High cathepsin S levels were also associated with a 62 percent increased risk of death from cardiovascular disease and a small increase in death from cancer.
In the second group, men and women who showed the highest levels of the protein in their blood had double the risk of dying when compared to those with the lowest levels.
It's too early to say if there's a cause-and-effect relationship, Mariani cautioned.
Nor is it clear if the findings can be generalized to other ethnic groups (this was mostly a white European population) or other age groups.
The biomarker does seem promising because it would be easy to assess in a simple blood test. Still, it needs to be validated in further trials.
"Future studies should be performed on medications [to target this biomarker]. They need to see if intervening on this particular marker actually will improve outcomes," said Dr. Suzanne Steinbaum, director of Women and Heart Disease at the Heart and Vascular Institute at Lenox Hill Hospital in New York City.
Visit the American Heart Association for more on cardiovascular disease.
SOURCES: Thomas Mariani, Ph.D., associate professor, pediatrics, medicine and environmental medicine, University of Rochester Medical Center; Suzanne Steinbaum, D.O., director, Women and Heart Disease, Heart and Vascular Institute, Lenox Hill Hospital, New York City; Aug. 30, 2011, Journal of the American Medical Association, online
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