'Calculator' used in transplant decisions

A lack of kidney donors has forced specialists to introduce a "mortality calculator" that will bump people off the transplant list if they don't meet certain criteria.

The process has left at least one patient "furious" but doctors say their hands have been forced by a dire situation where the list of people needing transplants continues to grow but the number of donors does not.

The kidney transplant survival calculator was developed in North America but has been adapted for New Zealand conditions. It was tested on patients in Christchurch for more than 18 months, and came into practice across the country this month.

Nick Cross, clinical director of the Nephrology Department at Christchurch Hospital, had a central role in introducing the calculator and said it was forced by a "very constrained environment".

The process involves doctors asking patients a number of questions and then using the calculator to assess whether they meet the threshold of an 80 per cent chance of being alive five years after transplant.

The test would be applied to anyone wanting to go on a waiting list for kidneys donated by a deceased donor. It does not apply to those who were able to get a kidney from a family member or friend.

Among those who have already been bumped off a list by the calculator is Colleen Davidson, 63.

Her kidneys had failed due to a genetic condition called polycystic kidneys, for which there is no cure.

She had been waiting for a kidney for almost eight years when she was told a mystery man wanted to donate his kidney. In February, doctors deemed it "reasonable to proceed" with the operation.

But, just a week out from the operation planned for March 13, doctors cancelled the surgery and removed Davidson permanently from the waiting list.

Doctors backed up the sudden decision with the new mortality calculator.

"I was so furious," Davidson said. "I don't know how they worked it out.

"I asked them and they just danced around the question. They kept changing their tune."

Doctors used the system to calculate she had a 60 per cent chance of surviving five years after a transplant. She needed to score 80 per cent.

Cross said the calculator would not be the only thing used to make an assessment as the tool is "pretty blunt".

For example, it asks whether a patient has heart problems but only accounts for a yes/no answer, not whether the problems are mild or severe. It also doesn't take into account some serious health complications like cancer.

Because of that, doctors had been advised to use it alongside other assessments and the system will be continually reassessed.

There is also process for an appeal.

Cross said there were more than 700 people waiting for a kidney and only about 40 were donated a year.

That rate of about eight donors per million people is well below the donor rate in Australia, Britain and the US. Australia has a rate of about 15 per million, the US and UK are about 20, Norway is about 22.

"It's been static for years and compares pretty poorly with countries round the world.

"There are a lot of people that need kidneys but there is a small pool of kidneys to be transplanted."

The new system was implemented to ensure consistent decisions were being made across the country, Cross said.

It used to be that if a specialist thought a patient needed a kidney transplant, they would refer them to a transplant centre in either Christchurch, Wellington or Auckland.

The centre and the patient's doctor would make a decision as to whether the person was a good recipient but there wasn't any way of formally assessing nor of checking whether decisions were consistent across the country.

"There was unease amongst specialists that there were differences in opinion being given in different parts across the country," Cross said.

Now, all patients will be assessed using the new calculator for the likelihood of surviving and will be reassessed every year if they stay on the waiting list.

"It is thought you have all these people waiting and so it wouldn't be fair to give it to someone who is about to die," Cross said.

"It's a little bit contentious because this isn't talking about whether you would benefit from a transplant, it's talking about whether you would benefit sufficiently enough.

"Most kidney specialists in New Zealand think that is reasonable.

"Some patients think that is fine and can understand that. Some patients think it is a bit unfair.

"It's felt that this is a community resource and it is a precious resource and we should only use it for people that would be able to benefit from it."

Kidney Health New Zealand medical director Kelvin Lynn said the organisation would make available information about what the changes mean for people contemplating going on the dead donor list.

He said it would seem harsh to some people but it was "about getting the fairest and best use of a scarce resource".

"If we had many, many more donors we would transplant more people. You have a duty to the donors to use the gift in the best way possible."

However, Davidson and her family said they were distraught and angry that doctors allowed her to get so close to the operation, just to have hope pulled away.

"They went too far. All the information they had, with all the testing, they already knew it all when they put me on the waiting list.

"I asked the doctor: ‘If I stayed well could I go back on the waiting list?' But they refused."

She now faces daily dialysis for the rest of her life. According to her medical notes, specialists initially deemed her operation "surgically feasible" and reported it was "reasonable to proceed".

Doctors wrote of a number of health concerns, but noted that none of those conditions was reason enough alone to cancel the transplant.

The decision, posted to Davidson and her family, failed to explain how the mortality calculator worked or any right to appeal the decision. She never found out who offered their kidney.


In the past five years 284 kidneys have been transplanted from deceased donors. The most was 65 in 2008. The least was 50 in 2010.

In the same time period, 296 kidneys have been transplanted from living donors.

There are about 700 people on the kidney transplant waiting list.

The success rate for kidney transplants in New Zealand is 94 per cent after one year.

This drops to 78 per cent after five years.

The number of deceased donors is about 40 per year in New Zealand.

In 2012 there were 38 people who donated their kidneys after death.

Sunday Star Times