Blood Supply: How Safe Is Safe Enough?

NEW YORK

The good news is that the blood supply is safer than ever before, with dramatic decreases in the risk of contracting HIV, hepatitis B, or hepatitis C from a blood transfusion in the U.S.

The bad news? Further efforts to increase the safety of blood carries a hefty price tag because millions of units of blood need to be tested to prevent infections in a handful of people, according to a report in the Annals of Internal Medicine. And the efforts needed to reach a "zero risk" blood supply may not only be costly but also have unanticipated side effects that could offset the benefits, according to lead author Dr. James AuBuchon, of the pathology department at Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire.

"This success poses new dilemmas, and uncertainty remains about how safe the blood supply in the United States can, or should, be and how much of our limited resources should be spent on making it safer," reported AuBuchon.

In the early 1980s, HIV may have contaminated as many as 1 in 100 blood units, hepatitis C (HCV) was in 1 in 200 units, and hepatitis B (HBV) was in 1 in 2,100 units of blood. Now, HIV contaminates about 1 in 680,000 units, HCV is in 1 in 100,000 units, and HBV contaminates 1 in 63,000 units of blood. The declines are largely due to more strict screening of donors for risky behaviors, as well as testing of the units for signs of the viruses.

Most economists believe such tests are cost effective if the price tag is less than $50,000 per quality-adjusted life-year. The introduction of HIV antibody testing was extremely cost effective, with a price of $3,600 per quality-adjusted life year, according to the report.

"In contrast, many recent and proposed safety initiatives do not measure up when compared with other medical interventions," the authors wrote. HIV antibody testing is very effective, but it can take up to six months for an HIV-infected individual to make antibodies to the virus. If such a person does not admit to risky behavior and gives blood during this window of time, the test will not pick up the virus.

Although a new type of test that detects HIV's p24 antigen can pick up the virus itself, the cost is an estimated $2 million per quality-adjusted life-year saved, the authors noted. The test is projected to prevent eight transfusion-related infections per year in the U.S., a 25% reduction in HIV transfusion transmissions.

However, a far greater threat from blood transfusions, according to the study authors, is that a person might accidentally be given the wrong blood type, a potentially life-threatening mix up that occurs in about 1,000 patients every year.

In ongoing efforts to decrease the cost of health care, "decision makers are faced with critical choices among health care improvement options that pit improved blood safety against other worthwhile effective interventions," the authors concluded."

Physicians must also widen the horizons of persons who are concerned about blood safety to consider all of the health threats faced during transfusion -- including, for example, mistransfusion -- so that limited resources are expended to increase overall safety to the greatest extent possible."