Dr Vianda Stel:

I am Vianda Stel. I'm the director of the ERA registry. This is a registry collecting data on dialysis and kidney transplant patients in Europe. And we are located in Amsterdam, in the Amsterdam UMC.

Dr Rachel Hellemans:

My name is Rachel Hellmans. I'm a transplant nephrologist from the Antwerp University Hospital in Belgium. And today we will talk about our study in which we explored the margins of survival benefit with diseased kidney transplantation by using a target trial emulation.

What are the current unmet needs in deceased donor kidney transplantation, and what is the importance behind the target trial emulation?

Dr Rachel Hellemans:

Well, it's obvious that kidney transplantation is the best option for many of our patients with kidney failure, as it often leads to a substantially better survival compared to continuing dialysis. But over the last 20 years, we have really pushed the limits and we are now offering transplantation to much more older people and people with more comorbidities.

But due to organ shortage, we increasingly rely on less-than-optimal donor kidneys, like older donors or donation after circulatory death donors. And meanwhile, also improved care for CKD patients and dialysis patients has led to an improved survival on dialysis. So from these important evolutions came our question on how far can we go, and where do the margins lie of a survival benefit for transplantation?

What was the study design and patient population?

Dr Vianda Stel:

For this study we used the ERA registry data. This is a database on dialysis and kidney transplant patients, and for this specific study we needed to collect extra data on the donor quality. And that makes this database very unique because we have data on dialysis patients and kidney transplantations and even data on the donor type.

This makes it possible to compare the transplant survival benefit and also the dialysis survival. But if you would like to compare the survival of transplantation in dialysis patients, you ideally would like to do a randomised controlled trial. But that's not possible, it's not ethical to randomise people into a transplant group and a dialysis group.

So what we did is to do target trial emulation and in this way you emulate a randomised controlled trial and try to come as close as possible to a randomised controlled trial result. This is a quite complicated method, but what we did is to emulate a trial and to that extent try to reduce main biases, what you have usually had in observational studies.

What were the key findings?

Dr Rachel Hellemans:

The key findings were that, as we already expected, good, young donor kidneys, which we call standard criteria donor kidneys, they still lead to a substantial survival benefit compared to dialysis, even for very old patients and even for patients with diabetes or a history of cardiovascular disease.

But we are actually the first to demonstrate that there are some limits in this survival benefit when you use older donor kidneys, which we called expanded criteria donor kidneys. We see that patients over 70, 75 only have a very small to even no survival benefit with such kind of transplantation compared to continuing dialysis. And this is very important for patient counseling.

What are the take-home messages for practice?

Dr Rachel Hellemans:

So the key take-home messages from our study are first, when you want to determine someone’s suitability for transplantation, don't focus only on the patient's characteristics itself because also the donor quality will be very important for the outcomes. So you also have to take the options of the donor options into account.

And the second take-home message is that if patients aged 75 year old come for transplant counseling, we now have the data to tell them that, in case the chances of getting a standard criteria donor kidney in this particular country is very low for this patient and he will likely get an expanded criteria donor, then the patient should not expect much of survival benefit compared to continuing dialysis.

And the patient should realise that the early post-transplant phase will be risky. There will be about a two to three times higher risk of dying in the first months post transplant compared to continuing dialysis. Which doesn't mean that we will discourage this kind of transplantation, but we think it's very important that patients should realise the risks before entering onto the waitlist.