Urinary biomarkers predict progression and adverse outcomes of acute kidney injury in critical illness.

Background: Acute kidney injury (AKI) is common in hospitalized patients and is associated with high morbidity and mortality. The Dublin Acute Biomarker Group Evaluation study is a prospective cohort study of critically ill patients (n = 717). We hypothesized that novel urinary biomarkers would predict progression of AKI and associated outcomes.

Methods: The primary (diagnostic) analysis assessed the ability of biomarkers levels at the time of early Stage 1 or 2 AKI to predict progression to higher AKI stage, renal replacement therapy (RRT) or death within 7 days of intensive care unit admission. In the secondary (prognostic) analysis, we investigated the association between biomarker levels and RRT or death within 30 days.

Results: In total, 186 patients had an AKI within 7 days of admission. In the primary (diagnostic) analysis, 8 of the 14 biomarkers were independently associated with progression. The best predictors were cystatin C [adjusted odds ratio (aOR) 5.2; 95% confidence interval (CI) 1.3-23.6], interleukin-18 (IL-18; aOR 5.1; 95% CI 1.8-15.7), albumin (aOR 4.9; 95% CI 1.5-18.3) and neutrophil gelatinase-associated lipocalin (NGAL; aOR 4.6; 95% CI 1.4-17.9). Receiver-operating characteristics and net reclassification index analyses similarly demonstrated improved prediction by these biomarkers. In the secondary (prognostic) analysis of Stages 1-3 AKI cases, IL-18, NGAL, albumin and monocyte chemotactic protein-1 were also independently associated with RRT or death within 30 days.

Conclusions: Among 14 novel urinary biomarkers assessed, cystatin C, IL-18, albumin and NGAL were the best predictors of Stages 1-2 AKI progression. These biomarkers, after further validation, may have utility to inform diagnostic and prognostic assessment and guide management of AKI in critically ill patients.