Prediction of cardiac surgery associated acute kidney injury using response to loop diuretic and urine neutrophil gelatinase associated lipocalin

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BackgroundCardiac surgery associated acute kidney injury (CS-AKI) is common. Urine response to loop diuretic and urine neutrophil gelatinase associated lipocalin (uNGAL) are separately associated with CS-AKI. We aimed to determine whether urine response to loop diuretic and uNGAL together were associated with postoperative day 2–4 CS-AKI.MethodsTwo-center prospective observational study (ages 0–18 years). uNGAL (8–12 h after admission) (ng/mL) and urine response to loop diuretic (6 h for bolus furosemide and 12 h for infusion bumetanide) (mL/kg/hr) were measured. All diuretic doses were converted to furosemide equivalents. The primary outcome was day 2–4 CS-AKI. Patients were sub-phenotyped using a priori cutoffs (uNGAL + ≥ 100 ng/mL and UOP + < 1.5 mL/kg/hr) and optimal cutoffs (uNGAL + ≥ 127 ng/mL and UOP + ≤ 0.79 mL/kg/hr): 1) uNGAL–/UOP–, 2) uNGAL–/UOP + , 3) uNGAL + /UOP–, and 4) uNGAL + /UOP + . Multivariable regression was used to assess the association of uNGAL, UOP and each sub-phenotype with outcomes.Results476 patients were included. CS-AKI occurred in 52 (10.9%). uNGAL was associated with 2.59-fold greater odds (95%CI: 1.52–4.41) of CS-AKI. UOP was not associated with CS-AKI. Compared with uNGAL + alone, uNGAL + /UOP + improved prediction of CS-AKI using a priori and optimal cutoffs respectively (AUC 0.70 vs. 0.75). Both uNGAL + /UOP + (IQR OR:4.63, 95%CI: 1.74–12.32) and uNGAL + /UOP– (IQR OR:5.94, 95%CI: 2.09–16.84) were associated with CS-AKI when compared with uNGAL–/UOP–.ConclusionsuNGAL is associated with CS-AKI. The sub-phenotype association was largely driven by uNGAL. Future studies standardizing diuretic dose and timing may be needed to refine the combined performance for clinical decision making.Graphical abstractA higher resolution version of the Graphical abstract is available as Supplementary information