A new kidney allocation policy in Chile: computer-based simulations

Kidney allocation should reach a balance between equity and efficiency. In Chile kidneys are allocated based on ABO matching, first to medical priorities and then according to a point scheme considering human leukocyte antigen (HLA) match (60%), waiting list time (20%), and panel-reactive antibodies (PRA; 20%); pediatric recipients receive extra points. A new policy maintains ABO matching and medical priorities as the first step, but incorporates other successive steps: previous living donors donors, 0 mismatch, pediatric recipients, and finally all other recipients according to a point scheme incorporating recipient age, HLA match, PRA, and time on waiting list with similar proportions. We compared the resulting transplantations using the new versus the older allocation policy.

We analyzed computer-generated simulations using actual patients (N = 1176) on the Chilean waiting list in 2011 with the 300 donors over the previous 3 years.

The new policy a significantly decreased recipient age from 43 ± 0.3 years to 41 ± 0.3 and increased the number of 0-mismatched transplantations from 3% to 4%. The mean HLA mismatch increased from 2.8 ± 0.1 to 3.6 ± 0.1. Waiting time increased from a mean of 38 ± 1 months to 40 ± 1 months, but patients remaining on the waiting list had less waiting time with the new rule.

With the proposed changes younger patients are being privileged and the importance of compatibility is diminished (except for 0-mismatched transplantations). The chance of a good match is directly related to the size of the recipient pool, thus an allocation policy that privileges HLA matching in a restricted recipient pool is especially unfavorable for younger patients. Including age of the recipient as a continuum can help to compensate for this lack of equity. Computer-generated simulations can help discern which policies are best suited for each country based on their local characteristics.