aspirin, meanwhile, may cost 6 cents a tablet compared to less than one cent for bare pills, he said.

“That’s unlikely to be a deal-breaker for most people, but if you look at it from the level of national health spending, and in an era of cost constraints, it starts to add up,” FitzGerald said.

The study gave 400 patients coated and uncoated versions of the medicine and found no consistent pattern of resistance, researchers said in the journal, which is published by the Dallas-based American Heart Association.

Plavix can have side effects including making patients bleed and bruise more easily, New York-based Bristol-Myers says on its website.

To contact the reporter on this story: Alex Nussbaum in New York at

To contact the editor responsible for this story: Reg Gale at

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