Plasma Neutrophil Gelatinase-Associated Lipocalin to Predict Acute Kidney Injury After Lung Transplantation: A Multicenter Cohort Study

Abstract

<h3>Purpose</h3> Post-operative acute kidney injury (AKI) occurs in up to 65% of lung transplant recipients and is associated with chronic kidney disease and mortality. Plasma neutrophil gelatinase-associated lipocalin (pNGAL) is a biomarker of early structural kidney damage that has improved prediction of AKI compared with clinical variables alone in non-transplant patient populations. We sought to determine the association of pNGAL with AKI after lung transplantation and whether it could improve AKI prediction. <h3>Methods</h3> We included 189 lung transplant recipients enrolled in the prospective 5-center Lung Transplant Outcomes Group Acute Kidney Injury (LTOG-AKI) cohort study from 7/2017 - 6/2019. We tested pNGAL levels pre-transplant and at 6 and 24 hours post-reperfusion. We defined AKI using Kidney Disease Improving Global Outcomes creatinine criteria during the first 7 post-op days. We tested associations of pNGAL and clinical variables with AKI using the Wilcoxon rank-sum test. We constructed logistic regression models to predict AKI using pNGAL alone, clinical variables alone, and pNGAL plus clinical variables. <h3>Results</h3> AKI developed in 95 (50%) patients (45 (24%) stage 1, 21 (11%) stage 2, 29 (15%) stage 3), occurring a median of 2 (IQR 1-3) days post-op. pNGAL levels at 6h (p=0.001) and 24h (p<0.001) were significantly associated with AKI. Over 90% of 6h pNGAL levels were >150 ng/ml, the cut-off typically used to denote high risk of AKI in non-transplant populations. A model including clinical variables of recipient age and gender, transplant diagnosis and type, and lung allocation score had an area under the receiver operating characteristics (auROC) curve higher than pNGAL alone (Figure 1). Adding pNGAL to the clinical model did not improve the auROC curve. Model results were similar when defining AKI as stage 2-3 only. <h3>Conclusion</h3> Early post-lung transplant pNGAL levels were associated with AKI but did not add to clinical variables in predicting AKI.