DALLAS - Aug. 2, 2005 - A protein in the blood that isconsidered to be a key indicator of future heart disease may varyconsiderably among women and men, as well as blacks and whites,according to new research at UT Southwestern Medical Center.
C-reactiveprotein, or CRP, is released as part of the human body's inflammationresponse. Infections and inflammation caused by various illnesses cancause CRP levels in the blood to rise. Abnormal fatty deposits on theinterior walls of arteries that are prone to rupture and cause heartattacks may also cause higher levels of CRP, which is why the proteinhas been touted recently as a means to determine the relative risk ofheart disease in some patients.
Current recommendations for CRPtesting use the same cut points to determine risk for everyone. But onesize may not fit all, and there may be important differences betweengenders and races. A study by UT Southwestern researchers, appearing inthe Journal of the American College of Cardiology, examines thesedifferences.
"Our goal was to determine the distribution of CRPlevels among different genders and races," said Dr. Amit Khera,assistant professor of internal medicine and lead author of the study."CRP as a risk factor for cardiovascular disease has been studiedmainly in white men and in research groups that do not necessarilyrepresent the community at large. The recommended thresholds of CRP maynot appropriately reflect CRP distributions for black men and women."
Researchersmeasured CRP levels in 2,749 men and women ages 30 to 65. They foundthat patients with a higher body mass index, a measurement of obesity,had correspondingly higher levels of CRP. The study also found thatwomen typically had much higher levels of CRP in their blood than men,and blacks had higher levels of CRP than white patients. CRP levels inwhite women were also higher than those in black men. Black men,however, have disproportionately higher rates of cardiovascular diseasethan white women.
"Our study was a snapshot of a population, butit showed that white women have higher levels of CRP than both blackand white men. Since white women have lower rates of cardiovasculardisease, this study raises some questions about how best to use CRP inthe real-world setting." said Dr. Khera. "We need more research todetermine if these differences translate into differences incardiovascular events."
Dr. Khera added it's possible thatdifferent thresholds would need to exist between men and women to moreaccurately determine the risk of heart disease. It may also be thatreliance on CRP for risk assessment in black patients may overestimatethe risk for cardiac and vascular events, as more than one-half ofthese patients had elevated levels. But there are currently few studiesof CRP in black patients.
Dr. James de Lemos, assistant professorof internal medicine and the study's senior author, said: "This is alarge study that highlights potentially important race and genderdifferences in CRP levels. The most striking finding was theobservation that almost two-thirds of black women had CRP levels abovethe Centers for Disease Control-defined high-risk threshold. Thesedifferences may have implications for the broad use of CRP testing."
Long-termstudies are needed to see if increased CRP levels in the blood lead toheart disease in a large and diverse population. If so, it may becomenecessary to adjust CRP levels according to race and gender, Dr. deLemos said.
This research is part of the Dallas Heart Study - amultiethnic, population-based study of more than 6,000 patients inDallas County designed to examine cardiovascular disease. The DallasHeart Study is funded by the Donald W. Reynolds Foundation.
OtherUT Southwestern researchers involved in the CRP study included: Drs.Darren McGuire, assistant professor of internal medicine; Sandeep Das,postdoctoral fellow; Wanpen Vongpatanasin, associate professor ofinternal medicine; Frank Wians, professor of pathology; and ScottGrundy, professor of internal medicine and director of the Center forHuman Nutrition. Researchers from Brigham and Women's Hospital, Boston,also contributed.
The C-reactive protein measurement study was supported by a grant from Roche Diagnostics.
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