KANSAS CITY, Mo. - A stay at the hospital can be draining in more ways than patients and doctors realize, researchers at St. Luke's Hospital of Kansas City say.
Those frequent tests that suck tube after tube of blood out of patients' arms can lead to anemia serious enough not only to leave patients tired and short of breath but to even raise their risk of dying.
"A lot of the blood work done in a hospital is very important and necessary," said St. Luke's heart specialist Mikhail Kosiborod. "But the volume of blood drawn is a risk factor."
Doctors have long assumed that hospital-acquired anemia was caused by bleeding during surgery, Kosiborod said. But anemic patients are no more likely to suffer such complications, he said.
Kosiborod said he and the team of researchers from St. Luke's and several other medical centers are the first to trace the likelihood of acquired anemia among heart-attack patients to the number of blood tests they receive.
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In a study published online by the journal Archives of Internal Medicine, the researchers looked at data on 17,000 heart-attack patients from 57 hospitals.
None of these patients had anemia - depleted levels of red blood cells that carry oxygen - when they entered the hospital, but one in five developed moderate to severe anemia during their hospital stay. The more blood they had drawn, the greater was their risk.
On average, the patients with hospital-acquired anemia had a total of 6 ounces of blood drawn, twice as much as the patients who didn't become anemic.
That may not seem like much; it's less than half what a blood donor gives at one sitting. But blood donors are healthy. Their bone marrow replenishes red blood cells quickly.
"People who are healthy, they won't even feel (the blood loss)," Kosiborod said. "Hospital patients are not healthy people. Their bone marrow isn't as capable."
Previous research by Kosiborod and his St. Luke's colleagues found that months after leaving the hospital, heart-attack patients with acquired anemia were having a harder time than non-anemic patients doing activities such as housework and shopping.
Fatigue from the anemia may make heart-attack survivors reluctant to go back to work or do the supervised exercise that is key to cardiac rehabilitation, said Adam Salisbury, also a St. Luke's heart specialist and lead author with Kosiborod on the new study.
Even more concerning, the St. Luke's researchers have found that patients were 82 percent more likely to die within a year of their heart attacks if they had developed moderate to severe anemia in the hospital.
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