Inflammation Markers May Help Predict Stroke Risk
They should be used when assessing traditional risk factors, experts say
THURSDAY, Jan. 8, 2009 (HealthDay News) -- Two molecular signs -- or "biomarkers" -- of inflammation may provide useful information when trying to assess a person's risk of stroke, new research says.
"If you are very high or very low risk, adding these markers does not change things much," said study lead author Dr. Vijay Nambi, a cardiologist at the Methodist DeBakey Heart & Vascular Center and Baylor College of Medicine in Houston. "But if we are not sure if you are at high risk or low risk, they can provide you with more information."
The markers in question are C-reactive protein (CRP) and lipoprotein-associated phospholipase A2 (Lp-PLA2). Both are indicators of inflammation, and both -- especially CRP -- have been well studied as potential predictors of cardiovascular conditions such as heart attack and stroke.
A first assessment of the risk of stroke must start with the well-known risk factors, such as high blood pressure, high cholesterol, obesity, diabetes and lack of physical activity, Nambi said.
In the new report on the long-running Atherosclerosis Risk in Communities (ARIC) study, those risk factors were used to describe 12,762 participants as having a low risk of stroke (less than 2 percent) within the next five years, intermediate risk (2 percent to 5 percent), or high risk (greater than 5 percent) within five years.
Tests for the two biomarkers reclassified 4 percent, 39 percent, and 34 percent of the low-, intermediate- and high-risk categories, respectively.
In all, 4 percent of the individuals were reclassified from the low- to the intermediate-risk group; 10.7 percent and 27.9 percent were reclassified from the intermediate-risk to the high- and low-risk groups, respectively; and 33 percent of the individuals classified as high risk were reclassified to the intermediate-risk group. No individuals were reclassified from the low- to the high-risk group. Reclassification was most frequent in the intermediate-risk group, the study found.
The findings are published in the February issue of the journal Stroke.
The findings don't prove the value of testing for inflammation biomarkers, Nambi said, adding, "They need to be looked at in different populations" of people.
But the study seems to support an American Heart Association recommendation that a CRP test isn't recommended for someone at low risk of stroke, which the association defines as less than 10 percent within 10 years. CPR tests are recommended, however, for individuals at intermediate risk -- 20 percent within 10 years.
And once the classification has been made, the biomarkers aren't the target of preventive measures, Nambi said. The real targets should be lowering blood pressure, keeping blood cholesterol at safe levels, avoiding obesity, and increasing physical activity, he said.
"Blood pressure has a lot more effect on stroke, compared to its role in heart disease," Nambi said. "Cholesterol is of more importance for heart disease."
Dr. Philip Gorelick, director of the Center for Stroke Research at the University of Illinois College of Medicine at Chicago, said "patients who are concerned about the risk of stroke or have risk factors for stroke should have these tests [for inflammation] done."
Adding the two inflammation biomarkers to conventional risk factors "should help determine how aggressively you treat the conventional risk factors, for example, how low you drive down cholesterol levels," he said.
Learn more about CRP's role in heart disease and stroke at the American Heart Association.