Goodnough, who has devoted much of his career to blood conservation, notes that the use of blood briefly declined in the early 1980s in response to the AIDS epidemic, as well as to the widespread problem of hepatitis C infection among transfused patients undergoing heart surgery. However, with the advent of intensive screening and other safety measures, the number of transfusions began steadily rising, largely because of the demands of specialized care and an aging population, he said.
Today, some 24 million blood components, including red blood cells, plasma and platelets, are transfused annually in the United States. Among the 39 million patients discharged annually from U.S. hospitals, 2.3 million—or 5.8 percent—received transfusions, according to the report.
The downward trend in blood usage began in 2009, largely in response to the rising costs of blood, which can run between $500 and $1,000 for each transfused unit, Goodnough said. For the first time, transfusions of blood components provided by the American Red Cross, which collects about half of the nation's supply, fell by 3 percent in both 2009 and 2010, he said.
That trend has continued, with subsequent decreases of 3 percent in 2011 and 5 percent in 2012, Red Cross officials recently reported at a meeting of the International Society of Blood Transfusion.
He said physicians' experiences treating Jehovah's Witnesses, who object to transfusion for religious reasons, and the publication of findings from four key clinical trials have contributed to the growing recognition that patients can do just as well with less blood during treatment. But there is no standard guideline, and some controversy, regarding what level of hemoglobin should trigger a transfusion, he said. He said he believes every patient needs to be evaluated individually.
"I don't think there is one laboratory value that should be used. Older patients may be different than younger patients, for instance," he said. "So the message is that there is not one number. We should use a restrictive transfusion philosophy—when the treating team is convinced that the benefits of transfusion would outweigh the risks."
Despite growing evidence about the dangers of unnecessary transfusions, he said there continues to be a wide variation in practices across the country, suggesting blood is often used inappropriately.
"If you look, for instance, at patients undergoing coronary artery bypass surgery, there is widespread variability throughout the United States for a routine bypass or valve replacement on transfusion outcomes, with regional differences and differences among academic and community medical centers," he said.
He said the American Medical Association has highlighted the danger of unnecessary transfusion and included blood transfusion among a list of five overused treatments. (The others were heart stents, ear tubes, antibiotics and the induction of birth in pregnant women.)
Yet changing clinical practice to ensure that every transfusion is necessary and appropriate remains a challenge, Goodnough said.
"The big question is how to best translate these findings into clinical practice… and overcome clinicians' resistance to change," he said.