SAN FRANCISCO — None of the newer biomarkers being evaluated as possible predictors of cardiovascular risk has been studied enough to be considered ready for clinical use, Michael H. Alderman, M.D., said at the annual meeting of the American Society of Hypertension.
Conventional risk factors such as blood pressure, insulin resistance, diabetes, obesity, lipids, and family history account for 50% of cardiovascular risk, so any biomarkers that could further gauge risk would be useful. A biomarker is a substance that can be measured precisely in serum or urine and is related to subsequent occurrence of cardiovascular disease—such as cholesterol, said Dr. Alderman of Albert Einstein College of Medicine, New York.
A handful of newer, more precise biomarkers appears to be more intimately associated with the development of cardiovascular disease, and they look like they will be useful. These include C-reactive protein, neurocytokines, and uric acid. So far, however, there is “suggestive, but for the most part not yet convincing, evidence that these new biomarkers add to the predictive value already contained in the markers that we have,” Dr. Alderman said at a press briefing during the meeting, where he gave a summary of reports on the newer biomarkers.
To be useful, a new risk marker would have to make a contribution beyond what's obtained from conventional risk markers. “I don't think that's been formally tested” with the newer biomarkers, he said.
Tests for the new risk marker would have to be reproducible at different times and in different populations, and would have to define an important amount, or proportion, of risk, he said. Lastly, an assay for the biomarker would need to be feasible and cost effective when applied to a population.
“Those kinds of questions have been asked of blood pressure screening and cholesterol screening, but haven't been asked of cytokines,” for example, he said.
Dr. Alderman said he believes that uric acid is an independent risk factor for cardiovascular events, particularly in hypertensive patients, but the data supporting this are inconsistent. Other data showing that uric acid is predictive of elevated blood pressure may be more interesting and useful, he said.
“For most of these [new biomarkers], we're not at the point where they're useful, but I think that we're awfully close,” Dr. Alderman said.