Heart study underlines blood cell count

A high white blood cell count may predict cardiovascular disease in older women who previously have not been recognized as being at risk, a study finds.

Authors of the report, called the “Women’s Health Initiative Observational Study,” found growing evidence that inflammation has a role in the development of atherosclerosis, which is a hardening and thickening of the arteries. They point out that measuring different molecules involved in inflammation has been proposed as a way to identify and monitor patients at risk for heart disease.

In a report published in yesterday’s issue of Archives of Internal Medicine, investigators analyzed data from 72,242 post-menopausal women ages 50 to 79. The women participated in national research to assess white blood cell count as a gauge of cardiovascular events, such as heart attack or stroke, and death from any cause.

The authors focused on counting white blood cells, or leukocytes. They pointed out that this is a simple blood test that is a “stable, widely available and inexpensive measure of systemic inflammation.”

The study’s lead author, Dr. Karen L. Margolis, said previous research had “long recognized a connection” between white blood cell count and cardiovascular disease risk in men.

Doctors too often have given the white blood cell count short shrift, said Dr. Margolis, associate director of Minnesota’s Hennepin County Medical Center’s Berman Center for Clinical Research.

She said the medical world has given far more attention to concentrations of a molecule known as C-reactive protein (CRP), which is produced in the liver, and which “appears to be a cause of or marker for inflammation in the body.”

At the start of this study, which began in 1994 and ended in 2003, the white blood cell count of each participant was measured. Women then were divided into four levels or quartiles according to those measurements.

The fourth quartile comprised women with the highest white blood cell count. Those with the lowest counts were in the first quartile.

Only women who were entirely free of clinical cardiovascular disease and cancer at the start of the study were included.

“Our findings suggest that a white blood cell count higher than 6.7 is associated with a doubling in the risk of heart disease death … whether or not a post-menopausal woman smokes, has diabetes or high blood pressure, or has cholesterol problems,” Dr. Margolis said.

The study also found that women in the highest quartile “also had a 40 percent higher risk of nonfatal myocardial infarction [heart attack], a 46 percent higher risk for stroke, and a 50 percent higher risk for total mortality.”

“When there is no evidence of infection and the white cell count is elevated, it should set off an alarm bell, because WBC is a very strong predictor of cardiovascular events, even if a patient is otherwise healthy,” she said.