By Ransdell Pierson and Bill Berkrot
Dallas, Nov 18 (Reuters) - Top cardiologists who devised new U.S. guidelines for reducing risk of heart disease strenuously defended their risk-calculation tool from criticism that it greatly overestimates health risks and the need to be treated with cholesterol lowering statin drugs.
Two Harvard professors, Dr. Paul Ridker and Dr. Nancy Cook, sparked the controversy by saying the risk calculator was flawed in its assessment for some populations and could lead to unnecessary therapy for millions of Americans, according to a report in Monday's New York Times. The report said their criticisms would appear on Tuesday in the British medical journal The Lancet.
Their concerns spurred prominent cardiologist Dr. Steven Nissen of the Cleveland Clinic to call for a delay in putting the new guidelines into practice, the report said. Nissen could not immediately be reached by Reuters.
A half dozen cardiologists who helped formulate the guidelines over a four-year period criticized Ridker's own methodology at a hastily called news conference during the annual scientific sessions of the American Heart Association (AHA) in Dallas.
"We intend to move forward with the implementation of these guidelines," said Dr. Sidney Smith of the University of North Carolina, a past president of the AHA who was executive chairman of the guidelines committee.
"If we think there is something that will make them better, you can count on that we'll do it," Smith said.
The guidelines were created by panels of experts from the AHA and the American College of Cardiology and include a formula for calculating the risk of developing heart disease over 10 years. They only used data from studies undertaken through 2011 and said they would begin updating the guidelines next year to include more recent findings.
The guidelines no longer focus on reducing the level of "bad" LDL cholesterol to specific targets, but instead assess each patient's personal risk factors of developing heart disease. Previous guidelines provided specific LDL targets, such as 100 for most people and 70 for patients at risk of a second heart attack, as the basis for determining who should be taking cholesterol medicines and the appropriate dose to reach targets.
"One out of three Americans will die of heart attack and stroke. These (new) guidelines recommend treating about one third of adults between 40 and 75 with statins for primary prevention, so that sounds about right," said Dr. David Goff, dean of the Colorado School of Public Health and co-chair of the risk-assessment guidelines.
"These guidelines have been vetted by multiple experts many, many times," AHA President Dr. Mariell Jessup said.
The guidelines authors said if more aggressive prevention measures are not undertaken, the cost of cardiac care in the United States could triple to $819 billion by 2030.
Under the new guidelines, people 40 to 75 years old found to have a 7.5 percent or higher risk of developing heart disease within the next 10 years, as assessed by factors plugged into the online calculator, such as being obese or having diabetes, are encouraged to be treated with potent statins, such as Pfizer Inc's Lipitor (atorvastatin), or AstraZeneca's Crestor.
But Dr. Neil Stone, lead author of the cholesterol management guidelines, said the risk percentage number was merely a jumping off point for discussions between physicians and patients about appropriate individual therapy.
"The goal is not to get more people on statins, the goal is to get patients to get older without having a heart attack or stroke," he said.
Authors of the new guidelines on Monday said Ridker based his conclusions of overstated risk on three large population studies that involved subjects who are far healthier than the general population.
The new guidelines were based on more representative populations, the authors said, and consider for the first time the risk of stroke and factor in African-Americans, a group with a disproportionately high risk of heart attacks and stroke.
"We think we came up with a good risk assessment instrument," Smith said.
The guidelines authors said Ridker notified them on Friday of his criticisms for the first time, and that they would appear in the Lancet.
Moreover, several members of the guidelines committee, in interviews, said Ridker reviewed the proposed guidelines in 2012 and did not cite any such concerns.
"We got his review and he did not say anything about these three population studies at that time," Goff said.
Ridker receives royalties as co-holder of patents on a diagnostic test for C Reactive Protein (CRP), a marker for inflammation that could be tied to increased risk for heart disease.
Goff said Ridker, in reviewing the proposed guidelines last year, suggested that CRP testing be included in the risk assessment calculations. But his suggestion was rejected, Goff said.
Dr. Donald Lloyd-Jones, professor of preventive medicine at Northwestern University, said Ridker had not yet provided the guidelines committee with the specific data he used to arrive at his concerns.
"We used what we thought were the best available data" to determine the new guidelines, Lloyd-Jones said. "We'd all like to see Dr. Ridker's data instead of seeing this played out in the media."
Neither Ridker nor Cook could immediately be reached for a comment. However, Ridker, a cardiologist at Brigham and Women's Hospital in Boston, put a statement on the hospital website that was quite positive about the intentions of the new guidelines.
It said that he "strongly supports the key messages of the new guidelines and believes that questions raised about the risk calculator should be relatively easy to address. Dr. Ridker is an advocate of expanded statin use in primary prevention, a major advance of the new ACC/AHA guidelines."
Cook is a biostatistician at Brigham and Women's Hospital and is a professor at Harvard.
Dr. Francisco Lopez-Jimenez, a cardiologist with the Mayo Clinic who was not involved in the guidelines, said he hopes Ridker will provide the guidelines committee his data soon and that AHA and ACC will provide their joint response without delay.
"The main concern is the credibility of the guidelines, regardless if the claims are valid or not," Lopez-Jiminez said.