New guidelines for cholesterol management spark controversy; faulty risk calculator could lead to over-prescribing statins

The American College of Cardiology and the American Heart Association released new guidelines for cholesterol management, a new formula to assess heart attack and stroke risk, and guidelines for lifestyle modifications and weight management to reduce heart attack and stroke risk.

?These guidelines will be helpful to all physicians and their patients, but they will be particularly relevant in Kentucky, where nearly 70 percent of Kentuckians are overweight or obese, we are the third highest state in rates of high blood pressure, five Kentucky counties are among the least active in the U.S. and the incidence of diabetes is above the national average,? Dr. Susan Smyth, director of the Gill Heart Institute at the University of Kentucky, said in an e-mail.

However, some experts have questioned the new guidelines, and the new formula for calculating cardiovascular risk appears to overstate the risk value used to determine who should receive cholesterol-lowering statin drugs.

"There may be no single perfect score that we can use to give statins the 'thumbs up' or 'thumbs down' for our patients without established cardiovascular disease," Smyth said. "Ultimately, physicians have many different tools at their disposal to evaluate CV risk in their patients, and they will review all of the available evidence to make a determination about who may be likely to benefit from statin therapy."

The new guidelines also change how statins should be prescribed. The drugs have been given to lower cholesterol to a specific numerical value, but now it is suggested that moderate to high doses of statins be given to patients who fall within four identified groups of patients who have been determined to get the most benefit from the drug:

• already diagnosed with heart disease or stroke
• with an LDL {"bad" cholesterol) of 190 mg/dL or higher, who may have genetic risk
• aged between 40 and 75, with Type 2 diabetes and high LDL levels, but without heart disease or stroke
• with an estimated 10-year risk of cardiovascular disease of 7.5 percent or higher who are between 40 and 75, without heart disease or stroke, but with high LDL levels.  

The guidelines use a cardiovascular risk calculator that considers age, race, sex, diabetes, smoking habits, blood pressure and low HDL, or "good" cholesterol levels, among other considerations.

But a problem has been identified with the risk calculator, so worrisome that a past president of the College of Cardiology called for a halt to the implementation of the new guidelines, reports Gina Kolata of The New York Times. The calculator appears to overestimate the risk group so greatly, Kolata reports, that it could mistakenly suggest that millions more people should be candidates for statin drugs.

"It's stunning," the cardiologist, Dr. Steven Nissen, chief of cardiovascular medicine of the Cleveland Clinic, told Kolata. "We need a pause to further evaluate this approach before it is implemented on a widespread basis."

After an emergency, closed-door meeting on Saturday night, the two organizations that published the guidelines said "that while the calculator was not perfect, it was a major step forward, and that the guidelines already say patients and doctors should discuss treatment options rather than blindly follow a calculator," Kolata reports.

Dr Sidney Smith, the executive chairman of the guideline committee, told Kolata that "the association would examine the flaws found in the calculator and determine if changes were needed."

Two Harvard Medical School professors, Dr. Paul M. Ridker and Dr. Nancy Cook, had pointed out the calculator was not working among the populations it was tested on by the guideline makers a year earlier, during an independent review for the National Institutes of Health's National Heart, Lung, and Blood Institute, which originally developed the guidelines, Kolata reports.

Dr. Donald Lloyd-Jones, co-chairman of the guidelines task force and chairman of the department of preventive medicine at Northwestern University, told Kolata that "the committee thought the researchers had been given these results."

Ridker and Cook evaluated the calculator again after they saw the guidelines and found that it over- predicted risk by 75 to 150 percent, depending on the population, Kolata reports. They wrote in The Lancet, a British medical journal, that the miscalibration be "reconciled and addressed" before implementation, saying: "If real, such systematic overestimation of risk will lead to considerable over-prescription."

Some doctors are concerned that because many people are already "leery of statins, the public would lose its trust in the guidelines or the heart associations," Kolata reports. Currently, it is only obvious that those in the highest risk groups, such as those who have heart attacks, strokes or have diabetes, should take statins, she reports.

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