Segregation Affects Living Donor Kidney Transplantation Access

With shorter wait times and better patient and graft survival, living donor kidney transplantation (LDKT) is the preferred method of kidney replacement therapy. However, the rate of LDKT is 4.3 times lower for Black patients than White patients, although Black individuals have a 3.8 times higher rate of end-stage kidney disease (ESKD). It is clear structural racism is at play, but examinations into the specifics of these disparities are lacking.

A group of researchers led by Yiting Li, MPH, looked at the problem from the perspective of segregation based on individuals’ race or ethnicity. In a national cohort study of transplant candidates, the team researched the association between a candidate’s access to LDKT and their residential neighborhood segregation and their transplant center’s neighborhood segregation. The study results appear in JAMA Internal Medicine.

The study population included adults who were candidates for first-time kidney transplant (KT), including nonlisted patients who had LDKT between 1995 and 2021. These individuals were categorized by race and ethnicity as either non-Hispanic/Latino Black (Black) or non-Hispanic White (White). The categories were based on variables provided on Organ Procurement and Transplantation Network forms, and researchers obtained data from the Scientific Registry of Transplant Recipients. Race-specific population counts at the zip code level came from American Community Survey 5-year estimates from the US Census Bureau.

Researchers used the Theil H method to measure segregation tertiles in zip code tabulation areas. They used the Kaplan-Meier method to estimate the unadjusted aggregate incidence of the first LDKT by candidate race and tertiles of their neighborhood of residence and the transplant center’s neighborhood segregation. Then they used the cause-specific hazards models to determine the likelihood of LDKT by tertiles of residential neighborhood and transplant center neighborhood segregation.

The researchers calculated the association of the residential neighborhoods’ and transplant centers’ neighborhood segregation by race and tested for trends over time. They confirmed the proportional hazards assumption using complementary log-log plots and Schoenfeld residuals, then looked at within-group differences in high-segregation neighborhoods, comparing mainly White neighborhoods (≥70% White) with multiracial neighborhoods (31%-69% White) and mostly minority neighborhoods (≤30% White), testing whether these associations differed by the patient’s race. To validate the findings, the researchers used the Index of Concentration at Extremes–Race-Income measure as an alternative for segregation. Then they determined the strength of the estimates through various sensitivity analyses.

Among 162,587 candidates for KT, the mean (SD) age was 51.6 (13.2) years; 65,141 (40.1%) were female; and 80,023 (49.2%) were Black. Black transplant candidates residing in high-segregation neighborhoods had 10% (adjusted hazard ratio [aHR], 0.90; 95% CI, 0.84-0.97) lower access to LDKT compared with Black candidates living in low-segregation neighborhoods. This association was not present among White candidates (P=.01). High-segregation residential neighborhoods had a higher proportion of Black candidates relative to low-segregation residential neighborhoods. High-segregation residential neighborhoods had 69.2% Black candidates; medium-segregation neighborhoods, 47.2%; and low-segregation neighborhoods, 30.2% (P<.001).

Both Black (aHR, 0.94; 95% CI, 0.89-1.00) and White (aHR, 0.92; 95% CI, 0.88-0.97) patients at transplant centers in high-segregation neighborhoods had lower access to LDKT than those in low-segregation neighborhoods (P=.64). Of candidates listed at transplant centers in high-segregation neighborhoods, a greater proportion were Black (high-segregation, 62.7%; medium-segregation, 45.8%; low-segregation, 37.5%; P<.001).

In high-segregation transplant center neighborhoods, candidates listed at centers in mostly minority neighborhoods had 17% lower access to LDKT compared with candidates listed at centers in mostly White neighborhoods (aHR, 0.83; 95% CI, 0.75-0.92). Black candidates living in or listed at transplant centers in mostly minority neighborhoods had a 64% lower likelihood of LDKT compared with White candidates living in or listed at transplant centers located in majority White neighborhoods.

Limitations of the study included using zip codes, which may include diverse neighborhoods, as proxies for neighborhoods. This could result in spatial misclassification and modifiable areal unit problems that could cause systematic biases in the researchers’ analysis. In addition, some race and ethnicity variables from the national registry were clinician-reported, which could result in misclassification bias. Lastly, using aggregated demographic information to define segregation may not completely capture the multidimensional aspects of structural racism in a neighborhood; future studies should consider other ways to measure structural racism.

“This national cohort study highlights the considerable role of racial and ethnic segregation in both the candidate’s residential neighborhood and the transplant center’s neighborhood in shaping access to LDKT,” the authors said. They concluded that, “To promote equitable access, studies should assess targeted interventions (eg, community outreach clinics) to improve support for potential candidates and donors and ultimately mitigate the effects of segregation.”

Source: JAMA Internal Medicine