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Blood tests may help predict stroke
Last Updated: 2005-11-28 16:00:25 -0400 (Reuters Health)
By Anthony J. Brown, MD
NEW YORK (Reuters Health) - 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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