Easy Blood Test May Reveal Women's Heart Risk
White Blood Cell Count May Work When Other Tests for Heart Disease Fail
WebMD News Archive
March 14, 2005 - A woman's white blood cell count may not only be a sign of how healthy her immune system is, but it may also reveal her risk of heart disease when other tests fail, a new study suggests.
Researchers found that women with the highest white blood cell counts had twice the risk of dying of heart disease than those with the lowest levels, even after adjusting for other known risk factors such as high cholesterol, smoking, diabetes, being overweight, or high blood pressure.
White blood cells are cells that help the body fight infection and other diseases. The immune system typically releases more white blood cells in response to infection.
The results lend support to a growing body of evidence that suggests infection and the resulting inflammation it causes within the body play a critical role in heart disease and hardening of the arteries.
If further studies confirm this association between white blood cell count and heart disease risk, researchers say this inexpensive and widely available blood test may spot those at risk for a heart attack or stroke who are not identified by other risk factors.
White Blood Cells May Indicate Heart Health
In the study, which appears in the March 14 edition of Archives of Internal Medicine, researchers looked at data collected from more than 70,000 postmenopausal women who participated in the Women's Health Initiative Observational Study. All of the women were free of heart disease at the start of the study and were followed for an average of about six years.
The women's white blood cell counts were also measured at the start of the study, and researchers divided the women into four levels according to their initial white blood cell counts.
The results showed that women in the top fourth with the highest white blood cell counts were twice as likely to die of heart disease during the study period than those in the lowest fourth, after adjusting for other risk factors.
In addition, women in the top fourth also had a 40% higher risk of nonfatal heart attack, 46% higher risk of stroke, and 50% higher risk of death due to any cause.
Researchers say the predictive power of women's white blood cell count was about as strong as another heart disease risk factor associated with inflammation, C-reactive protein (CRP).
"These data add to available evidence in men suggesting a similar link and suggest that the predictive role of WBC [white blood cell] count is independent of CRP," write researcher Karen Margolis, MD, MPH, of the Hennepin County Medical Center in Minneapolis, and colleagues.
Researchers say categorizing people's heart disease risk according to inflammatory markers, including the white blood cell count, may identify people at high risk of heart disease who are not identified by traditional risk factors.
In an editorial that accompanies the study, Mary Cushman, MD, of the University of Vermont, says the cost of tests that measure white blood cell counts are much lower than other new heart disease risk tests currently under consideration.
"It is reassuring to see continuing study of simple and well-standardized biomarkers," writes Cushman. But she says whether novel risk markers such as white blood cell count or CRP concentration should be added to routine heart disease screening in people without symptoms of heart disease is an area "of ongoing intense interest" and will require more study.