Racial Differences in Estimated GFR Decline, ESRD, and Mortality in an Integrated Health System

Background: Current evidence does not clearly identify the contribution of kidney function decline and mortality to racial disparities in end-stage renal disease (ESRD) incidence. We used observed estimated glomerular filtration rate (eGFR) to project the time of onset of kidney failure and examined mortality to better understand these racial disparities. Study Design: Retrospective cohort. Setting & Participants: Adult members of Kaiser Permanente Southern California in 2003-2009 with more than 2 serum creatinine tests and more than 180 days between tests: 526,498 whites, 350,919 Hispanics, 136,923 blacks, and 105,476 Asians. Predictor: Race/ethnicity. Outcomes: ESRD (dialysis or transplantation); mortality. Measurements: eGFR decline was modeled using linear regression. Kidney failure was projected based on predicted eGFR <15 mL/min/1.73 m(2) at specified times. Racial differences in projected kidney failure and mortality in those with projected kidney failure were estimated with adjustment for age, sex, and entry eGFR. Results: Blacks had more extreme rates of eGFR decline (1st percentile, -23.6 mL/min/1.73 m(2) per year), followed by Hispanics (-20.9 mL/min/1.73 m2 per year), whites (-20.1 mL/min/1.73 m2 per year), and Asians (-17.6 mL/min/1.73 m2 per year; P < 0.001). There were 25,065 whites, 11,368 Hispanics, 6,785 blacks, and 3,176 Asians with projected kidney failure during the study period. The ORs for projected kidney failure versus whites during CKD stages 3 and 4 were 1.54 (95% CI, 1.46-1.62) in blacks, 1.49 (95% CI, 1.42-1.56) in Hispanics, and 1.41 (95% CI, 1.32-1.51) in Asians. For those with projected kidney failure, the HRs of death versus whites during CKD stages 3 and 4 were 0.82 (95% CI, 0.77-0.88) in blacks, 0.67 (95% CI, 0.63-0.72) in Hispanics, and 0.58 (95% CI, 0.52-0.65) in Asians. Limitations: Results may not generalize to the uninsured or subgroups within a race. Projected kidney failure was based on linear trends from clinically obtained eGFR. Conclusions: We found more extreme rates of eGFR decline in blacks. Projected kidney failure during CKD stages 3 and 4 was high in blacks, Hispanics, and Asians relative to whites. Mortality for those with projected kidney failure was highest in whites. Differences in eGFR decline and mortality contributed to racial disparities in ESRD incidence.