Heart attack, stroke prevention tool debated
New questions on applying guidelines to people without history of cardiovascular issues
The debate over new heart disease prevention guidelines proposed by U.S. cardiologists is being stirred.
In Tuesday's issue of the medical journal The Lancet, a U.S. doctor and a researcher call the American Heart Association and American College of Cardiology's new guidelines a step forward but point to flaws in applying its risk calculator.
In their commentary, Dr. Paul Ridker and Nancy Cook of the Center for Cardiovascular Disease Prevention at Boston's Brigham and Women's Hospital raised questions about applying the guidelines for primary prevention in people without a history of heart disease, stroke and few risk factors.
Unlike the previous guideline that focused on cholesterol levels, the latest edition uses a risk calculator based on factors such as age and high blood pressure. But estimates from the new calculator were roughly double the actual heart attacks or strokes observed in three major cohort studies, Ridker and Cook said.
"Reliance on the new risk prediction algorithm could put many primary prevention patients on [cholesterol lowering] statin therapy where there is little trial evidence while potentially denying the drug treatment to others where there is evidence," the pair said in the commentary.
A statement posted on the hospital's website said Ridker "strongly supports the key messages of the new guidelines and believes that questions raised about the risk calculator should be relatively easy to address."
The risk calculator precision questions are secondary for Dr. John Abramson of the department of health-care policy at Harvard Medical School in Boston, who likened the calculator issue to rearranging the deck chairs on the Titantic as the ship sank.
Under the new guidelines, people 40 to 75 years old found to have a 7.5 per cent or higher risk of developing heart disease within the next 10 years should be offered statins. While there are clear benefits for using statins in people who've had a heart attack or stroke, that's not the case in primary prevention, Abramson said.
Last month, Abramson, Dr. Jim Wright of the Therapeutics Initiative in Vancouver and their co-authors concluded in the British Medical Journal that 140 low-risk people would have to take statins for five years to prevent a single serious cardiovascular event such as a heart attack. But that serious event is replaced by a significant risk of side-effects that cancels out the benefits, Abramson said Tuesday.
Dr. Kim Williams, vice-president for the American College of Cardiology, said the guidelines are meant to be dynamic and the guideline committee will respond to newer data and suggestions for improvements.
"We're talking about an epidemic of coronary heart disease particularly in the United States but throughout the Western world," Williams told CBC Radio on Monday. "I would still say that this is a step forward because we at least have everyone talking about it and everyone wants to know what is their risk?"
Dr. Donald Lloyd-Jones, a co-chair of the guideline task force, said the 7.5 per cent level is simply meant to start a discussion between doctors and patients about considering statins.
With files from CBC's Kim Brunhuber