Pediatric kidney transplant disparities

Abstract

BACKGROUND

Kidney transplantation (KT) is essential for end-stage renal disease, significantly improving survival and quality of life. Yet, in pediatric renal disease management, minority children face poorer dialysis outcomes and reduced access to transplantation.

AIM

To identify and understand these differences in the pediatric population.

METHODS

Using ICD-10 codes, we queried the 2022 Health Care Cost and Use Project Kid’s Inpatient Database for admissions with a primary or secondary diagnosis of severe chronic kidney disease (sCKD), namely stages 4 and 5, or a KT procedure. Patient demographics, insurance types, and hospital stay metrics were assessed through statistical analyses including Wilcoxon Rank Sum, χ², and logistic regression.

RESULTS

A total of 636 hospital admissions related to KT surgery and 3733 hospital admissions with sCKD as the primary diagnosis were identified. In both the KT and sCKD cohorts, most patients were White (42.6% vs 36.6%), male (59.8% in both groups), aged 12-18 years (57.9% vs 50.3%), and insured by Medicaid (35.7% vs 43.0%). KT and sCKD hospitalizations were uncommon among infants aged 0-1 year (1.6% and 9.9%, respectively). Analysis of income quartiles based on patients’ residential zip codes demonstrated no significant differences between those who underwent KT and those with sCKD without transplant. Although mortality rates did not differ statistically between groups, a numerical difference was observed, with higher mortality in the sCKD cohort compared to the KT cohort (16 deaths vs 4 deaths).

After adjusting for socioeconomic and geographic factors, Black race was independently associated with lower odds of undergoing KT (adjusted odds ratio 0.69; 95% confidence interval: 0.53-0.89).

CONCLUSION

Pediatric KT recipients were more likely to be male, White, and aged 12-18 years. Racial disparities persist, with ethnic minority groups-particularly Black patients-facing reduced access to KT. These findings underscore the necessity of implementing targeted interventions to promote equitable access to pediatric KT.

Key Words: Kidney transplant; Severe chronic kidney disease; Pediatric; Socio economic disparities; Transplant allocation

Core Tip: In this study, we found that black race is significantly associated with lower rates of kidney transplantation (KT) after controlling socioeconomic and geographic factors. Although studies have analyzed health care utilization and disparities in various pediatric renal diseases such as acute kidney injury, socioeconomic and demographic disparities have been poorly defined in the pediatric literature on KT. In this study, we excluded young adults 18-21 who may have increased difficulty with access to care as they transition from pediatric to adult care. Future prospective studies are needed to evaluate the complexity of disparities in pediatric KT access.

INTRODUCTION

Nearly 10000 children and adolescents in the United States are living with end-stage renal disease (ESRD). The etiologies of ESRD in this population include renal dysplasia, obstructive uropathy, nephrotic syndrome, polycystic kidney disease, familial nephritis, and other congenital and acquired kidney disorders. Hospital utilization associated with nephrotic syndrome has previously been evaluated using the Healthcare Cost and Utilization Project Kids’ Inpatient Database (HCUP-KID). In 2006 and 2009, nephrotic syndrome accounted for an estimated 48700 inpatient days, with total hospital charges reaching $259 million[1]. These findings underscore the substantial hospitalization burden associated with pediatric kidney disease.

Prior studies have demonstrated disparities in the treatment of pediatric patients with acute kidney injury (AKI). Uninsured children and those from minority populations are more likely to develop AKI[2], and Asian American, Hispanic, and African American children have been shown to have a higher risk compared with White children. Additionally, access to renal replacement therapy (RRT), including hemodialysis and peritoneal dialysis, is characterized by racial and ethnic disparities[3]. Several studies have also identified disparities in pediatric transplant waitlist access, as well as in receipt of deceased donor kidney transplantation (KT) and living donor KT[4].

Children with ESRD are at increased risk for complications such as anemia, cardiovascular disease, and bone disorders. Although many patients receive RRT, KT remains the optimal treatment for long-term survival and quality of life. However, pediatric healthcare utilization has not been previously examined in a large dataset to simultaneously evaluate severe chronic kidney disease (sCKD) and KT across demographic groups. In this study, we sought to characterize differences in healthcare utilization and costs among pediatric patients undergoing KT compared with those hospitalized with sCKD.

MATERIALS AND METHODS

Study design and setting

A retrospective study was conducted using the HCUP-KID, a database supported by the Agency for Healthcare Research and Quality and is the largest all-payer pediatric inpatient care database in the United States. Data is publicly available, de-identified personal health information, and thus Institutional Review Board exempt. We queried the 2022 Kid’s Inpatient Database (KID) for admissions with a primary or secondary diagnosis of sCKD, namely stages 4 and 5, or a KT.

Patient selection

Using ICD-10 codes, we queried the 2022 Health Care Cost and Use Project KID for admissions with a primary or secondary diagnosis of sCKD and end stage renal disease (ESRD), namely stages 4 and 5 [N18.4; N18.5; N18.6], or a KT procedure[Z94]. Patient demographics, insurance types, and hospital stay metrics were assessed through statistical analyses including Wilcoxon Rank Sum, χ², and logistic regression.

All admitted children in the KID aged 1-18 years on admission were included. Children under the age of 1 were not included because the database only provided age in years. Chronic kidney disease is classified by stages based of eGFR. We defined sCKD as stages 4 (eGFR 1529) and 5 (eGFR < 15). ICD-10 codes were utilized to identify the degree of kidney impairment on admission. Our primary outcome was mortality with and without KT.

Other variables analyzed included patient demographics (age, sex, and race), Glasgow Coma Scale, length of stay, income quartiles, and insurance type. Patient demographics and clinical outcomes were compared by whether they received a KT and had sCKD.

Statistical analysis

Descriptive statistics summarized the demographic, clinical, and outcome variables. The distribution of continuous variables using the Kolmogorov-Smirnov test were assessed, and due to their non-parametric nature, analyses utilized medians and interquartile ranges. Univariate analysis involved comparing continuous variables between stratified groups using the Mann Whitney U test, while categorical variables were analyzed with χ² tests and Fischer’s exact test when appropriate. Odds ratios (OR) were calculated to determine the strength of associations between identified predictors and the outcome, specifically odds of receiving a KT. Percentages of descriptive statistics may not sum to 100% due to the presence of missing not applicable data; however, missing data for most variables was minimal (< 5%) and thus excluded in the final analysis. Further univariate and multivariate analyses were conducted only on complete data. Statistical significance was established at a P value of less than 0.05. Data analysis was performed using R-studio version 2023.12.0+369.

RESULTS

A total of 636 hospital admissions related to KT surgery and 3733 hospital admissions with sCKD as the primary diagnosis were identified. In both cohorts, the majority of patients were White (42.6% vs 36.6%), male (59.8% in both groups), aged 12-18 years (57.9% vs 50.3%), and insured by Medicaid (35.7% vs 43.0%). Hospitalizations for KT and sCKD were uncommon among infants aged 0-1 year (1.6% and 9.9%, respectively). Both sCKD and KT hospitalizations were most frequently reported in hospitals located in the Southern region within the HCUP-KID database.

Analysis of income quartiles based on patients’ residential zip codes demonstrated no significant differences between those who underwent KT and those with sCKD without transplantation. A proportionately higher number of patients with sCKD and those with commercial insurance underwent KT compared with patients insured through Medicare or Medicaid. Although mortality rates did not differ statistically between the KT and sCKD groups, a numerical difference was observed, with higher mortality in the sCKD cohort (16 deaths vs 4 deaths). After adjustment for socioeconomic and geographic factors, Black race was independently associated with lower odds of undergoing KT (adjusted OR 0.69; 95% confidence interval: 0.53-0.89) (Table 1).

Table 1 Demographics and characteristics of admissions by performance of kidney transplantation, n (%) or median (IQR).

Total discharges	Kidney transplant	Severe CKD	Univariate		Multivariate
			P value	OR	95%CI lower	95%CI upper	P value
Unweighted	636	3733
Weighted	859	5038
Age, years			< 0.001b
0-1	10 (1.6)	371 (9.9)		1
2-5	105 (24.1)	593 (15.9)		7.76	3.96	17.57	< 0.0001b
6-11	153 (24.1)	893 (23.9)		7.50	3.87	16.83	< 0.0001b
12-18	368 (57.9)	1876 (50.3)		8.87	4.65	19.72	< 0.0001b
Sex			1.0
Male	380 (59.8)	2234 (59.8)		1
Female	256 (40.3)	1499 (40.2)		0.995	0.83	1.19	0.96
Race			< 0.05a
White	271 (42.6)	1365 (36.6)		1
Black	102 (16.0)	784 (21.0)		0.69	0.53	0.89	0.01a
Hispanic	181 (28.5)	1012 (27.1)		0.92	0.73	1.15	0.44
Asian/Pacific Islander	20 (3.1)	144 (3.9)		0.69	0.41	1.10	0.14
Native American	10 (1.6)	44 (1.2)		1.29	0.57	2.62	0.50
Other	24 (3.8)	195 (5.2)		0.70	0.43	1.08	0.12
Zip code income quartile			< 0.05a
Lowest	179 (28.1)	1220 (32.7)		1
Second	141 (22.2)	907 (24.3)		0.99	0.77	1.27	0.94
Third	179 (28.1)	870 (23.3)		1.22	0.95	1.55	0.12
Highest	130 (20.4)	672 (18.0)		1.13	0.86	1.49	0.37
Hospital region			< 0.05a
Northeast	102 (16.0)	553 (14.8)		1
Midwest	143 (22.5)	724 (19.4)		1.13	0.84	1.52	0.41
South	215 (33.8)	1498 (40.1)		0.85	0.65	1.12	0.24
West	176 (27.7)	958 (25.7)		0.88	0.67	1.18	0.40
Primary payer			< 0.001b
Medicare	131 (20.6)	868 (23.3)		1
Medicaid	227 (35.7)	1607 (43.0)		0.95	0.75	1.22	0.69
Private insurance	208 (32.7)	1025 (27.5)		1.18	0.92	1.53	0.20
Self-pay	20 (3.1)	43 (1.2)		4.06	2.13	7.60	< 0.0001b
No charge	0 (0)	2 (0.1)		NA	NA	NA
Other	50 (7.9)	180 (4.8)		1.95	1.30	2.88	0.001a
Mortality	4 (0.6)	16 (0.4)	0.71
Total charges, $	303106 (187057)	38429.5 (60987.5)	< 0.001b
Length of stay, days 9[5] 3[4]			< 0.001b

^aP < 0.05.

^bP < 0.001.

P values are the result of univariate analysis (χ² or Fischer test for categorical data, and Wilcoxon rank sum test for continuous non-parametric data) and of multivariate logistic regression analysis. CKD: Chronic kidney disease; OR: Odds ratio; CI: Confidence interval.

DISCUSSION

In this study, Black race was independently associated with lower odds of KT after adjustment for geographic and socioeconomic factors. These findings align with prior literature demonstrating disparities in pediatric renal disease care. Previous studies have identified racial and socioeconomic differences in AKI, dialysis outcomes, and transplant access[5,6]. Others have focused on pediatric specific pathology that is associated with ESRD such as upper tract staghorn calculi and nephrotic syndrome[7,8]. Bjornstad et al[2] reported that uninsured children were more likely to develop AKI compared with insured children, estimating that one episode of AKI could potentially be prevented for every 70 hospitalized uninsured children if Medicaid coverage were provided[7]. Similarly, Laster et al[5] found worse survival among African American pediatric dialysis patients.

Disparities in transplantation are complex. Suitability for KT may vary based on graft–recipient size matching and genetic etiologies of kidney disease, which can differ across racial and ethnic groups[9]. Additionally, several studies have reported poorer post-transplant outcomes among minority populations[10,11]. Amaral et al[6] demonstrated that racial disparities were more pronounced in access to living donor transplantation compared with deceased donor transplantation and persisted even after adjusting for insurance status and neighborhood poverty. These findings suggest that structural and systemic inequities, including differential access to care, are likely contributors[12].

In our analysis of the HCUP-KID dataset, White patients underwent transplantation at rates higher than their proportional representation among sCKD hospitalizations, whereas the reverse pattern was observed among Black patients. Although mortality differences between KT and sCKD hospitalizations were not statistically significant, numerically higher mortality was observed among patients hospitalized with sCKD, who were more likely to be from minority populations. Adult transplant access studies have clearly demonstrated impaired transplant access in Hispanic and Non-Hispanic Black individuals as compared to Caucasians[13]. Prior studies have consistently demonstrated superior long-term survival with KT compared to prolonged dialysis[14,15], suggesting that disparities in transplant access may have meaningful clinical implications.

The transplant process involves multiple steps, including referral, evaluation, waitlisting, and donor availability. Patzer et al[7] showed that, after adjusting for socioeconomic factors, Black children were 10% less likely to progress from incident ESRD to deceased donor transplantation. Because HCUP-KID captures hospitalization-level data rather than longitudinal patient trajectories, our study cannot determine at which stage disparities arise. Thus, extrapolating inpatient demographic patterns directly to transplant access represents a limitation. Nonetheless, these data provide an important national snapshot highlighting inequity in care delivery.

Insurance status also appeared to influence transplant patterns[16]. Patients with commercial insurance had a proportionately higher rate of KT relative to sCKD hospitalizations, whereas Medicare and Medicaid groups had proportionately more sCKD hospitalizations. While insurance coverage-commercial or governmental-is generally required to obtain transplantation in the United States, differences in coverage type may reflect broader socioeconomic disparities affecting referral patterns, evaluation completion, and access to living donors. The small self-pay cohort limits interpretation, as this group may include both affluent families and those experiencing temporary coverage gaps.

Consistent with prior work, pediatric CKD hospitalizations are associated with increased healthcare utilization and cost[17]. Although KT hospitalizations demonstrated higher single-admission costs-likely reflecting surgical complexity-our analysis does not capture longitudinal outpatient dialysis costs or cumulative healthcare utilization. Therefore, comparing single hospitalizations between KT and sCKD does not fully reflect the long-term economic implications of treatment strategies.

This study has several limitations. HCUP-KID includes only inpatient data and lacks outpatient, longitudinal, and granular social determinants of health variables. The retrospective design limits causal inference. Young adults aged 18-21 years were excluded, although this transition period is known to present barriers to care. Additionally, infants under 1 year of age are underrepresented, despite being a vulnerable population.

Future research should include prospective, multi-institutional studies incorporating outpatient utilization, social environment variables, family preferences, and structural determinants of health. Such designs would allow more precise identification of where disparities arise and inform targeted interventions. Patient navigation programs, expanded social work support, and policy-level strategies may help mitigate inequities, as demonstrated in other disease models. The 2014 implementation of the Kidney Allocation System was associated with improvements in equity for time to transplantation and short-term graft outcomes[18], suggesting that system-level reforms can reduce disparities.

Overall, our findings add to the growing body of literature demonstrating persistent racial and socioeconomic disparities in pediatric KT and underscore the need for national, structural interventions to promote equitable access to high-quality donor organs.

CONCLUSION

In 2022, an estimated 636 pediatric KT hospitalizations were identified in the United States. Pediatric KT recipients were more likely to be male, White, and aged 12-18 years. Despite comparable representation of White and non-White patients among sCKD hospitalizations, Black patients had significantly lower odds of undergoing KT. These findings highlight persistent racial disparities and emphasize the need for targeted, system-level interventions to ensure equitable access to pediatric KT.