Pos-067 Utility Of Neutrophil Gelatinase-Associated Lipocalin (Ngal) In Diagnosis Of Acute Kidney Injury Among Children With Sickle Cell Anemia Hospitalised With Vaso-Occlusion

Abstract

Introduction: Diagnosis of acute kidney injury (AKI) in low-income settings is challenging as creatinine testing is not routinely available and serum creatinine is affected by age, nutritional status and glomerular hyperfiltration, a feature of sickle cell anemia (SCA). Alternative point-of-care biomarkers are needed to facilitate early detection of AKI in at-risk populations. We evaluated the diagnostic accuracy of a semi-quantitative point-of-care test of urine neutrophil gelatinase-associated lipocalin (uNGAL) to diagnose AKI in SCA at hospital admission. Methods: We enrolled 185 Ugandan children with SCA 2 to 18 years of age admitted with vaso-occlusive crises (VOC) and age-matched controls in steady state. AKI was defined using the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines based on a ≥1.5-fold change in creatinine within seven days or an absolute change of ≥0.3mg/dl within 48 hours excluding children with 1.5-fold change in creatinine from 0.2mg/dL to 0.3mg/dL. Creatinine was measured using the handheld iSTAT blood analyzer and CHEM8+ cartridges based on an enzymatic assay with amperometric detection. Urine NGAL was measured using a semi-quantitative point-of-care lateral flow uNGAL test on fresh urine (uNGALPOC) or quantitatively assessed by ELISA (uNGALELISA) on cryopreserved urine at the end of the study. The diagnostic accuracy of uNGAL was evaluated by comparing the area under receiver operating characteristic (AUROC) curves. Results: A total of 50 children (27.0%) had AKI over hospitalization. Urine NGAL levels were significantly higher in children with AKI compared to children without AKI irrespective of test methodology (uNGALELISA p<0.001, uNGALPOC p<0.001) and there was a significant increase in uNGAL levels across stages of AKI (p<0.0001 for both uNGALELISA and uNGALPOC). Levels of uNGALELISA and uNGALPOC were strongly correlated with a Spearman's rho of 0.805. When evaluating the diagnostic accuracy to identify AKI over hospitalization, the semi-quantitative lateral flow test of uNGALPOC had an equivalent AUROC to uNGALELISA with AUROCs of 0.71 for both tests. The uNGALPOC had the best performance in diagnosing AKI in children <5 years of age with an AUC of 0.95 (95% CI 0.85, 1.00) as well as children with evidence of an acute inflammatory event (hyperleukocytosis, AUC 0.76, 95% CI 0.65, 0.87) and hemoglobinuria on admission with an AUC of 0.79 (95% CI 0.68, 0.90). Conclusions: These results demonstrate that a point-of-care semi-quantitative uNGAL test had comparable ability to identify AKI compared to quantitative ELISA. Additional studies are needed to evaluate the utility of the point-of-care test across different patient populations.