In a recent article in Pediatric Nephrology, Charnaya and colleagues  examined the impact of changes in the Kidney Allocation System (KAS) in the USA on access to deceased donor kidney transplantation (DDKT) for children by ethnicity. KAS was introduced in the USA in December 2014, and was developed in response to several concerns including ‘higher-than-necessary’ rates of discarded kidneys, variability in access to transplant for historically disadvantaged patients, such as highly sensitised and non-white candidates, and a general mismatch of organs and candidates resulting in unrealised life years and high re-transplant rates [2, 3]. KAS sought to ameliorate this situation, improving equity to DDKT by matching high-quality kidneys (assessed using the kidney donor profile index, KDPI) to candidates with the highest estimated post-transplant survival .
While others have examined the impact of KAS on pediatric outcomes including patient and renal allograft survival, length of stay and delayed graft function [3, 5], the authors state this is the first study to specifically investigate ethnic disparities in pediatric kidney transplantation and outcomes in the post-KAS era. In addition to examining relative differences in transplant access by ethnicity and by pre/post-KAS era for each ethnic group, percentages of children pre-emptively transplanted and time to 5-year all cause graft failure (ACGF) by ethnic group in the pre- and post-KAS eras were compared to determine whether gains in access and survival had been made. Using data from two national registries, the United States Renal Data System (USRDS) and the Scientific Registry of Transplant Recipients (SRTR), several positive findings were noted. Compared with the pre-KAS era, children of Asian ethnicity were more likely to be waitlisted within 2 years of first kidney replacement therapy service in the post-KAS era, with no difference in time to waitlisting for DDKT observed by era for other ethnic groups. Asian children were more likely than White children to be waitlisted within 2 years in the post-KAS era; pre-KAS, any difference compared to White children was consistent with chance.
Compared to the pre-KAS era, a higher proportion of pre-emptive transplantations occurred; improvements in renal allograft survival were also seen for Black and Hispanic children receiving a DDKT, with 34% (95% CI 0.48, 0.91) and 37% (95% CI 0.43, 0.92) lower hazards for failure in the modern era for these groups after adjusting for age, insurance type, and cause of kidney failure, respectively.
However, while no difference in time to waitlisting was noted for Black and Hispanic children by era, compared to White children, they remained less likely to be waitlisted within 2 years of first kidney replacement therapy (KRT) service in both pre- and post-KAS eras. Hispanic children were less likely to be waitlisted compared to White children in the modern era. Black children were also more likely than White to experience ACGF in both pre- and post-KAS eras, although the effect estimates in the post-KAS era were attenuated.
Charnaya and colleagues present several key findings relating to transplant access. First, given the paper’s focus on KAS, is the issue of access to deceased donor transplant. The authors found that a higher proportion of children in the post-KAS era received a DDKT, while comparatively fewer children received a living donor transplant. Overall, higher proportions too were noted of highly sensitised recipients (calculated panel reactive antibody, CPRA > 20%), which was in keeping with previous findings [3, 6] and suggests relative success for KAS in reducing disparities across the candidate CPRA spectrum. In terms of time to DDKT from waitlisting by ethnic group, however, compared with pre-KAS, findings were essentially unchanged. This may be construed as relatively ‘reassuring’, given the suggestion of a longer time on dialysis for recipients post-KAS [3, 5] but should we be accepting of the status quo? One earlier study of DDKT rates among children post-KAS suggested rates for African American children were projected to increase following KAS implementation, although this study, with a longer follow-up, would suggest this has not been realised. In 2017, following implementation of KAS, the Organ Procurement and Transplantation Network (OPTN) published an equity in access report suggesting changes in allocation had led to more equitable access to DDKT for all waitlisted patients . Ongoing disparities, after adjusting for other factors, were largely attributable to the donor service area (DSA) of the hospital, candidate calculated panel reactive antibody (CPRA), and blood type (i.e., ABO), which could in part explain the status quo noted in this study as earlier, pre-KAS studies have shown large geographic variation in wait times for pediatric DDKT due to differential supply and demand by DSA . This finding was considered to contravene the OPTN’s Final Rule specifying that organ allocation policies ‘shall not be based on the candidate’s place of residence or place of listing, except to the extent required’, which has since led to the removal of DSA and OPTN region from kidney and kidney-pancreas transplant allocation in March 2021 . Based on simulated allocation models, DSA has now been replaced with a 250 nautical mile fixed distance radius, with a maximum of two points received for candidates living within the radius, decreasing linearly to the border at which no additional points are given. Offers are initially made to all candidates within the radius before candidates outside of the radius are approached. Initial post-policy monitoring (March–June 2021) findings cautiously suggest further improvements in transplant access: increases in DDKT across all age groups (including children) and ethnic groups are reported, with the largest increases among Black patients. Perhaps unsurprisingly, the median distance from donor hospital to transplant centre increased (70 to 125 nautical miles) as did the cold ischaemia time (17.3 to 19.3 h), although the discard rate fell from 24 to 22% . We await future studies in children to find out whether these changes have improved access to DDKT beyond that seen in this study, without compromising early outcomes.
Ultimately access to DDKT is dependent on the availability of high-quality organs for children who, once transplanted, are estimated to have a near-normal life expectancy . Globally, the need for organs far exceeds supply; in the USA in 2019, 113,000 patients were waiting for a transplant, of whom over half were of an ethnic minority background . Pediatric prioritization policies and the degree to which children are preferentially offered organs correlates with a shorter time to DDKT among European countries, as do country-level factors such as the density of pediatric transplant centres per million children and national gross domestic product (GDP) . As the USA has the highest national GDP ($23 trillion in 2021 ), changes to allocation policies which further prioritise pediatric patients and/or ameliorate geographical disparities may help improve access to DDKT.
Unacceptably, another important finding from this study is that disparities in access to waitlisting persist for Black, and Hispanic children compared to White children in the post-KAS era. It has been more than two decades since Furth et al. noted a 20% lower likelihood of waitlisting for Black children compared to White ; however, following the introduction of Share35, racial disparities appeared diminished, with improved time to DDKT for all and similar probabilities of DDKT for Black and Hispanic compared to White children seen . Why then do we observe these disparities?
Breaking down the underlying processes, timely waitlisting is dependent on multiple factors which are likely unrelated to KAS: these include timely presentation of kidney disease prior to reaching kidney failure, suitability for transplant waitlisting including appropriate management of CKD-associated comorbidities, completion of surgical assessments, up-to-date vaccinations, and psychological preparedness, but also clinical decisions on when to prepare for transplant and waitlist, as well as family readiness and consent . We know that racial differences exist in many of the processes prior to waitlisting, although in others there are few data. Compared to White US children, Black and Hispanic children are less likely to receive specialist kidney input prior to developing kidney failure, suggesting delayed referral to nephrology care ; similarly, non-White ethnicity and a lack of insurance was associated with late initiation of dialysis among children captured in the USRDS dataset . From the chronic kidney disease in children (CKiD) study, we recognise that African American children are disproportionately affected by glomerular disorders with a higher risk of kidney function decline and progression to failure in part due to the associations with the apolipoprotein L1 APOL1 genotype , which may in part account for differences in timely presentation. The French national renal registry data demonstrates that diseases at high risk of recurrence or progression, as well as emergency initiation of dialysis are associated with lower likelihood of pre-emptive transplantation or waitlisting within 6 months of KRT start ; due to ethnicity data collection not being permitted in France, it is not clear if this association is driven by differences in ethnicity; however, it is conceivable that underlying biological differences may influence access to waitlisting for US children.
Entangled in the issue of racial health differences is the influence of socioeconomic status. In a CKiD cohort with non-glomerular disease, African American children had a shorter time to KRT than non-African Americans, although after adjusting for factors relating to socioeconomic status, any difference was consistent with chance . However, this did not fully explain all differences: despite adjustment, access to transplant was later and time to dialysis shorter for children of African American ethnicity. For Hispanic children in the USA, uninsured children and young adults were 43% less likely to be waitlisted at any given time than their uninsured White counterparts . In 2022, there are still no studies that have examined racial differences in timeliness and completion of the transplant evaluation process in children [20, 21]. In one study, the most common reasons for not being waitlisted were preparation for living donation and medical reasons for young children precluding eligibility, however others , including this study , have demonstrated that children of non-White ethnicity are less likely to receive living donor kidney transplants. Ultimately, however, it is at the discretion of the clinician to consider a child and their family ‘ready’ for waitlisting and transplantation, and therefore probable that unconscious biases relating to socioeconomic status and race may influence assessments of preparedness: a hypothetical study by Furth et al.  demonstrated that while race was not an independent factor in the decision for transplantation, it moderated the associations between compliance and parental education with decision for transplant, with higher odds for transplant referral for white compliant children and children of Black educated parents.
So how can we begin to ameliorate this situation? Firstly, we need to understand how each of the underlying processes from diagnosis to waitlisting contribute to the overall disparity seen. Secondly, we need to determine to what extent modifiable (parental activation/education, unconscious clinical bias) and non-modifiable (primary kidney disease, socioeconomic status) factors are mediating these disparities to be able to design complex, multifaceted, interventions which overcome or circumnavigate these. As the authors of this study suggest, such interventions could include streamlining of the transplant evaluation process to facilitate access and clinical training to prevent unconscious biases influencing waitlist decisions. Such interventions could also positively influence pre-emptive transplantation rates, which in this study were lower among Black and Hispanic children compared to white children . Alongside this, interventions to support Black and Hispanic families to identify and approach potential living kidney donors are needed to reduce differences in transplant access. Charnaya et al. have demonstrated that for Black and Hispanic children, we have made demonstrable gains in the risk of all-cause graft failure in the medium-term, but we are yet to demonstrate equity of access to waitlisting and pre-emptive transplant compared to White peers in the modern era. The journey to racial equity is very much unfinished and requires all of us to be proactive, informed, and cognizant of unconscious biases to ensure progress.
- All cause graft failure
- Chronic Kidney Disease in children (study)
- Calculated Panel Reactive Antibody
- Deceased donor kidney transplantation
- Donor Service Area
- Gross Domestic Product
- Kidney Allocation Scheme
- Kidney Donor Profile Index
- Kidney replacement therapy
- Organ Procurement and Transplantation Network
- Scientific Registry of Transplant Recipients
- USA :
- United States of America
- United States Renal Data System
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