TUESDAY, Sept. 28, 2010 (HealthDay News) -- Levels of the blood biomarker C-reactive protein (CRP) can vary among different racial and ethnic groups, which might be a key in determining heart-disease risk and the value of cholesterol-lowering drugs, a new British study suggests.
CRP is a sign of inflammation, and elevated levels have been linked -- but not proven -- to an increased risk for heart disease. Cholesterol-lowering drugs called statins can reduce heart risk and CRP, but it's not clear if lowering levels of CRP helps to reduce heart-disease risk.
"The difference in CRP between populations was sufficiently large as to influence how many people from different populations would be considered at high risk of heart attack based on an isolated CRP measurement and would also affect the proportion of people eligible for statin treatment," said study researcher Aroon D. Hingorani, a professor of genetic epidemiology and British Heart Foundation Senior Research Fellow at University College London.
"The results of the current study indicate they [physicians] should bear ethnicity in mind in interpreting the CRP value," she added.
The report is published in the Sept. 28 online edition of Circulation: Cardiovascular Genetics.
For the study, Hingorani and her colleagues reviewed 89 studies that included more than 221,000 people. They found that CRP levels differed by race and ethnicity, with blacks having the highest levels at an average of 2.6 milligrams per liter (mg/L) of blood. Hispanics were next (2.51 mg/L), followed by South Asians (2.34 mg/L), whites (2.03 mg/L), and East Asians (1.01 mg/L).
The U.S. Food and Drug Administration recently approved using one statin, rosuvastatin (Crestor), to prevent heart disease in men over 50 and women over 60 who have at least one risk factor for heart disease and CRP greater than 2 mg/L, Hingorani's group noted.
Using that criteria, more than half of blacks and Hispanics would probably have CRP levels of 2 mg/L at 50 years of age, while fewer than half of East Asians would have that CRP level at age 50, the study authors said.
At age 60, less than 40 percent of East Asians, but almost two-thirds of blacks and Hispanics would probably have a CRP level higher than 2mg/L, the researchers said.
"The differences in CRP between populations may be partly genetically determined, and partly [explained] by differences in diet, lifestyle and other heart attack risk factors," Hingorani said. "However, most of the difference in CRP between populations is currently unexplained," she added.
The American Heart Association says "CRP may be used at the discretion of the physician as part of a global coronary risk assessment in adults without known cardiovascular disease." A CRP value above 3 mg/L is considered high risk for heart disease, according to the association.
Dr. Gregg Fonarow, an American Heart Association spokesman and cardiology professor at the University of California, Los Angeles, noted that CRP has been "increasing utilized as a component of cardiovascular risk prediction and to identify among intermediate risk patients the ones that may benefit the most from statin therapy for primary prevention."
"This study highlights that further studies are needed to develop and validate cardiovascular risk prediction tools for all the major ethnic groups, so that effective primary prevention therapies can be optimally targeted to those who will benefit the most," he added.
To learn more about C-reactive protein, visit the American Heart Association.