Blood tests may help predict stroke
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Testing for high blood levels of two proteins involved in inflammation—Lp-PLA2 and CRP—may help identify people who are at increased risk for stroke, new research suggests.
Ultimately, measuring these proteins could help guide preventative strategies or they may even serve as targets for new drugs, according to the report in the Archives of Internal Medicine.
“Predictors of stroke have received less attention than predictors of coronary heart disease, and often it has simply been assumed that what predicts coronary heart disease also predicts stroke,” lead author Dr. Christie M. Ballantyne, from Baylor College of Medicine in Houston, told Reuters Health. “However, this is not always the case. For example, cholesterol levels have been shown to correlate with coronary heart disease risk, but not with stroke risk.”
Ballantyne said that measuring Lp-PLA2 and CRP levels appears to provide information above and beyond traditional stroke risk factors, such as high blood pressure. “For patients who already have a high or low risk of stroke, measuring these levels may not be particularly useful.” For patients with intermediate risk, however, these tests may help in selecting a preventative strategy.
The findings are based on a study of nearly 13,000 apparently healthy middle-age subjects who were followed for about 6 years to assess the rate of stroke and other outcomes. The study focused on 194 subjects who experienced a stroke and 766 similar subjects who did not.
Stroke patients had significantly higher levels of both Lp-PLA2 and CRP than did comparison subjects. By contrast, and in agreement with previous reports, LDL “bad” cholesterol levels were similar in each group.
Further analysis showed that having high levels of either Lp-PLA2 or CRP nearly doubled the risk of stroke. With high levels of both, the risk of stroke was increased more than 11-fold.
Ballantyne said that his team is planning studies to see if Lp-PLA2 and CRP-based preventative strategies can, in fact, reduce the risk of stroke. Also, he said he is interested in determining if these proteins are not merely markers of stroke risk, but if they are actual mediators of the disease and thus might serve as targets for new drug therapies.
In a related editorial, Dr. Philip Greenland and Dr. Patrick G. O’Malley, from Northwestern University in Chicago, agree that these tests are probably best applied to subjects who have an intermediate stroke risk.
The editorialists comment that “given the relatively modest incremental risk prediction capacity of both CRP and Lp-PLA2 levels beyond traditional risk factors, it would seem inappropriate to recommend either test for routine use. As with coronary heart disease risk assessment, new tests seem most useful when limited to patients initially judged to be at intermediate risk.”
SOURCE: Archives of Internal Medicine, November 28, 2005.
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