Impact of Race-Free Glomerular Filtration Rate Estimations on CKD Prevalence in the US Military Health System: A Retrospective Cohort Study

Abstract

Rationale & Objective: The 2021 CKD-EPI removes Black race as a factor in calculating the estimated glomerular filtration rate (eGFR). We assessed its effect on CKD prevalence in the demographically-diverse US Military Health System. Study Design: A retrospective calculation of the eGFR from serum creatinine measured over 2016-2019 using both the 2009 and 2021 CKD-EPI equations. Setting & Population: Multicenter health care network with data from 1,502,607 adults in the complete case analysis and from 1,970,433 adults in an imputed race analysis. Predictors: Serum creatinine, age, sex, and race. Outcome: CKD stages 3-5, defined as the last eGFR persistently < 60 mL/min/1.73m2 for ≥90 days. Analytical Approach: The t test and Kruskal-Wallis test were used for continuous variables and Χ2 for categorical data. Results: The population in the complete case analysis had a median age of 40 years and was 18.8% Black race and 35.4% female. With the 2021 equation, the number of Black adults with CKD stages 3-5 increased by 58.1% from 4,147 to 6,556, a change in the crude prevalence from 1.47% to 2.32%. The number of non-Black adults with CKD stages 3-5 decreased by 30.4% from 27,596 to 19,213, a crude prevalence change from 2.26% to 1.58%. Similar results were seen with race imputation. Cumulatively, among adults with CKD stages 3-5 by at least one equation, 45.8% of Black adults were reclassified to more advanced stages of CKD and 44.0% of non-Black adults were reclassified to less severe stages across eGFR thresholds that could change clinical management. Limitations: Potential underestimation of CKD in individuals with only 1 measurement. Conclusions: Adoption of the 2021 CKD-EPI equation in the Military Health System reclassifies many Black adults into new CKD stages 3-5 or into more advanced CKD stages, with the opposite effect on non-Black adults. This may have an effect on CKD treatment and outcomes in ways that are yet unknown. Plain-Language Summary: Until recently, kidney function level was calculated from equations that adjusted the result if the individual was of Black race. Because this may contribute to racial disparities in kidney disease care, a new equation was developed in 2021 that excludes race as a factor. We assessed the possible effects of this equation using data from adults in the US Military Health System from 2016 to 2019. With the new equation, the number of Black adults classified with kidney disease increased while that of non-Black adults decreased. There were similar trends seen in the more severe levels of kidney disease, which could affect decisions in clinical care. These results emphasize the potential positive and negative outcomes to be monitored with the new equation.

Keywords

• Estimated glomerular filtration rate
• chronic kidney disease
• racial disparities in health care
• Military Health System