Center-Level Factors and Racial Inequity in Living Donor Kidney Transplant

The rate of new cases of kidney failure in Black patients is double that in White patients. Patients with kidney failure who receive living donor kidney transplant experience improved quality of live and excellent long-term graft survival. It is well established that, despite policy- and research-associated interventions, racial disparities in living donor kidney transplant persist.

According to Lisa M. McElroy, MD, MS, there are few data available on associations between transplant center-specific characteristics and catchment area population characteristics and living donor kidney transplant racial inequities. To identify targets for multilevel interventions, the researchers conducted a study to examine racial differences in rates of living donor kidney transplant relative to differences in waiting list, referral region, and center characteristics. Results were reported in JAMA Network Open.

The retrospective cohort longitudinal study was completed in February 2023. The cohort included transplant centers in the United States with at least 12 annual living donor kidney transplants from January 1, 2008, to December 31, 2018. The centers were identified using the Health Resources Services Administration database linked to the US Renal Data System and the Scientific Registry of Transplant Recipients.

The primary outcome of interest was center yearly living donor kidney transplant rate ratio (RR) between Black and White individuals. The researchers calculated the rate of living donor kidney transplant per eligible wait time for Black and White patients for each center in each year, then derived the ratio of those rates as the living donor kidney transplant RR between Black and White individuals. An RR of 1 indicated equal rate (racial equality) and lower than 1 indicated inequity for Black patients.

Modifiable and nonmodifiable covariates were derived at three levels: transplant referral region where the centers were located, center characteristics, and characteristics of the waitlisted patients. Nonmodifiable covariates included characteristics of patients waitlisted for kidney transplant and transplant referral region population. Characteristics of waitlisted patients included percentage female sex, calculated panel reactive antibody greater than 70%, less than postsecondary education, and type B blood. Transplant referral region characteristics included Black population prevalence, percentage uninsured, and interquintile range of the Area Deprivation Index.

Modifiable covariates at the center level included participation in the National Kidney Registry voucher or paired exchange programs, state Medicaid expansion, and percentage of total kidney transplants that were living donor transplants. Medicaid expansion was used as a proxy for care to the uninsured.

The final cohorts used to derive the living donor kidney transplant rate outcome included 394,625 adults who were waitlisted, of whom 33.1% were Black and 66.9% were White, and 57,222 adult living donor kidney transplant recipients, of whom 14.1% were Black and 85.9% were White. There were no additional racial or ethnic categories included in the study

There was an association between the prevalences of Black populations within a geographic transplant referral region and overall volume of living donor kidney transplants. Over time, there was a concave trend in the percentage of living donor kidney transplants that were United Network for Organ Sharing Kidney Paired Donation Program-matched runs.

During the study period, center-level living donor kidney transplant RRs between Black and White individuals ranged from 0.00 to 4.27. Among the 89 transplant centers included in the study, yearly medians ranged from 0.197 in 2015 to 0.305 in 2010. Those results indicated median lower rates of living donor kidney transplant among Black patients compared with White patients. When the estimation model included patient, center, and regional characteristics, estimated center-level RRs over the entire study period ranged from 0.577 to 0.771, and yearly medians of center RRs ranged from 0.216 in 2016 to 0.285 in 2010.

Across all centers, all study period years, and all levels of categorical variates, with numeric covariates fixed at observed mean values, the estimated average living donor kidney transplant RR between Black and White individuals was 0.260 (95% CI, 0.227-0.298), indicating that, on average, racial equity in living donor kidney transplant rates was not achieved at these centers. More specifically, Black patients experienced inequity.

In the hypothetical best-case scenario, model-based estimations resulted in little change in the minimum RR (from 0.0557 to 0.0559), but a greater positive shift in the maximum from 0.771 to 0.895. Relative to the observed 582 living donor kidney transplants in Black patients and 3837 in White patients, the 2018 hypothetical model estimated an increase of 423 living kidney donor transplants in Black patients (a 72.7% increase) and of 1838 living donor kidney transplants for White patients (a 47.9% increase).

There were some limitations to the study cited by the authors, including the use of national data registries, the discordant dates available for the transplant referral region-level covariate sources, and the derivation of the transplant referral regions based on hospital referral regions. In addition, the cohort design prevented the establishment of causality.

In conclusion, the researchers said, “The findings of this cohort study suggest that racial inequities in living donor kidney transplant persist despite decades of investigation and intervention. Our findings observed geographic but no temporal variation and suggest that center participation in national programs, such as the paired exchange and voucher programs, may help to mitigate living donor kidney transplant Black-White race inequities. Overall, our findings support the increasingly accepted notion that a strong program is multifactorial and many contributing factors remain unmeasured by national data systems. Achieving racial equity will require identification of living donor kidney transplant RRs related to the referral region conditions, and tailored interventions and goalsetting should be  based on the center-specific barriers to achieve them.”

Source: JAMA Network Open