Changes in GFR and Albuminuria in Routine Clinical Practice and the Risk of Kidney Disease Progression

Abstract

Changes in urinary albumin-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR) have been used separately as alternative kidney disease outcomes in randomized trials. We tested the hypothesis that combined changes in UACR and eGFR predict advanced kidney disease better than either alone. Observational cohort study. 91,319 primary care patients assembled from the Clinical Practice Research Datalink in the United Kingdom between 2000 and2015. Changes in UACR and eGFR (categorized as≥30% increase, stable, or≥30% decrease), alone and in combination, over a 3-year period. The primary outcome was advanced CKD (sustained eGFR<30 mL/min/1.73 m2); secondary outcomes included kidney failure, cardiovascular disease, and all-cause mortality. Multivariable Cox regression with bias from missing values assessed using multiple imputation; discrimination statistics compared across exposure groups. 91,319 individuals were studied, with amean eGFR of 72.6 mL/min/1.73 m2 and medianUACR of 9.7 mg/g; 70,957 (77.7%) had diabetes. During a median follow-up of 2.9 years, 2,541 people progressed to advanced CKD. Compared with stable values, hazard ratios for a≥30% increase in UACR and≥30% decrease in eGFR were 1.78 (95% CI, 1.59-1.98) and 7.53 (95% CI, 6.70-8.45), respectively, for the outcome of advanced CKD. Compared with stable values of both, the hazard ratio for the combination of an increase in UACR and a decrease in eGFR was 15.15 (95% CI, 12.43-18.46) for the outcome of advanced CKD. The combination of changes in UACR and eGFR predicted kidney outcomes better than either alone. Selection bias, relatively small proportion of individuals without diabetes, and very few kidney failure events. In a large-scale general population, the combination of an increase in UACR and a decrease in eGFR was strongly associated with the risk of advanced CKD. Further assessment of combined changes in UACR and eGFR as an alternative outcome for kidney failure in trials of CKD progression is warranted.