Estimating time to ESRD using kidney failure risk equations: Results from the African American Study of Kidney Disease and Hypertension (AASK)

Background Planning for renal replacement therapy, such as referral for arteriovenous fistula placement and transplantation, often is guided by level of estimated glomerular filtration rate (eGFR). The use of risk equations might enable more accurate estimation of time to end-stage renal disease (ESRD), thus improving patient care. Study Design Prospective observational study. Setting & Participants 1,094 participants in the African American Study of Kidney Disease and Hypertension (AASK) cohort. Predictor Age, sex, urine protein-creatinine ratio ≥ 1 g/g, APOL1 high-risk status, and 3-year antecedent eGFR decline. Outcome Cumulative incidence of ESRD from 5 different starting points: eGFR of 30 and 15 mL/min/1.73 m² and 1-year ESRD risk of 5%, 10%, and 20%, estimated by a published 4-variable kidney failure risk equation. Results 566 participants developed eGFR of 30 mL/min/1.73 m², 244 developed eGFR of 15 mL/min/1.73 m², and 437, 336, and 259 developed 1-year ESRD risks of 5%, 10%, and 20%, respectively. The 1-year cumulative incidence of ESRD was 4.3% from eGFR of 30 mL/min/1.73 m², 49.0% from eGFR of 15 mL/min/1.73 m², 6.7% from 5% ESRD risk, 15.0% from 10% ESRD risk, and 29% from 20% ESRD risk. From eGFR of 30 mL/min/1.73 m², there were several risk factors that predicted ESRD risk. From eGFR of 15 mL/min/1.73 m², only level of proteinuria did; median time to ESRD was 9 and 19 months in those with higher and lower proteinuria, respectively. Median times were less variable from corresponding ESRD risk thresholds. For example, median times to ESRD from 20% ESRD risk were 22 and 25 months among those with higher and lower proteinuria, respectively. Limitations Relatively homogeneous population of African Americans with hypertensive kidney disease. Conclusions Results of the present study suggest the potential benefit of incorporating kidney failure risk equations into clinical care, with selection of a specific threshold guided by its intended use.