Association Between 1-Year Changes in Urinary Albumin-to-creatinine Ratio and Kidney Disease Progression in Japanese Individuals with Diabetes: a Historical Cohort Study.

Background The National Kidney Foundation recently proposed a ≥ 30% decrease in urinary albumin–to–creatinine ratio (UACR) over 0.5–2 years as a surrogate endpoint for chronic kidney disease (CKD) progression in individuals with baseline UACR > 30 mg/g. This historical cohort study aimed to determine the applicability of a decrease in UACR, within as little as 1 year, as a surrogate endpoint for Japanese individuals with type 2 diabetes mellitus (T2D). Methods A total of 5067 individuals with T2D were divided into three groups based on 1-year change in UACR: ≥ 30% decrease (UACR decreased group), < 30% decrease and < 30% increase (UACR unchanged group), or ≥ 30% increase (UACR increased group). The primary endpoint was a composite of a ≥ 30% decline in estimated glomerular filtration rate (eGFR) or the initiation of kidney replacement therapy, whichever occurred first. Results At baseline, the proportions of individuals with normoalbuminuria, microalbuminuria, and eGFR ≥ 60 mL/min/1.73 m 2 were 68.1%, 22.1%, and 75.5%, respectively. During a median follow-up of 6.8 years, 926 individuals (18.3%) reached the composite endpoint. Adjusted hazard ratios (vs. the UACR unchanged group) for the UACR decreased and increased groups were 0.758 (95% confidence interval [CI], 0.636–0.905; P = 0.002) and 1.304 (95% CI, 1.108–1.536; P = 0.001), respectively. Conclusions These findings support the use of 1-year changes in UACR as a surrogate endpoint for the progression of CKD and the implementation of a ≥ 30% decrease in UACR as a positive efficacy endpoint in Japanese individuals with T2D and early-stage kidney disease.