New risk factors do not improve assessment of coronary heart disease risk
Chicago – Screening for levels of C-reactive protein and other compounds recently found to be associated with coronary heart disease may not help physicians predict risk for the condition with any more accuracy than traditional major risk factors, according to a report in the July 10 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
Major risk factors for coronary heart disease (CHD), which include age, race, sex, blood pressure, diabetes, total and HDL (good) cholesterol levels, smoking status and the use of medications to control blood pressure, predict an individual's probability of developing the condition with reasonable accuracy. Most are also modifiable, so physicians can advise patients on how to change their lifestyle to reduce their risk, according to background information in the article. In recent years, researchers have identified additional risk factors and chemical markers associated with CHD, such as C-reactive protein, a compound in the blood that signifies inflammation caused by injury or infection.
Aaron R. Folsom, M.D., M.P.H., University of Minnesota, Minneapolis, and colleagues with the Atherosclerosis Risk in Communities (ARIC) Study assessed the benefits of screening patients' levels of 19 novel chemical markers, including C-reactive protein, antibodies against infectious diseases, B vitamins and compounds involved in the functioning of blood vessel lining. The ARIC Study enrolled a total of 15,792 adults between the ages of 45 and 74 years in 1987-1989. The participants underwent a physical examination, including assessment of major risk factors, at the beginning of the study and every three years afterward. At four times during the follow-up period, researchers collected blood and DNA samples for analysis. Patients continue to be tracked for the development of CHD.
Several of the compounds tested, including C-reactive protein and vitamin B6, were significantly associated with CHD. The researchers looked at each marker and assessed the probability that a participant who developed CHD within a five-year period had a higher risk score than a participant who did not develop CHD. Using this method, they determined that most of the novel markers did not significantly increase the ability of physicians to predict CHD.
"Although the significant and independent association of a novel risk factor with CHD often does not equate to improved prediction of CHD beyond that of basic risk factors, this does not imply that the novel risk factor is pathophysiologically unimportant or unsuitable as a target for intervention," the authors write. "Based on the totality of evidence, however, C-reactive protein level does not emerge as a clinically useful addition to basic risk factor assessment for identifying patients at risk of a first CHD event."
Routine screening is not warranted for any of the other 18 novel risk factors tested either, the authors conclude. "On the other hand, our findings reinforce the utility of major, modifiable risk factor assessment to identify individuals at risk for CHD for preventive action," they write. (Arch Intern Med. 2006;166:1368-1373. Available pre-embargo to the media at www.jamamedia.org.)
The ARIC Study is a collaborative study supported by contracts from the National Heart, Lung and Blood Institute.
Editorial: Improve Prevention by Focusing on Current Risk Factors
The 19 novel markers studied may someday be useful in assessing risk in certain subpopulations, but for now physicians must focus on improving already recognized risk factors, write Donald M. Lloyd-Jones, M.D., Sc.M., Northwestern University Feinberg School of Medicine, Chicago, and Lu Tian, Sc.D., in an accompanying editorial.
"We need to ensure that the tools we currently have for risk prediction are applied more broadly and routinely throughout clinical practice," they write. "We must also address the enormous gaps between the promise of cardiovascular disease prevention and its reality. We have improved our recognition of those with an elevated blood pressure or cholesterol level, but fewer than one of three Americans with adverse levels of these factors are controlled to goal levels. These issues must be addressed and improved urgently." (Arch Intern Med. 2006;166:1342-1344. Available pre-embargo to the media at www.jamamedia.org.)
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