Effects of changes in calculating GFR using KDIGO standards: Discordance in the Staging and Timing of Diagnosis of Chronic Kidney Disease

IntroductionChronic kidney disease (CKD) is a highly prevalent disease with disparities in diagnosis and treatment. Until recently, primary diagnosis for CKD was based on equations that incorporated race and have demonstrated racial bias. This study had two aims comparing outcomes for Black patients and their counterparts: 1) whether using the new 2021 CKD-EPI equation led to decreased disparity with time to diagnosis; and 2) whether there was discordance in the staging between the two equations at potential diagnosis point. MethodsWe evaluated patients aged 18 and over with non-hospitalization related serum creatinine laboratory results between January 1, 2016 and September 30, 2023. We estimated the GFR for each patient using the 2009 and 2021 CKD-EPI creatinine equations. We assessed stage discordance for stages 3a, 3b, 4, and 5 using chi-square tests and the Cochran-Mantel-Haenszel. We used multivariate logistic regression to assess a change in staging based on the equation used. Results15.5% of the 8,080,889 patients included in this study were Black. The median age was 57 years and 15.3% of patients met the criteria for stage 3a CKD or higher using either equation. Discordance in staging by equation and by race existed, especially for Black patients at stages 3a and 3b. 40% of Black patients identified as stage 4 using the 2021 equation were 3b or lower using the 2009 equation. DiscussionWell established medical algorithms with race components are being re-examined. We found more disparity with the initial staging of the disease. The disconnect in the timing of staging by equation for Black patients means a number of these patients may not have received the appropriate treatment. Future work should elucidate the impact of the change in CKD staging with the 2021 CKD-EPI creatinine equation on treatment. ConclusionSignificant disparity exists in the timing and staging of CKD by CKD-EPI equation and by race.