Association of Albuminuria With Chronic Kidney Disease Progression in Persons With Chronic Kidney Disease and Normoalbuminuria : A Cohort Study

Abstract

Background: Albuminuria is a major risk factor for chronic kidney disease (CKD) progression, especially when categorized as moderate (30 to 300 mg/g) or severe (>300 mg/g). However, there are limited data on the prognostic value of albuminuria within the normoalbuminuric range (<30 mg/g) in persons with CKD.

Objective: To estimate the increase in the cumulative incidence of CKD progression with greater baseline levels of albuminuria among persons with CKD who had normoalbuminuria (<30 mg/g).

Design: Multicenter prospective cohort study.

Setting: 7 U.S. clinical centers.

Participants: 1629 participants meeting criteria from the CRIC (Chronic Renal Insufficiency Cohort) study with CKD (estimated glomerular filtration rate [eGFR], 20 to 70 mL/min/1.73 m²) and urine albumin-creatinine ratio (UACR) less than 30 mg/g.

Measurements: Baseline spot urine albumin divided by spot urine creatinine to calculate UACR as the exposure variable. The 10-year adjusted cumulative incidences of CKD progression (composite of 50% eGFR decline or kidney failure [dialysis or kidney transplantation]) from confounder adjusted survival curves using the G-formula.

Results: Over a median follow-up of 9.8 years, 182 of 1629 participants experienced CKD progression. The 10-year adjusted cumulative incidences of CKD progression were 8.7% (95% CI, 5.9% to 11.6%), 11.5% (CI, 8.8% to 14.3%), and 19.5% (CI, 15.4% to 23.5%) for UACR levels of 0 to less than 5 mg/g, 5 to less than 15 mg/g, and 15 mg/g or more, respectively. Comparing persons with UACR 15 mg/g or more to those with UACR 5 to less than 15 mg/g and 0 to less than 5 mg/g, the absolute risk differences were 7.9% (CI, 3.0% to 12.7%) and 10.7% (CI, 5.8% to 15.6%), respectively. The 10-year adjusted cumulative incidence increased linearly based on baseline UACR levels.

Limitation: UACR was measured once.

Conclusion: Persons with CKD and normoalbuminuria (<30 mg/g) had excess risk for CKD progression, which increased in a linear fashion with higher levels of albuminuria.

Primary funding source: None.

Figure 1.

Adjusted cumulative incidences and 5- and 10-year risk differences in adjusted cumulative incidences of CKD progression (top) and kidney failure (bottom) among UACR categories in persons with CKD and normoalbuminuria. The adjusted cumulative incidences and risk differences in adjusted cumulative incidences among comparator groups were calculated using confounder-adjusted survival curves using the G-formula method for covariate adjustment. Categories 1, 2, and 3 correspond to persons who had UACR of 0 to <5, 5 to <15 mg/g, and ≥15 mg/g, respectively. CKD = chronic kidney disease; UACR = urine albumin–creatinine ratio.

Figure 2.

The 10-year adjusted cumulative incidence for CKD progression (left) and kidney failure (right), by baseline levels of UACR. The 10-year adjusted cumulative incidence for baseline levels of UACR was calculated using confounder-adjusted survival curves using the G-formula method for covariate adjustment. CKD = chronic kidney disease; UACR = urine albumin–creatinine ratio.