SP4.4 A Prospective Diagnostic study investigating Urinary Biomarkers of AKI in Major Abdominal Surgery (The AKI-BioMAS Study)

Abstract

Abstract Aims To characterize biomarker performance in predicting Acute Kidney Injury (AKI) in Major Abdominal Surgery using both the Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine (AKISCr) and urine output (AKIUO) criteria. Post-operative AKI is associated with increased morbidity and mortality. Research assessing AKI biomarkers has focussed on cardiac, vascular and transplant surgery cohorts. Few studies have addressed Major Abdominal Surgery. Methods This prospective observational diagnostic study was conducted on 488 major abdominal surgery patients. Urine was collected four hours post-surgery. Biomarkers measured were NGAL, KIM-1, DKK-3 and IGFBP-7*TIMP-2. Diagnostic performance was assessed utilizing Receiver Operating Characteristic (ROC) curve analysis. Results 242 participants developed AKIUO (49.5%) and 43 AKISCr (8.8%). The area under the receiver operating characteristic curve (AUC) values for stage 1 AKISCr using NGAL was 0.741 (95%CI 0.699-0.770, p<0.001) and 0.871 (95%CI 0.838-.899, p<0.001) for stage 2. AUC values for IGFBP-7*TIMP-2 for stage 1 were 0.655 (95% CI 0.611-0.697, p0.003) and stage 2 0.803 (95%CI 0.764-0.837 p0.002). The AUC for KIM-1 was statistically significant for stage 1 (0.68, 95%CI 0.637-0.722) but not for stage 2. No AUC values for DKK-3 were statistically significant. Biomarkers performed poorly for stage 1 and 2 AKIUO with AUC values of <0.65. Conclusions AKI rates following Major Abdominal Surgery are dependent on criteria used. Given the numerous confounders affecting urine output post-operatively it may be that current AKIUO criteria in patients undergoing Major Abdominal Surgery may be inappropriate. This is reflected in poor diagnostic performance of biomarkers in this context. Biomarkers performed better when assessing AKISCr, with NGAL returning the highest AUC values.