ORLANDO, FLA. -- A noninvasive point-of-care test that measures cholesterol in the skin is useful in identifying subclinical atherosclerosis in asymptomatic middle-aged adults, James H. Stein, M.D., reported at the annual meeting of the American College of Cardiology.
The PREVU Point of Care Skin Sterol Test, which recently became commercially available, may enable some patients deemed at intermediate cardiovascular risk on the basis of conventional risk factors to be spared the inconvenience and expense of referral for follow-up noninvasive or invasive testing aimed at further defining their risk, according to Dr. Stein, codirector of the preventive cardiology program and director of the vascular health screening program at the University of Wisconsin, Madison.
"Because skin sterol is easy to measure, it may be a useful office-based tool for cardiovascular risk prediction. And in my opinion, we need to bring cardiovascular risk prediction back into the office, where the doctor and the patient interact.... What excites me about this test is, it at least holds out the potential that within 3-5 minutes, we can have an answer for the patient--or at least a little bit of guidance that helps push the patient and physician in the right direction," he said.
Dr. Stein reported on 81 consecutive asymptomatic patients with cardiovascular risk factors but without known vascular disease who were referred by their primary care physicians to the University of Wisconsin for B-mode ultrasound determination of their carotid artery intima-media thickness, a well-validated marker for subclinical atherosclerosis. The subjects' mean age was 56 years. Their average 10-year predicted risk of a cardiovascular event using the Framingham risk score was 7%, although that's clearly an underestimate, because 40% of participants in this study were already on lipid-lowering therapy.
Skin-tissue cholesterol level proved to be significantly and independently correlated with carotid intima-media thickness. The mean skin-tissue cholesterol value was 95.9 units. After controlling for standard cardiovascular risk factors including age, gender, systolic blood pressure, blood glucose, and the ratio of total to HDL cholesterol, each 10-unit increase in skin cholesterol was associated with a 59% increase in carotid intimamedia thickness.
Skin cholesterol as measured by the PREVU test had previously proved to be associated with the presence and extent of coronary artery disease in patients with angina or a positive exercise stress test. The new study presented by Dr. Stein is the first to look at the skin test's utility in the setting where physicians find the need is greatest: as a simple, noninvasive means of improving risk prediction in patients with cardiovascular risk factors but not manifest CAD.
The PREVU test doesn't require a blood draw, pretest fasting, or a skin biopsy. The test measures cholesterol level colorimetrically in the skin of the patient's palm. The rationale for using the test as a marker for subclinical atherosclerosis is that as cholesterol accumulates in artery walls it also concentrates in other tissues--including the skin.
"I want to emphasize that the skin cholesterol test is really not meant in any way to replace traditional risk-factor assessment, including traditional cholesterol testing, or even some of the newer markers that are available. I think all these tests are complementary," the cardiologist said.
"What we're looking at here," he explained, "is an anatomic measure of the atherosclerotic disease process itself, rather than yet another marker that's associated with atherosclerosis. It's important not to think of the skin cholesterol test as a different way of measuring blood cholesterol; they're really two separate processes."
The study was funded by IMI International Medical Innovations, Inc., which developed the PREVU test, marketed by McNeil Consumer Healthcare.
BY BRUCE JANCIN
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