A system in which people have to opt out of organ donation could improve the shortage of available organs, but presumed consent is not a silver bullet, estimates show.

Every year in the US, about 7,500 people die waiting for an organ transplant, and experts expect that number to increase in coming years as demographics shift.

“Thousands of patients are dying yearly while awaiting transplantation and one reason for that is simply lack of organs,” says Neehar Parikh, a transplant hepatologist at the University of Michigan Medicine. “Based on the experience of other countries that have instituted presumed consent policies, a similar system in the US could alleviate some of this burden.”

But even with the most optimistic estimates, presumed consent would only reduce the waiting list by a marginal amount, researchers say.

“It speaks to the magnitude of the deficit we have for organ transplantation in the US,” says Parikh, an author of the new paper. “At the same time, we did find that such a policy could potentially translate to large gains in life years for the thousands of patients awaiting organ transplantation in the US.”

Opt-out organ donation estimates

Researchers used data from the Organ Procurement and Transplantation Network Standard Transplant Analysis and Research files to build a computer model to simulate how such a policy shift would affect patients on the waiting list for a heart, kidney, liver, lung, or pancreas between 2004 and 2014.

Published in JAMA Network Open, the findings show that opt-out, or presumed consent, would have added between 4,300 and 11,400 life years for the more than a half million patients on the list during the study period.

Under the most conservative estimate, it would have reduced the number of people taken off the list due to illness or death by between 3% and 10%. And under ideal circumstances, it might have decreased waitlist removals by 52%—still not enough to completely provide organs to everyone who needs one in time.

It might seem like a simple equation—one available organ equals one life saved. The reality, however, is much more complicated, researchers say. A complex web of factors including organ location, patient compatibility, whether organs are given to the sickest patients, and, ultimately, the judgement of surgeons and other clinicians affects the on-the-ground effect of organ transplants, researchers say.

“Organ donation is such a personal thing, and generally surgeons and other clinicians are looking at one patient at a time. But it’s also useful to take sort of a 50,000-foot view of all the levers we can pull to see which ones can improve outcomes for the most patients. That’s the kind of thing that engineers like me can bring to the conversation,” says first author Luke DeRoos, a doctoral student in the industrial and operations engineering department.

‘Need to increase donation dramatically’

Other countries have adopted presumed consent policies with mixed results. Previous studies of those cases suggest that it can lead to an organ donation increase of 5%-25%. In the new model, researchers simulated increases within this range.

With the current opt-in system, the US has one of the highest organ donation rates in the world, and so the gains other countries have seen might not materialize here, the researchers say.

There’s a lot of uncertainty of what effect such a system would have. While just over half of American adults are registered donors, surveys have shown that up to 93% support organ donation. Lack of consent may play a role in preventing donations from up to 40% of otherwise eligible donors, researchers say.

“Everyone in the transplant field has very strong opinions about opt-out donation, one way or the other. And so we’ve tried to be very objective, understanding that there is a lot of uncertainty around our estimates,” DeRoos says.

“There are numerous strategies for increasing organ donations, so I hope that policymakers can take numbers like these to get an idea of what the impact such a policy may be associated with.”

Parikh underscores that many different tactics will need to work in tandem to address the growing need.

“The US population is aging with more comorbidities, making the pool of organ donors smaller,” Parikh says. “There are several novel technologies, like machine perfusion of organs that can increase the utility of marginal organs, so we can use more of them for transplant. Another way to increase the donor pool is to break down barriers to living donation of kidneys and livers.

“However, to really push the needle in terms of impacting the waitlist we need to increase donation dramatically, and presumed consent is one strategy that has been proposed to potentially do that.

“But, our study has shown that it will likely not be enough to alleviate the organ shortage on its own. Nevertheless, given its potential impact, we believe this policy warrants further debate and study.”

Source: University of Michigan

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