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STUDY: High levels of CRP corresponded with a 60 to 70 percent increase in stroke risk.
JOURNAL: Circulation 2003;107
AUTHORS: Dr. J. David Curb
ABSTRACT: High levels of a protein linked to inflammation may be a sign of increased risk for stroke in healthy, middle-aged men.
COMMENTARY: In the study, men with the highest blood levels of a protein called C-reactive protein (CRP) were nearly four times more likely than men with the lowest levels to have a stroke a decade or more later.
More research is needed, according to a team led by Dr. J. David Curb at the Pacific Health Research Institute in Honolulu, Hawaii, to see whether measuring CRP levels can identify otherwise healthy people who may have an increased risk of cardiovascular disease.
Other studies have suggested that CRP increases the risk of artery disease, heart attack and stroke. However, researchers have been unsure how the protein is related to the risk of stroke in different age groups and in people with high and low risks of cardiovascular disease.
To investigate, the team of researchers followed about 8,000 Japanese-American men aged 48 to 70 for thromboembolic stroke - a type of stroke that occurs when a clot blocks an artery supplying blood to the brain. All of the men had their CRP levels measured in the late 1960s as part of the Honolulu Heart Program.
After 20 years of follow-up, 259 men had a stroke. This group of men was compared to 1,348 men who participated in the study who did not have a history of heart disease or stroke. Men who had the highest blood levels of CRP at the start of the study were almost four times more likely to have a stroke 10 to 15 years after the study began than men with the lowest levels of the protein, Curb's team reports.
What's more, even among men without diabetes and high blood pressure -- conditions that increase the risk for stroke -- high levels of CRP corresponded with a 60 to 70 percent increase in stroke risk.
Men aged 55 and younger who had the highest levels of CRP had a three-fold increased risk for stroke, and nonsmokers had a nearly six times greater risk of stroke than men with the lowest levels of CRP.
However, CRP levels were not a good indicator of stroke risk in men older than 55, past or current smokers or in men who had high blood pressure or diabetes.
Still, the findings do not rule out that inflammation may play a role in the risk for stroke among individuals who have other risk factors for stroke.