Urinary NGAL-Positive Acute Kidney Injury and Poor Long-term Outcomes in Hospitalized Patients

• Main Authors: Eugenia Singer, Eva V. Schrezenmeier, Antje Elger, Evelyn R. Seelow, Alexander Krannich, Friedrich C. Luft, Kai M. Schmidt-Ott
• Format: Article
• Language: English
• Published: Elsevier 2016-09-01
• Series: Kidney International Reports
• Subjects: acute kidney injury; long-term outcomes; neutrophil gelatinase–associated lipocalin (NGAL)
• Online Access: http://www.sciencedirect.com/science/article/pii/S2468024916300420

Neutrophil gelatinase−associated lipocalin (NGAL) is a widely studied biomarker of renal tubular injury. Urinary NGAL (uNGAL) during acute kidney injury (AKI) predicts short-term adverse outcomes. However, the long-term predictive value is unknown. Methods: We performed a prospective observational study of 145 patients with hospital-acquired AKI according to Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease (RIFLE) criteria and analyzed the long-term predictive value of uNGAL at the time of AKI. We defined a composite outcome of all-cause mortality and the development of end-stage renal disease (ESRD). Results: In all, 61 AKI patients died and 22 developed ESRD within 6 months. The uNGAL levels were significantly higher in patients with poor long-term outcomes. uNGAL levels ≥362 μg/l (highest quartile) and uNGAL levels between 95 and 362 μg/l (third quartile) were associated with hazard ratios of 3.7 (95% confidence interval, 2.1–6.5) and 1.9 (1.1–3.5), respectively, compared with uNGAL levels <95 μg/l (lower quartiles). After 6 months, 67% and 43% of patients within the highest and third uNGAL quartile, respectively, had either progressed to ESRD or died, compared to only 21% of patients with uNGAL in the lower 2 quartiles (P < 0.001). In multivariable Cox regression analyses accounting for conventional predictors, uNGAL was the strongest independent predictor of adverse long-term outcomes. The association of uNGAL levels and poor long-term outcomes remained significant in the subgroup of 107 AKI survivors discharged without requiring dialysis (P = 0.002). Discussion: These data indicate that elevated uNGAL levels at AKI diagnosis predict poor long-term outcomes.