Ethnic Disparities in Chronic Kidney Disease Progression: A Comparative Study of CRIC and KNOW-CKD Cohorts.

Background: Ethnic differences in chronic kidney disease (CKD) progression remain understudied, particularly between Asian and Western populations. Therefore, we aimed to investigate ethnic disparities in CKD progression by comparing nationwide cohorts from South Korea (the Korean cohort study for Outcomes in Patients With CKD [KNOW-CKD]) and the United States (the US Chronic Renal Insufficiency Cohort [CRIC]). Methods: A total of 4,953 participants were included (69% from CRIC and 31% from KNOW-CKD). The primary outcome was CKD progression, defined as a 50% or greater decline of estimated glomerular filtration rate (eGFR) or kidney failure requiring kidney replacement therapy. In the secondary outcome analysis, we compared eGFR decline rates and all-cause mortality. Results: Of the 4,953 participants, CKD progression occurred in 1,285 and 570 in the KNOW-CKD and CRIC cohorts, with incidence rates of 67.9 and 41.7 per 1,000 person-years, respectively. The hazard ratio for the KNOW-CKD compared to CRIC was 1.66 (95% confidence interval [CI], 1.45–1.89). The annual eGFR decline was steeper in KNOW-CKD participants than in CRIC participants (–2.51 vs. –1.14 mL/min/1.73 m 2 ). Asian participants from the CRIC cohort exhibited a similar eGFR slope (95% CIs) (–2.10 [–2.69 to –1.52]) to those from KNOW-CKD (–2.50 [–2.67 to –1.52]), while the slope was –1.47 (–1.61 to –1.33), and –0.81 (–0.92 to –0.70) mL/min/1.73 m 2 per year for Black and White participants, respectively. However, the risk of mortality was significantly lower in KNOW-CKD participants compared with CRIC participants (hazard ratio, 0.51; 95% CI, 0.38–0.68). Conclusions: CKD progression was faster in the Korean cohort than in the US cohort, with Asian participants in both cohorts showing similar eGFR decline rates. However, the Korean cohort had a lower risk of mortality, indicating potential ethnic or regional differences in disease progression and survival.