Albuminuria and estimated glomerular filtration rate independently associate with acute kidney injury

Abstract

Acute kidney injury (AKI) is increasingly common and a significant contributor to excess death in hospitalized patients. CKD is an established risk factor for AKI; however, the independent graded association of urine albumin excretion with AKI is unknown. We analyzed a prospective cohort of 11,200 participants in the Atherosclerosis Risk in Communities (ARIC) study for the association between baseline urine albumin-to-creatinine ratio and estimated GFR (eGFR) with hospitalizations or death with AKI. The incidence of AKI events was 4.0 per 1000 person-years of follow-up. Using participants with urine albumin-to-creatinine ratios <10 mg/g as a reference, the relative hazards of AKI, adjusted for age, gender, race, cardiovascular risk factors, and categories of eGFR were 1.9 (95% CI, 1.4 to 2.6), 2.2 (95% CI, 1.6 to 3.0), and 4.8 (95% CI, 3.2 to 7.2) for urine albumin-to-creatinine ratio groups of 11 to 29 mg/g, 30 to 299 mg/g, and ≥300 mg/g, respectively. Similarly, the overall adjusted relative hazard of AKI increased with decreasing eGFR. Patterns persisted within subgroups of age, race, and gender. In summary, albuminuria and eGFR have strong, independent associations with incident AKI.

Figure 1.

AKI incidence per 1000 person-years (with 95% CI) increases with increasing UACR (<10, 10 to 29, 30 to 299, and ≥300 mg/g) by subgroups of gender, race, age, and presence of CKD.

Figure 2.

Relative hazard of AKI increases with increasing continuous UACR, adjusted for eGFR, age, gender, race, and cardiovascular risk factors. Linear spline model with a reference UACR of 5 mg/g and knots at 10, 30, and 300 mg/g UACR. The shaded area represents 95% CI. Cardiovascular risk factors include total cholesterol, presence of diabetes, prevalent cardiovascular disease, smoking status, and measured systolic BP.

Figure 3.

Relative hazard of AKI decreases with increasing continuous eGFR adjusted for UACR, age, gender, race, and cardiovascular risk factors. Linear spline model with a reference eGFR of 95 ml/min per 1.73 m² and knots at 45, 60, 75, 90, and 105 ml/min per 1.73 m². The shaded area represents 95% CI. Cardiovascular risk factors include total cholesterol, presence of diabetes, prevalent cardiovascular disease, smoking status, and measured systolic BP.