Point-of-Care Urinary Biomarker Testing for Risk Prediction in Critically Injured Combat Casualties

Abstract

Risk prediction is important during combat operations because resources are limited and triage decisions must be rapid and accurate. We evaluated 2 point-of-care urinary biomarker tests for risk prediction in combat casualties. This was an observational cohort study of critically injured military personnel admitted to Craig Joint Theater Hospital in Afghanistan from October 2012 to December 2013. We collected urine within 3 hours of admission and measured urinary biomarkers with NephroCheck and a neutrophil gelatinase-associated lipocalin dipstick (NGALds) to evaluate their ability to predict a combined end point of need for renal replacement therapy or death. Odds ratios (ORs) were calculated and receiver operator characteristic curves were generated for both tests. A total of 89 patients were included for analysis. The median Injury Severity Score was 18 and the combined end point occurred in 12 (13.5%) patients. NephroCheck was not associated with the combined end point (OR 1.56; 95% CI 0.81 to 3.03; p= 0.19) and the area under the curve of the receiver operator characteristic curve was 0.65. The NGALds was highly associated with the combined end point (OR 4.93; 95% CI 2.18 to 11.14; p < 0.001) and the area under the curve of the receiver operator characteristic curve was 0.84. The NGALds remained significantly associated with the combined end point in a logistic regression model that included Injury Severity Score as a covariate (OR 4.10; 95% CI 1.74 to 9.67; p=0.001). Measurement of urinary biomarkers with an NGALds, but not NephroCheck, predicts poor outcomes in combat casualties. An NGALds is a simple urine dipstick that could be deployed to combat zones to prioritize aeromedical evacuation, help with triage decisions, and predict resource use.