Common Kidney Function Tests Predict AKI Risk

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Widely assessed kidney function measures are consistently and strongly related to the risk of acute kidney injury (AKI), independently of other risk factors, according to a pair of meta-analyses in the American Journal of Kidney Diseases.

One analysis included eight general population cohorts and five chronic kidney disease (CKD) cohorts participating in the CKD Prognosis Consortium. Potential predictors of AKI hospitalization were evaluated, including diabetes and hypertension, estimated GFR (eGFR, calculated by the 2009 CKD Epidemiology Collaboration creatinine equation), and urine albumin-to-creatinine ratio (ACR).

With and without diabetes or hypertension, low eGFR and high ACR were associated with higher AKI risk. Diabetic patients were generally at higher AKI risk than were nondiabetic patients at any level of eGFR, although the difference was less pronounced in the lower range of eGFR. A similar pattern was noted for ACR. Hypertensive patients were at higher risk than were patients without hypertension, although the risks were comparable at eGFR levels less than 60 mL/min/1.73 m2 and ACR values greater than 30 mg/g.

The second meta-analysis evaluated the AKI risk associated with eGFR and ACR in terms of age, race, and sex. Acute kidney injury occurred in 1.3 percent of the general population cohort members (mean follow-up time, 4 years) versus 2.6 percent of CKD cohort members (mean follow-up time, 1 year). Again, both test results were strongly associated with AKI. Older age and male sex were significant risk factors for AKI, although the associations were weaker in the presence of CKD. For African Americans, AKI risk was elevated at higher eGFR levels and at most ACR levels.

The results suggest that common laboratory measures of pre-existing kidney health could be the strongest predictors of AKI risk—even more so than diabetes, hypertension, age, race, and sex. The researchers conclude, “These results suggest the primacy of low eGFR and high ACR in AKI risk stratification—an observation that could guide preventative efforts” [James MT, et al. A meta-analysis of the association of estimated GFR, albuminuria, diabetes mellitus, and hypertension with acute kidney injury. Am J Kidney Dis 2015; doi:10.1053/j.ajkd.2015.02.338; and Grams ME, et al. A meta-analysis of the association of estimated GFR, albuminuria, age, race, and sex with acute kidney injury. Am J Kidney Dis 2015; doi:10.1053/j.ajkd.2015.02.337].