Simulated Outcomes: New Algorithm

Under the new allocation algorithm, each potential recipient of a given donor kidney will be given a continuous allocation score for that match. This continuous allocation score will them be used to rank potential recipients relative too each other.
Simulations of the new algorithm indicate that, on average, kidney allocation scores will be driven mainly by waiting time.
A breakdown of the mean score components by age, however, indicates that the quality of the HLA match contributes far more to the allocation score at younger ages. That is, on average, a patient’s rank in allocation is driven by HLA matching at younger ages, and by waiting time at older ages.

The probability of offer conversion is higher under the new algorithm, meaning fewer offers would need to be made.
Simulations of the new algorithm indicate fewer allocations above rank 15 and more below rank 5, indicating greater system efficiency overall.
The new algorithm would result in a similar amount of shipping of kidneys interstate compared to the current system (an average of 25.8% of kidneys shipped compared to 25.3% under the current system).
State balancing under the new system would be preserved relative to the status quo.

Simulations indicate that the extent of prognosis matching would be improved by the new algorithm, with a greater concentration of low KDPI kidneys allocated to low EPTS recipients and high KDPI kidneys to high EPTS recipients.
Older patients are allocated higher KDPI kidneys under the new allocation algorithm. This is driven by the extra weighting of prognosis matching at each extreme of the matching – including extra weighting for high KDPI to high EPTS transplants.

Simulations indicate much better HLA-DR matching under the new allocation system, especially for young people especially, with far fewer 2-DR or 2-DQ mismatches observed.
HLA-matching outcomes are also significantly improved for ethnic minority groups under the new system, with fewer 2-DR or 2-DQ mismatches observed.

The blood group rules that have been applied under the new algorithm are designed to:
- Expand the available donor pool for very highly sensitised A and B patients
- Expand the available donor pool for moderately to highly sensitised AB patients
- Expand the donor pool for very hard to match patients
- Expand the donor pool to facilitate good prognosis matches for young AB patients
- Avoid diverting too many O kidneys from O recipients.
These rules have produced a modest reduction in the rate at which O kidneys are diverted from O donors.

Transplant rates are expressed per 100 active patient years and take into account waiting time accumulated by patients who have not yet been transplanted. They do not reflect, however, accumulated waiting time on dialysis before being listed for transplantation, therefore transplant rates for certain subgroups (e.g. Indigenous Australians) need to be interpreted with caution.
The most significant change in the transplant rate as indicated by the simulations is the increase for the 18-34 year age group. This is the outcome of greater weighting given to good HLA matches in this age group under the new algorithm.

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