CKD Progression From the Time of Estimated GFR-Based Waitlist Eligibility and Racial Disparities in Transplant Access

Abstract

Rationale & objective: Equations for estimated glomerular filtration rate (eGFR) that incorporate a term for race assign a higher value to Black individuals compared to non-Black individuals for the same sex, age, and serum creatinine concentration. This difference may contribute to racial disparities in kidney transplant access. We sought to (1) compare time from meeting a transplant eligibility threshold of eGFR ≤20 mL/min/1.73 m² to kidney failure with replacement therapy (KFRT) among Black, Hispanic, and White patients, and (2) assess the impact of incorporation of race into eGFR expressions on establishment of waitlist eligibility and time from eligibility to KFRT.

Study design: Retrospective cohort.

Setting & participants: Using the OptumLabs Data Warehouse, we assembled a cohort of 40,042 White, 8,519 Black, and 3,569 Hispanic patients having at least one eGFR value between 20 and 60 mL/min/1.73 m² within the preceding 2 years and an incident outpatient eGFR of ≤20 mL/min/1.73 m² between 2008-2018, using the CKD-EPI creatinine equation that includes a term for race coded as Black or non-Black. We then reassembled a Black patient cohort based on incident eGFR ≤20 mL/min/1.73 m² (n = 11,269) estimated using the same CKD-EPI equation but coding Black patients as non-Black.

Exposure: Race/ethnicity.

Outcome: Time to KFRT.

Analytical approach: Unadjusted and adjusted Fine-Gray models; linear regression to compute eGFR slopes.

Results: By 3 years, the cumulative incidence of KFRT was 20.5% among White patients, 40.9% among Hispanic patients, 36% among Black patients whose GFR was estimated using a race term coded as Black, and 28.7% among Black patients whose GFR was estimated using a race term coded as non-Black. In fully adjusted analyses including 11,269 Black patients with an eGFR ≤20 mL/min/1.73 m² based on coding them as non-Black, KFRT risk remained greater among Black (HR, 1.28 [95% CI, 1.15-1.43]) and Hispanic (HR, 1.66 [95% CI, 1.18-2.31]) patients than among White patients. Based on slopes of eGFR decline, coding Black patients as non-Black would allow earlier waitlist activation by an estimated median of 0.5 [interquartile range, 0.27-1.23] years.

Limitations: Inability to exclude individuals who would not be kidney transplant candidates if comprehensively evaluated.

Conclusions: A uniform eGFR threshold provides less opportunity for being placed on the transplant waitlist among Black and Hispanic patients. For many Black patients, estimation of GFR as if their race category were non-Black would allow substantially earlier waitlisting but would not eliminate their shorter time to KFRT and reduced opportunity for preemptive transplantation compared with White patients.

Keywords: CKD progression; Chronic kidney disease (CKD); eGFR equation; eGFR trajectory; end-stage renal disease (ESRD); estimated glomerular filtration rate (eGFR); kidney failure; kidney transplant; preemptive transplantation; racial disparities; transplant eligibility; waitlisting eligibility.