"We found that regardless of other factors, late-life anemia doubled the risk of death and increased the risk of hospitalization by 40 percent," said Brenda Penninx, Ph.D., associate professor of gerontology. "This suggests that clinicians should be aware of patients' anemia status, even if they have no apparent disease."
Anemia, which is a reduced level of oxygen-carrying red blood cells, affects about 13 percent of people over age 70. It has a variety of causes, from iron or vitamin B-12 deficiencies to chronic diseases such as cancer or liver disease. About 30 percent of cases in older adults are unexplained; they are not related to underlying conditions and are not linked to nutrition.
The researchers examined the relationship of anemia to death and hospitalization in a group of 3,607 adults age 71 and older from East Boston, Mass., New Haven, Conn., and Iowa and Washington counties in rural Iowa who participated in "Established Population for Epidemiologic Studies of the Elderly," a project sponsored by the National Institute on Aging.
Anemia was present in about 12.5 percent of participants. They were followed for an average of four years. During this period, participants with anemia were more likely to die and to be hospitalized than non-anemic participants. Those with anemia also had significantly longer hospital stays.
Penninx said the relationship between of anemia to death and hospitalization was present whether or not the participants had diseases associated with anemia, such as cancer and kidney failure. This indicated that the disease itself did not explain the increased risk. The researchers adjusted for other factors that might affect the results, such as age, sex, cigarette smoking, and blood pressure, and again found that anemia itself is highly associated with risk.
The researchers also found that participants with borderline anemia were at increased risk. "A higher hemoglobin level was significantly associated with a lower risk of mortality and a lower risk of hospitalization," said Penninx.
The researchers are not sure exactly how hemoglobin levels and the increased risk are linked. Hemoglobin is the oxygen-transporting agent in red blood cells.
"A major question is whether anemia is an independent risk factor for physical decline or merely a surrogate marker of chronic disease or the aging process itself," says Penninx. "While we don't yet understand the relationship, our findings suggest that anemia may help identify frail older persons."
Earlier this year, the researchers reported that older adults with anemia are almost twice as likely to have a significant decline in physical performance that could threaten their independence.
"Our research suggests that anemia deserves more attention," said Penninx. "It seems to be an important risk factor for physical decline and is potentially treatable. We need to learn whether treatment can help restore physical function and prevent hospitalizations and death."
Other researchers involved in the project were Marco Pahor, M.D., with Wake Forest; Richard Woodman, M.D., with Ortho Biotech Products, L.P.; and Luigi Ferrucci, M.D., and Jack M. Guralnik, M.D., Ph.D., with the National Institute on Aging. Data analyses were supported through Ortho Biotech Products, L.P.
Wake Forest University Baptist Medical Center is an academic health center located in Winston-Salem, N.C., that is comprised of North Carolina Baptist Hospital and Wake Forest University School of Medicine.
Media Contacts: Karen Richardson, (krchrdsn@wfubmc.edu), Shannon Koontz (shkoontz@wfubmc.edu) at 336-716-4587.