FORT LAUDERDALE—It may be time for the Centers for Disease Control and Prevention (CDC) to redefine which kidney donors should be considered at high-risk for transmitting viral and other infections, a researcher said.

The CDC classification for high-risk kidney donors was established in the 1980s during the height of the AIDS epidemic.  At that time, clinicians had to rely on antibody testing, so the “window period” from infection to detection could be up to three months.

Now, because of better tests, this window period may be as little as 10 days, according to Robert Montgomery, MD, Director of the Comprehensive Transplant Center at Johns Hopkins School of Medicine in Baltimore. The current scheme for classifying kidney donors as being at high risk for transmitting infections has been rendered antiquated by the advent of nucleic acid testing (NAT), such as polymerase chain reaction (PCR) assays.

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Kidney transplant teams are in a conundrum when it comes to using kidneys from donors who have a history of high-risk behavior for HIV, hepatitis B, and hepatitis C.  “Very often when you are on-call you are offered organs from young perfect donors who have had high-risk behavior,” Dr. Montgomery said. “It might be drug use or homosexuality or in the sex trade or something like that.”

The problem was that transplant teams had to wait for antibody formation before ordering serologic tests. “But now, with PCR, we have the ability to detect the virus before the person has mounted an immune response. So the window period is now anywhere from 10 days to two weeks,” Dr. Montgomery said.

Many high-quality organs are being discarded at time when the nation has an acute short of donor kidneys and a high death rate among those on a transplant waiting list, he said. Dr. Montgomery contends that the CDC should reclassify some high-risk donors as low-risk after they have had nucleic acid testing for HIV and other pathogens.

Researchers at Johns Hopkins have been looking at different subpopulations of recipients and analyzing their risk of dying while waiting for an organ versus the very small risk of acquiring a virus from a high-risk donor.

“Getting a transplant can significantly improve a person’s quality of life and you have to balance that against the very low risk of contracting a viral illness,” said Dr. Montgomery, who spoke with Renal & Urology News at the American Society of Transplant Surgeons 10th Annual State of the Art Winter Symposium here.

He and his colleagues have analyzed populations that might benefit in terms of life expectancy from taking this relatively small risk. They developed a formula suggesting that older recipients (age 70 years and older) may significantly benefit from organs that in the past would have been discarded.

The risk of acquiring hepatitis C is much different in a 70-year-old compared with a 30-year-old because many of the most severe manifestations of the disease may not occur for up to 20 years, well beyond the life expectancy of a 70-year-old kidney recipient.

Dr. Montgomery said he and his colleagues are still trying to determine the optimal equations for transplanting organs from high-risk donors into older patients who have been on the waiting list for longer than five years.

He hopes that transplant centers across the country can adopt the more “donor-friendly” type of system that he and his team are proposing. “I think it is getting ready for prime-time but we need to proceed with great care,” Dr. Montgomery said.

All organ procurement organizations should adopt NAT because it could allow for use of high-risk donor organs, he said.