The test is the highly sensitive C-reactive protein (hs-CRP) test. CRP is an inflammatory marker found in the blood. Several studies have demonstrated that increased concentrations of CRP appear to be associated with increased risk for coronary heart disease, sudden death and peripheral arterial disease.
Thomas A. Pearson, M.D., Ph.D., co-chair of the AHA/CDC writing group that crafted the new recommendations, says there is "no need for hs-CRP screening of the entire adult population as a public-health measure."
George A. Mensah, M.D., co-chair of the writing group and chief of the cardiovascular health program at the CDC, explains: "For clinicians and public health practitioners, it is important to emphasize that although abnormal hs-CRP values identify high risk persons, we have no evidence that treatment strategies based on hs-CRP levels improve survival or reduce cardiovascular complications.
"Although our statement identifies a subgroup of patients who may benefit from hs-CRP testing, for most patients the emphasis must remain on detection, treatment, and control of the major risk factors, such as high blood pressure, high blood cholesterol, cigarette smoking and diabetes," adds Mensah.
Therefore, the writing group doesn't consider the new test in the same category as cholesterol testing or high blood pressure screening. However, Pearson says the test might be useful when a physician is undecided about a course of treatment for a patient who is considered intermediate risk.
For example, a person at intermediate risk may be someone considered to have a 10 percent to 20 percent risk for heart attack in the next 10 years based on his or her current health status and history. "In those cases, an hs-CRP test might tip the scale to help a physician decide on moderate or more intensive treatment," he says.
Pearson explains that hs-CRP has been so widely publicized that many Americans are asking to be tested, while health professionals have been given no formal recommendations about testing. For example, he says that tens of thousands of hs-CRP blood tests were obtained in the past two years, even though very little scientific evidence supported their widespread use.
The AHA/CDC group reports that the results of hs-CRP tests should be expressed as milligrams per Liter (mg/L) with concentrations of less than 1.0 mg/L defined as low risk, 1.0-3.0 mg/L as average risk and concentrations higher than 3.0 mg/L defined as high risk. People in the high-risk group have about a two-fold increase in relative risk for cardiovascular disease compared to those in the low-risk group.
Pearson says the new recommendations set down these evidence-based parameters for using hs-CRP:
Both Pearson and Mensah emphasize that the new recommendations are based on current evidence, and may need to be changed as new clinical trial results become available.
Pearson, who is senior associate dean for clinical research at the University of Rochester School of Medicine and Dentistry, Rochester, New York, says the AHA/CDC group analyzed all available data using the U.S. Surgeon General's criteria for inference of causality and the American College of Cardiology/American Heart Association classification of recommendations and levels of evidence.
Other writing group members were R. Wayne Alexander, M.D., Ph.D.; Jeffrey L. Anderson, M.D.; Richard O. Cannon III, M.D.; Michael Criqui, M.D.; Yazid Y. Fadl, M.D.; Stephen P. Fortmann, M.D.; Yuling Hong, M.D., Ph.D.; Gary L. Myers, Ph.D.; Nader Rifai, Ph.D.; Sidney C. Smith Jr., M.D.; Kathryn Taubert, Ph.D.; Russell P. Tracy, Ph.D.; and Frank Vinicor, M.D.
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