Additive value of blood neutrophil gelatinase-associated lipocalin to clinical judgement in acute kidney injury diagnosis and mortality prediction in patients hospitalized from the emergency department

Abstract

Introduction: Acute kidney injury (AKI) is a common complication among hospitalized patients. The aim of this study was to evaluate the utility of blood neutrophil gelatinase-associated lipocalin (NGAL) assessment as an aid in the early risk evaluation for AKI development in admitted patients.

Methods: This is a multicenter Italian prospective emergency department (ED) cohort study in which we enrolled 665 patients admitted to hospital from the ED.

Results: Blood NGAL and serum creatinine (sCr) were determined at ED presentation (T0), and at: 6 (T6), 12 (T12), 24 (T24) and 72 (T72) hours after hospitalization. A preliminary assessment of AKI by the treating ED physician occurred in 218 out of 665 patients (33%), while RIFLE AKI by expert nephrologists was confirmed in 49 out of 665 patients (7%). The ED physician's initial judgement lacked sensitivity and specificity, overpredicting the diagnosis of AKI in 27% of the cohort, while missing 20% of those with AKI as a final diagnosis.

Conclusions: Our study demonstrated that assessment of a patient's initial blood NGAL when admitted to hospital from the ED improved the initial clinical diagnosis of AKI and predicted in-hospital mortality. Blood NGAL assessment coupled with the ED physician's clinical judgment may prove useful in deciding the appropriate strategies for patients at risk for the development of AKI.See related commentary by Legrand et al., http://ccforum.com/content/17/2/132.

Figure 1

Flow diagram of the study, patients' distribution and outcome.

Figure 2

Mean ± SD neutrophil gelatinase-associated lipocalin (NGAL) and serum creatinine (sCr) values at each considered time of serial assessment.

Figure 3

Mean ± SD neutrophil gelatinase-associated lipocalin (NGAL) (A) and serum creatinine (sCr) (B) at T0 by final diagnosis.

Figure 4

T0 receiver-operating characteristic (ROC) curves by adjudicated acute kidney injury (AKI) based on neutrophil gelatinase-associated lipocalin (NGAL), clinical judgment of developing AKI, and NGAL combined with clinical judgment.

Figure 5

Neutrophil gelatinase-associated lipocalin (NGAL) (T0) predictive value of in-hospital mortality. Odds ratio (OR), negative predictive value (NPV), positive predictive value (PPV) on the basis of NGAL T0 threshold 400 ng/ml. N = no exitus, Y = yes, exitus.

Figure 6

Risk stratification comparing groups of patients obtained by combining T0 serum creatinine (sCr) +/- and neutrophil gelatinase-associated lipocalin (NGAL) +/-. Rates of clinical events for the combined endpoint of renal replacement therapy (RRT) or in-hospital mortality.