Reevaluation of the Kidney Donor Risk Index.

BACKGROUND: The Kidney Donor Risk Index (KDRI) is a score applicable to deceased kidney donors which reflects relative graft failure risk associated with deceased donor characteristics. The KDRI is widely used in kidney transplant outcomes research. Moreover, an abbreviated version of KDRI is the basis, for allocation purposes, of the "top 20%" designation for deceased donor kidneys. Data upon which the KDRI model was based used kidney transplants performed between 1995 and 2005. Our purpose in this report was to evaluate the need to update the coefficients in the KDRI formula, with the objective of either (a) proposing new coefficients or (b) endorsing continued used of the existing formula. METHODS: Using data obtained from the Scientific Registry of Transplant Recipients, we analyzed n = 156069 deceased donor adult kidney transplants occurring from 2000 to 2016. Cox regression was used to model the risk of graft failure. We then tested for differences between the original and updated regression coefficients and compared the performance of the original and updated KDRI formulas with respect to discrimination and predictive accuracy. RESULTS: In testing for equality between the original and updated KDRIs, few coefficients were significantly different. Moreover, the original and updated KDRI yielded very similar risk discrimination and predictive accuracy. CONCLUSIONS: Overall, our results indicate that the original KDRI is robust and is not meaningfully improved by an update derived through modeling analogous to that originally employed.

Patient selection and volume in the era surrounding implementation of Medicare conditions of participation for transplant programs.

OBJECTIVE: To evaluate evidence of practice changes affecting kidney transplant program volumes, and donor, recipient and candidate selection in the era surrounding the introduction of Centers for Medicare and Medicaid Services (CMS) conditions of participation (CoPs) for organ transplant programs. DATA: Scientific Registry of Transplant Recipients; CMS ESRD and Medicare claims databases. DESIGN: Retrospective analysis of national registry data. METHODS: A Cox proportional hazards model of 1-year graft survival was used to derive risks associated with deceased-donor kidney transplants performed from 2001 to 2010. FINDINGS: Among programs with ongoing noncompliance with the CoPs, kidney transplant volumes declined by 38 percent (n = 766) from 2006 to 2011, including a 55 percent drop in expanded criteria donor transplants. Volume increased by 6 percent (n = 638) among programs remaining in compliance. Aggregate risk of 1-year graft failure increased over time due to increasing recipient age and obesity, and longer ESRD duration. CONCLUSIONS: Although trends in aggregate risk of 1-year kidney graft loss do not indicate that the introduction of the CoPs has systematically reduced opportunities for marginal candidates or that there has been a systematic shift away from utilization of higher risk deceased donor kidneys, total volume and expanded criteria donor utilization decreased overall among programs with ongoing noncompliance.

Variation in access to the liver transplant waiting list in the United States.

BACKGROUND: We sought to compare liver transplant waiting list access by demographics and geography relative to the pool of potential liver transplant candidates across the United States using a novel metric of access to care, termed a liver wait-listing ratio (LWR). METHODS: We calculated LWRs from national liver transplant registration data and liver mortality data from the Scientific Registry of Transplant Recipients and the National Center for Healthcare Statistics from 1999 to 2006 to identify variation by diagnosis, demographics, geography, and era. RESULTS: Among patients with ALF and CLF, African Americans had significantly lower access to the waiting list compared with whites (acute: 0.201 versus 0.280; pre-MELD 0.201 versus 0.290; MELD era: 0.201 versus 0.274; all, P<0.0001) (chronic: 0.084 versus 0.163; pre-MELD 0.085 versus 0.179; MELD 0.084 versus 0.154; all, P<0.0001). Hispanics and whites had similar LWR in both eras (both P>0.05). In the MELD era, female subjects had greater access to the waiting list compared with male subjects (acute: 0.428 versus 0.154; chronic: 0.158 versus 0.140; all, P<0.0001). LWRs varied by three-fold by state (pre-MELD acute: 0.122-0.418, chronic: 0.092-0.247; MELD acute: 0.121-0.428, chronic: 0.092-0.243). CONCLUSIONS: The marked inequity in early access to liver transplantation underscores the need for local and national policy initiatives to affect this disparity.

Insurance type and minority status associated with large disparities in prelisting dialysis among candidates for kidney transplantation.

BACKGROUND AND OBJECTIVES: Disparities in time to placement on the waiting list on the basis of socioeconomic factors decrease access to deceased-donor renal transplantation for some groups of patients with end-stage renal disease. This study was undertaken to determine candidate factors that influence duration of dialysis before placement on the waiting list among candidates for deceased-donor renal transplantation in the United States from January 2001 to December 2004 and the impact of Medicare eligibility rules on access. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Access to the waiting list was measured as the percentage of all wait-listed candidates in the Scientific Registry of Transplant Recipients database who were listed before dialysis and by the duration of dialysis before placement on the waiting list. Multivariate logistic and linear regressions were used to determine variables that were predictive of preemptive listing and the duration of dialysis before listing. RESULTS: The odds for preemptive placement on the waiting list improved during the course of the study period, whereas the median duration of prelisting dialysis did not. The candidate factors that were associated with low rates of preemptive listing and prolonged exposure to prelisting dialysis included Medicare insurance, minority race/ethnicity, and low educational attainment. In patients who were listed after the age of 64 yr, the adverse effect of Medicare insurance on access largely disappeared. CONCLUSIONS: The disparity in dialysis exposure could potentially be diminished by concerted efforts on the part of the nephrology and transplant communities to promote early referral and preemptive placement on the waiting list, by calculating waiting time from the date of initiation of dialysis for patients who are on dialysis at the time of referral, and by relaxing Medicare eligibility requirements.

Development and current status of ECD kidney transplantation.

The worsening shortage of donor kidneys for transplant and the aging of both the donor and candidate populations have contributed to the increasing importance of ECD kidney transplantation. While ECD transplants have an increased risk of graft failure, for most candidates patient survival is still improved over remaining on dialysis. Because of this risk, however, ECD kidneys have a high likelihood of discard; significant geographic variation in discard and transplant rates impedes maximum utilization of these kidneys. The ECD allocation system was implemented to help facilitate expeditious placement of ECD kidneys to pre-consented candidates by a simplified allocation algorithm. Under this system, recovery and transplantation of ECD kidneys have increased at rates not seen with non-ECD kidneys and not predicted by preexisting trends. More disappointing has been the lack of effect on the percentage of discards and DGF, despite significant reductions in CIT. The disadvantage in graft survival for ECD kidneys extends equally across the spectrum of recipient characteristics, such that no one group of candidates has a proportionately smaller increase in risk. However, benefit analyses comparing the risk of accepting an ECD kidney versus waiting for a non-ECD kidney demonstrate a significant ECD benefit for older and diabetic candidates in regions with prolonged waiting times. The potential value of an ECD kidney to an individual candidate hinges upon the ability to receive it substantially earlier than a non-ECD kidney. Thus, future allocation efforts may focus on ensuring that is the case. In allocation driven by net benefit, ECD kidneys may become an alternative for those who might not otherwise receive a kidney transplant.

Effect of changing the priority for HLA matching on the rates and outcomes of kidney transplantation in minority groups.

BACKGROUND: HLA typing and the time a patient has spent on the waiting list are the primary criteria used to allocate cadaveric kidneys for transplantation in the United States. Candidates with no HLA-A, B, and DR mismatches are given top priority, followed by candidates with the fewest mismatches at the HLA-B and DR loci; this policy contributes to a higher transplantation rate among whites than nonwhites. We hypothesized that changing this allocation policy would affect graft survival and the racial balance among transplant recipients. METHODS: We estimated the relative rates of kidney transplantation according to race resulting from the current allocation policy and racial differences in HLA antigen profiles, using a Cox model for the time from placement on the waiting list to transplantation. Another model, also adjusted for HLA-B and DR antigen profiles, estimated the relative rates of kidney transplantation that would result if the distribution of these antigen profiles were identical among the racial and ethnic groups. We also investigated the effect of HLA matching on the risk of graft failure, using a Cox model for the time from the first transplantation to graft failure. The results of the two analyses were used to estimate the change in the racial balance of transplantation and graft-failure rates that would result from the elimination of HLA-B matching or HLA-B and DR matching as a means of assigning priority. RESULTS: Eliminating the HLA-B matching as a priority while maintaining HLA-DR matching as a priority would decrease the number of transplantations among whites by 4.0 percent (166 fewer transplantations over a one-year period), whereas it would increase the number among nonwhites by 6.3 percent and increase the rate of graft loss by 2.0 percent. CONCLUSIONS: Removing HLA-B matching as a priority for the allocation of cadaveric kidneys could reduce the existing racial imbalance by increasing the number of transplantations among nonwhites, with only a small increase in the rate of graft loss.