Based on a comprehensive analysis comparing the 12 months before and after implementation of the kidney allocation system (KAS), a number of key system goals continue to be met. This analysis was performed on behalf of the OPTN Kidney Transplantation Committee and contains additional metrics beyond those included in previous reports.
Trends include the following:
- The volume of deceased donor kidney transplants performed increased by 4.6 percent from the year prior to KAS implementation to the year afterward. This appears due to a substantial increase in deceased donation in 2015.
- Transplants for the most difficult-to-match patients, those with a very high calculated panel reactive antibody (CPRA), increased roughly five-fold for the year. Transplants for recipients with a CPRA of 99 to 100 percent were more frequent in the first six months and have since diminished somewhat, most likely reflecting an early bolus effect.
- Due to the longevity matching component of KAS, fewer transplants are occurring in which the kidney is predicted to outlive the recipient. Prior to KAS, 14 percent of kidneys expected to last the longest (with a Kidney Donor Profile Index [KDPI] of zero to 20 percent) went to recipients age 65 or older, but this dropped to 5 percent post-KAS. While transplants have declined for patients in the 50-64 and 65 and older age groups, over half of all deceased donor kidney recipients under KAS have been age 50 or older.
- Transplants have increased substantially for patients with five or more years on chronic maintenance dialysis, owing to the back-dating of dialysis time for determining waiting time points under KAS.
- Transplants have increased for African-Americans, who tend to stay disproportionately longer on dialysis prior to being listed for a transplant. African-Americans are also more likely to have blood type B compared to other candidates, so the five-fold increase in the number of A2/A2B to B transplants may also be contributing to this population’s increased access. However, only three percent of blood type B patients have been listed as eligible for these subtype-compatible kidneys, suggesting further growth in this area may be attainable.
- The kidney discard rate initially rose after KAS but in June to September 2015 was substantially the same as the period before KAS implementation. However, for the entire post-KAS year the discard rate rose from 18.5 percent pre-KAS to 19.3 percent. The majority of discarded kidneys had a Kidney Donor Profile Index (KDPI) between 86 and 100 percent.
- Transplants for pediatric patients (age 0-17) declined slightly; however, this difference is not statistically significant, and pediatric access to transplants remains 5 times higher than most adults. Pediatric recipients are also more often receiving kidneys expected to last longer (lower KDPI) under KAS compared to previously.
- Transplant rates for the small number of prior living donors that are registered on the waiting list have not changed statistically and remain sharply higher than for all other subpopulations.
- More kidneys are now being shared across donor service area (DSA) boundaries. Previously about 20 percent of kidneys were transplanted outside of the recovering OPO’s DSA, and this has increased to about 32 percent under KAS. There was a notable increase in acceptance of kidney offers outside the recovering OPO’s DSA for candidates with a CPRA of 99 to 100 percent.
- Of 230 kidney transplant programs active during the time studied, 54 percent either experienced an increase in transplant volume or experienced no change in volume.
- The percentage of transplant recipients experiencing delayed graft function (DGF) has risen from 25 percent to 29 percent, which may be influenced by the increase in recipients who have been on dialysis longer-term. In addition, the six-month graft survival rate (organ function post-transplant) decreased slightly but continues to exceed 95 percent. The slight decrease is statistically no different from the pre-KAS period.
- The OPTN/UNOS Kidney Transplantation Committee will continue to analyze these trends carefully, as well as other data that will be available longer-term.
- These recent findings are based on limited data. They must be interpreted cautiously and further tracked to assess whether observed trends will be sustained.
For additional reference, consult the “Early View” article in the online version of American Journal of Transplantation:
Stewart DE, Kucheryavaya AY, Klassen DK, Turgeon NA, Formica RN, Aeder MI. Changes in Deceased Donor Kidney Transplantation 1 Year After KAS Implementation. Am J Transplant 2016. doi:10.1111/ajt.13770