Race-free renal function estimation equations and potential impact on Black patients: Implications for cancer clinical trial enrollment

Abstract

Background: Black patients face disparities in cancer outcomes. Additionally, Black patients are more likely to be undertreated and underrepresented in clinical trials. The recent recommendation to remove race from the estimated glomerular filtration rate (eGFR) results in lower eGFR values for Black patients. The ramifications of this decision, both intended and unintended, are still being elucidated in the medical community. Here, the authors analyze the removal of race from eGFR for Black patients with cancer, specifically with respect to clinical trial eligibility.

Methods: In a cohort of self-identified Black patients who underwent nephrectomy at a tertiary referral center from 2009 to 2021 (n = 459), eGFR was calculated with and without race in commonly used equations (Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI] and Modification of Diet in Renal Disease [MDRD]). The distribution of patients and changes within chronic kidney disease stages with different equations was considered. Theoretical exclusion at commonly observed clinical trial eGFR points was then simulated on the basis of the utilization of the race coefficient.

Results: The median eGFR from CKD-EPI was significantly higher with race (76 ml/min/1.73 m² ) than without race (66 ml/min/1.73 m² ; p < .0001). The median eGFR from MDRD was significantly higher with race (71.0 ml/min/1.73 m² ) than without race (58 ml/min/1.73 m² ; p < .0001). Observing results in the context of common clinical trial cutoff points, the authors found that 13%-22%, 6%-12%, and 2%-3% more Black patients would fall under common clinical trial cutoffs of 60, 45, and 30 ml/min, respectively, depending on the equation used. A subanalysis of stage III-IV patients only was similar.

Conclusions: Race-free renal function equations may inadvertently result in increased exclusion of Black patients from clinical trials. This is especially concerning because of the underrepresentation and undertreatment that Black patients already experience.

Plain language summary: Black patients experience worse oncologic outcomes and are underrepresented in clinical trials. Kidney function, as estimated by glomerular filtration rate equations, is a factor in who can and cannot be in a clinical trial. Race is a variable in some of these equations. For Black patients, removing race from these equations leads to the calculation of lower kidney function. Lower estimated kidney function may result in more black patients being excluded from clinical trials. The inclusion of all races in clinical trials is important for offering best care to everyone and for making results from clinical trials applicable to everyone.

Keywords: cancer disparities; clinical trials; glomerular filtration rate; health disparities; racial disparities; underrepresentation.