Patterns of Kidney Function Decline Associated with APOL1 Genotypes: Results from AASK.

Background and Objectives: Trajectories of eGFR in patients with CKD are highly variable. Only a subset of patients with CKD experiences a steady decline in eGFR. The objective of our study was to investigate whether eGFR trajectory patterns differ by APOL1 risk status.
Design, Setting, Participants, & Measurements: Our study was a longitudinal observational study of 622 participants in the African American Study of Kidney Disease and Hypertension with APOL1 genotyping and sufficient follow-up for estimating GFR trajectories. The predictor was APOL1 high-risk status (having two copies of the G1 or G2 risk alleles) versus low-risk status (zero or one copy of the risk alleles), and the outcome was four eGFR trajectory patterns on the basis of the joint probabilities of linearity and progression: steady decline, unsteady decline, steady stable, and unsteady stable.
Results: Over a median follow-up of 9 years, 24.0% of participants experienced steady eGFR decline, 25.9% had an unsteady decline, 25.6% were steady and stable, and 24.6% were unsteady but stable. Those experiencing steady decline had lower eGFR and higher urine protein-to-creatinine ratio at baseline than participants with the other eGFR trajectory patterns. The APOL1 high-risk group was associated with a greater odds for the steady decline pattern than the APOL1 low-risk group (unadjusted odds ratio, 2.45; 95% confidence interval, 1.62 to 3.69). This association remained significant after adjusting for demographic factors, baseline eGFR, urine protein-to-creatinine ratio, treatment assignment, and follow-up time (adjusted odds ratio, 1.59; 95% confidence interval, 1.00 to 2.52).
Conclusions: Among patients with CKD attributed to hypertension, those with the APOL1 high-risk genotype were more likely to experience a steady decline trajectory in eGFR than those without the APOL1 high-risk genotype. These findings suggest a persistent underlying pathophysiologic process in those patients with the APOL1 high-risk genotype.
(Copyright © 2016 by the American Society of Nephrology.)