TUESDAY, July 19, 2005 (HealthDay News) -- Measuring total and HDL "good" cholesterol along with a third blood marker, C-reactive protein (CRP), appears to be the best strategy for assessing women's cardiovascular risk, a new study suggests.
The findings, which appear in the July 20 issue of the Journal of the American Medical Association, will likely play an important role in any new screening guidelines, experts say.
"At the end of the day, you can pretty much get where you need to be with total [cholesterol], HDL and CRP," said study author Dr. Paul Ridker, director of the Center for Cardiovascular Disease Prevention at Brigham and Women's Hospital in Boston.
"It's a win-win situation, in that some individuals who are currently estimated to be at moderate risk will be at quite high risk when we measure CRP, so we can do a better job of targeting therapies," Ridker added. On the other hand, he said, "there are probably other patients whose risk isn't as high as we thought, so we can save them the toxicity of the drugs."
While cholesterol levels have long been key in predicting cardiovascular risk, the search for new, reliable measurements has continued because experts say half of all heart attacks and strokes occur in individuals with normal cholesterol levels.
Ridker first discovered CRP, a marker of inflammation, about a decade ago. While CRP is not currently part of the regular panel of tests, 25 major studies now suggest that CRP levels predict future cardiovascular events in both men and women.
"This high-sensitivity CRP has been getting a lot of positive feedback, showing that it actually can add some information, especially in intermediate risk, and may be important to follow," said Dr. Mary Ann McLaughlin, an assistant professor of medicine at Mount Sinai School of Medicine in New York City.
At the same time, Ridker pointed out, doctors are under increasing pressure to use more expensive tests, focused on blood compounds such as apolipoprotein A-I and B100.
There has been little data to support using these tests, however.
For this study, Ridker and his colleagues followed 15,632 initially healthy women, aged 45 and older, for a decade. All of the women were enrolled in the ongoing Women's Health Study.
Ridker's team measured blood levels of total cholesterol, LDL ("bad") cholesterol, HDL ("good') cholesterol, non-HDL cholesterol, the apolipoproteins A-1 and B100, high-sensitivity CRP and several ratios of these measurements.
Women with the highest levels of total cholesterol faced twice the risk of future heart disease, the researchers report, while those with the highest levels of non-HDL cholesterol were at a 2.5-times increased risk. Even more impressive was the finding that women with the highest blood levels of CRP faced triple the risk of cardiovascular events such as heart attack or stroke.
"Perhaps of equal importance, these all measure different facets of risk and thus are 'additive' to each other," Ridker said. "Also important is that these risks are adjusted for age, smoking, blood pressure, diabetes and obesity and thus are fully independent of 'traditional' risk factors for heart disease."
All of this means that standard lipid measures -- namely, the ratio of total cholesterol to HDL cholesterol -- rather than more complex measures such as apolipoproteins A-1 and B100, should be the physician's primary method of evaluating cardiovascular risk, the researchers concluded.
"They're saying that adding these extra tests did not give them any more information," McLaughlin said. "The bottom line is that we can still use the good old ratio of total to HDL, or the non-HDL cholesterol, as predictors of cardiovascular risk and that should be good enough."
And CRP was icing on the cake. "CRP adds a lot of information on risk," Ridker said.
"There's a great debate going on right now whether to add CRP to the guidelines, whether the [previous] decision to go with non-HDL cholesterol was a good one and whether or not expensive lipid measures are required," Ridker added. "This paper will be very influential for thinking about these issues."
The American Heart Association has more on CRP.