Modified Renal Angina Index for Prediction of Severe Acute Kidney Injury

Prediction of severe AKI is important for timely action.Novel biomarkers have been proposed for the early detection of AKI, but a lack of data on sensitivity and specificity, availability, and high cost also makes it difficult. 1,2There are only a few studies on the early prediction of severe AKI [Stage 2 and 3 AKI network (AKIN)] based on risk factor stratification in the ICU. 3 The Renal Angina Index (RAI), determined based on changes in renal function, was proposed to risk-stratify critically ill children at high risk of AKI.The concept of renal angina was introduced to highlight the characteristics of renal injury as an analogy to the concept of angina pectoris. 4The RAI is assumed to serve as a marker for detecting early signs of persistent AKI.The RAI in adults involved a consistent, albeit more complicated, definition compared with that used in pediatric ICU patients [Supplementary Material].We used AKIN criteria for calculation of AKI (definition of increase in serum creatinine>0.3mg/dL or urine output<0.5mL/kg/h for>6 hours).The proposed definition for adult RAI included serum creatinine and urine output.RAI in our study was used with a minor modification, i.e., the addition of diabetes mellitus as a co-morbid condition.This was adapted from an Asian study cohort in countries from Japan and Thailand. 5The score was defined as the worst condition score multiplied by the creatinine score and consisted of 1,2,3,4, 6, 8, 10, 12, 24, and 408 [Figure 1].We used RAI>8 as a cut-off for the prediction of severe AKI, based on a study by Basu et al. 4 The study comprised 372 adults (age>18) of either sex, admitted to the ICU with stage 1 AKIN.[Supplementary Table 1] Those with stage 3 AKIN at presentation, acute on CKD, previous renal transplantation, and pediatric patients were excluded.RAI was assessed; details of kidney replacement therapy (KRT) and mortality were also reported.