Evaluation of the Utility of the Renal Angina Index for the Early Diagnosis of Severe Acute Kidney Injury in Critically Ill Pediatric Patients in Three Institutions in Low-Resource Country

Abstract Background: Acute kidney injury (AKI) occurring in up to 30% of children admitted to the intensive care unit. Creatinine is the primary functional marker for AKI; however, its utility in early diagnosis is limited. The renal angina index (RAI) has proven to be an effective predictive model for early injury, with limited evidence in Colombia regarding its performance. Methods: Prospective, analytical, multicenter diagnostic test study in critically ill children in three pediatric intensive care units (PICUs) in Medellín, Colombia. We assess the diagnostic utility of the positive RAI as an early predictor of severe AKI. Results: Between August 2022 and February 2023, 191 patients were analyzed. The incidence of AKI was 12.5/100 patients, 26% exhibited a positive RAI, 12.6% developed severe AKI at 72 hours. Among RAI-positive patients when comparing with negative, 75% experienced severe AKI (RR 3.23; 95% CI 1.61-6.49), 14% required renal support therapy (RR 2.09; 95% CI 0.95-4.59), and 8% died within 28 days (p=0.964). The sensitivity of RAI for early diagnosis of severe AKI was 85.71%, specificity 78.3%, PPV 24%, NPV 98.5%, AUC 0.812 (95% CI 0.72-0.92). To the patients with a doubled baseline creatinine, 33% developed AKI at 72 hours (RR 1.45; 95% CI 1.09-1.92). Conclusions: The RAI proved to be a marker for early prediction of severe AKI in critically ill children, potentially serving as a useful tool to improve outcomes related to the presence of AKI compared to the isolated use of creatinine.