Potential donor organs once rejected as unsafe for transplant may not be as risky as once thought, new Australian research shows.
Our research, published in the Medical Journal of Australia, suggests that injecting organs or men having sex with men could, for example, safely open up a pool of available organs. This is as long as donors negatively test for blood infections, such as HIV, hepatitis B and C.
Currently, organs from this and other groups considered to be at high risk are often dismissed directly for fear of transmitting hidden infections to the recipient.
If the transplant criteria were based on viral status rather than belonging to a particular group, we estimate that this could mean that up to 30 more people could receive a transplant per year in NSW alone.
Why are only some viruses transmitted by blood and how do they actually spread?
Which high-risk groups are usually dismissed as donors?
Many infections can be transmitted as a result of an organ transplant. But this happens very rarely due to strict management, which involves careful review and selection of donors.
Blood-borne viruses, such as hepatitis B, hepatitis C, or HIV, are of particular concern because they have historically had the most potential to have devastating effects on the organ recipient.
Some potential organ donors have behaviors that increase the risk of infection. National and international guidelines perceive high-risk groups that these viruses include:
people injecting illegal drugs
men having sex with men
people who have recently been in prison
sexual partners of any of these groups, or people with blood vessel virus.
People in these groups are often rejected as organ donors, even when blood-borne virus tests are negative and sometimes even if they are not tested.
This is due to concerns about the risk of giving a recently infected donor, but the infection still does not show with blood tests. This is known as the "window period". If the infection occurred over a period of time, humans could inadvertently transmit the virus.
When we used Australian data, here's what we found
So what are the big risks we're talking about?
Until recently, Australian guidelines have relied on risk assessments in the US, although there are important differences in the prevalence of blood-borne viruses in the US and elsewhere compared to Australia.
We believed that the risk of infection for a period of time in Australia was probably lower, perhaps significantly lower, than is being appreciated. So, we worried that potential donors who could really donate could be turned down.
So, we identified data from sources, including magazine articles, government reports and conference summaries between January 1, 2000 and February 14, 2019, to see how often blood-borne viruses are present in Australia's blood.
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We have found that, as expected, men who have sex with men are at the highest risk of HIV in Australia. But for every person testing for HIV, the risk of transmitting the virus was about one in 6,500. This is lower than the US estimate, which is 2,500 in 2,500. The difference was more pronounced among injected drug users in Australia, where 50,000 would each have a window infection, compared with one in 2,000 in the US.
The risk of a transient was higher for hepatitis C. Among the at-risk groups, this was about one in 500, similar to research abroad. There have been no studies abroad to compare hepatitis B. We have found that the risk of transient infection is at most one in 200 from the most at-risk group (though we may be cautious and overestimate this risk).
Explanation: Hepatitis A, B, C, D and E
What does that mean?
First, we suggest that all potential organ donors with high-risk behavior be evaluated with a test that provides the shortest period of time, to reduce the likelihood of a recent infection being missed.
This means testing for the presence of the virus itself (via DNA or RNA testing) rather than relying on tests looking for markers of infection (serological testing).
For potential donors who test for negativity, our data can be used to help clinicians place low risk of transmission of infection in context for organ recipients.
What is the alternative?
For most people, organ transplantation is the best treatment for organ failure and can be a lifeline.
For people with kidney failure, dialysis is an alternative. But it gives a shorter survival rate, poorer quality of life, and increases the cost to the healthcare system from kidney transplant treatment. There are no other long-term options for the heart, liver and lungs; without transplantation, people whose organs fail will eventually die.
But there are not enough organ donors to visit. About 1,500 Australians are waiting for a transplant.
Nevertheless, the possibility of receiving a donor organ with even a very low risk of transmission may not seem immediately attractive. But that has to be balanced against the considerable health consequences of transplantation and the rest on the waiting list.
In 2018, there were 554 deceased donors in Australia who donated organs to 1,543 transplant recipients. In the same period, 39 people died while waiting for a transplant and another 236 were removed from the waiting list.
Even with our newly calculated low risk of transmission, there are ways to minimize the risks of further, or new treatments, cure viral infections if transmitted.
For example, with HIV, medications could be provided to recipients to further reduce the risk of transmission. If the recipient develops hepatitis C, there are now medicines that can completely cure it. And, against hepatitis B, many people are vaccinated, which prevents transmission.
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What is happening internationally?
Providers at increased risk of blood-borne viruses are used internationally.
In the US, more than 25% of organ donors now meet these criteria, largely due to the opioid epidemic and associated increased overdose deaths.
This strategy has led to an increase in the transmission of hepatitis C from donors to recipients. But hepatitis C can be cured for eight weeks during treatment, even among transplant recipients.
Researchers have also shown an increase in survival for patients who have accepted their kidneys from people at increased risk of viral infection compared with those who chose to stay on the waiting list.
Does this mean that more people might have a transplant?
So could our work have a tangible impact on the number of Australians receiving transplants?
Our preliminary work suggests that there could be an increase in donors of up to 5% in NSW only between 2010-2015, when we accept donors of risky behavior but negative test results. There could be another five donors a year that can each donate up to six recipients (up to 30 additional recipients a year).
Our early results on the risk of infection were recently incorporated into national guidelines developed by the Society for Transplantation of Australia and New Zealand for organ transplants.
In Victoria, people waiting for a kidney transplant can now agree to receive organs at this risk when placed on a waiting list.
We hope that our research drives discussion among patients and physicians to consider what risks are important to patients and where their values and preferences lie. Better evidence for decision making should definitely help.