Blood cleansing would raise need for donors

BETHESDA, Md. -- Treating donated blood to kill HIV and other dangerous organisms also damages the blood, enough to require blood centers to scramble for more donations.

The chemicals used to cleanse blood could have unintended effects on patients that won't be evident for years. And purifying blood likely would cost community blood banks millions of dollars more each year, costs they will have to pass on to the hospitals and patients they serve.

Although experts meeting this week at the National Institutes of Health to discuss experimental blood-cleansing procedures argued in terms like hemostatic function, mutagenicity and P values, on Thursday their debate about the risks devolved into simple cliches: Baggage. Nature of the beast. No free lunch.

Officials with the Food and Drug Administration and the nation's blood banks agree they would like to make America's already-safe blood supply even safer. But they also acknowledge it's not yet clear that the cost and potential dangers of blood purification -- officially labeled Thursday as "pathogen reduction" -- are worth the benefits.

Because the risk of getting sick from a blood transfusion already is minuscule, especially for viruses such as HIV and hepatitis C, any safety problems with the new technology immediately would create more problems than it solved.

"It will be up to the blood banks to tell us if it's worth the tradeoff," said Dr. Jaro Vostal, an FDA medical officer and the conference chairman.

Dr. James AuBuchon, head of pathology at Dartmouth-Hitchcock Medical Center in New Hampshire, presented a report on the effect of pathogen reduction on blood centers, and he questioned if it's worthwhile.

"If the risk of HIV or (hepatitis C) is one in 2-million units, what risks should be acceptable? And how can we prove they are this small?"

Last month, Florida Blood Services announced it had failed to detect the presence of HIV in a donated unit of blood. Two unidentified blood recipients, including a father in his 20s, were infected.

It was only the second case of HIV contamination since American blood banks began using sophisticated nucleic acid testing in 1999, and was blamed on what's known as the window: If a donor becomes infected with HIV up to 10 days before giving blood, the levels of virus may be too low for detection.

Still, FDA officials and blood researchers say they aren't particularly concerned about HIV, because the new tests have cut the risk of infection to about one in 2-million. The same is true for hepatitis C.

They do worry about a range of bacteria present in about one in every 2,000 units of blood, and which may sicken, or even kill, an estimated one in 100,000 transfusion recipients.

Platelets, the blood's clotting agents, are most at risk for bacteria because they must be stored at room temperature. Other blood products can be frozen.

For that reason, some researchers suggested pathogen reduction should first be used to treat platelets. Others said the FDA instead should focus on developing better ways to detect bacteria accurately and quickly, tests that are lacking now and would pose no risk to patients. Plus they would be cheaper.

Vostal said both are under consideration. "Our goal is reduce bacteria in blood products," he said. "However we get there is not really that important to us."

Generally, pathogen reduction works by adding a chemical to the blood products to make the pathogens more sensitive to light, then zapping them with ultraviolet light. Other systems use chemicals to destroy the pathogens.

In both cases, the chemicals are then washed from the blood.

Dr. Sherrill Slichter, the research chief at Puget Sound Blood Center, said treating platelets reduced the survival time of platelets by 25 to 30 percent, and an additional 10 percent were lost in the process.

Although the platelets that did survive the process worked fine, the reduction was significant, and blood centers will have to collect more blood to make it up. It's not yet clear how much.

Red cells fare better than platelets, but treating them likely would require blood banks to collect at least 100,000 more units of whole blood a year, AuBuchon said. That's a fraction of the nation's blood supply, but most blood banks barely collect enough now.

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