NEW YORK (Reuters Health) – For now at least, the U.S. Preventive Services Task Force (USPSTF) does not recommend that nontraditional risk factors for coronary heart disease be used for patient assessment due to a lack of evidence to support their utility in individuals at intermediate risk.

Current USPSTF guidelines recommend using the Framingham risk score to identify persons at high risk (10-year risk > 20% for a major coronary heart disease event).

To assist the USPSTF in evaluating the benefit of adding novel risk factors to the Framingham risk score, Dr. Mark Helfand from the Oregon Health & Science University in Portland and his associates summarized results of nine systematic reviews of novel risk factors. Their results are published in the Annals of Internal Medicine for October 6.

In addition, based on the researchers’ report, the USPSTF has issued a Recommendation Statement, which appears in the same issue of the journal.

The nine risk factors — C-reactive protein, coronary artery calcium score measured by electron-beam computed tomography, lipoprotein(a), homocysteine level, leukocyte count, fasting blood glucose, periodontal disease, ankle-brachial index, and carotid intima-media thickness – were each assessed with 5 criteria:

–It should be easily and reliably measured. –It should independently predict major coronary heart disease events in intermediate-risk patients with no history of coronary artery, cerebrovascular, or peripheral vascular disease. –A substantial proportion of people at intermediate risk based on their Framingham risk score should be reclassified as high risk. –The reclassification should alter patient management. –If 2 or more risk factors provide similar prognostic information, convenience, availability, cost and safety should be considered when choosing from among them.

None of the other risk factors satisfied all the criteria. Most had not been evaluated for their usefulness in reclassifying intermediate-risk individuals, the researchers found.

Of all nine factors, C-reactive protein “was the best candidate for use in screening and the most rigorously studied,” the authors said, but even for this marker there was no conclusive evidence that monitoring of changes could lead to primary prevention of coronary heart disease events.

There is “no evidence that risk stratification with any of these risk factors, either independently or in addition to Framingham risk scoring, reduces myocardial infarction or cardiovascular disease mortality compared with risk stratification and treatment on the basis of Framingham scoring alone,” the USPSTF said in its Recommendation Statement.

The USPSTF also notes that the dangers inherent in assessing nontraditional risk factors have not been studied. For example electron-beam computed tomography uses the same amount of radiation as 10 chest x-rays. Also, false-positive test results could lead to unnecessary invasive procedures and side effects of aggressive risk factor management.

The Recommendation Statement concludes: “The current evidence is insufficient to assess the balance of benefits and harms of using the nontraditional risk factors studied to screen asymptomatic men and women with no history of coronary heart disease to prevent coronary heart disease events.”

Reference:
Ann Intern Med 2009;151:474-482,496-507.