Abstract
Objective: To assess the efficacy of staging criteria (Renal Angina Index-RAI & Acute Kidney Injury Network-AKIN), and biomarker Cystatin-C in predicting acute kidney injury (AKI) following congenital cardiac surgery.
Methods: Study included 52 consecutive patients undergoing congenital heart surgery at our hospital between March-May 2023. AKIN criteria, RAI score and serum Cystatin-C level were assessed within 24-48 hours of surgery. Chi-square/ Fisher's exact test, and Student’s ‘t’ test analysed variable association. Receiver operating characteristic (ROC) curve determined the predictive value for RAI and Cystatin-C.
Results: The mean age was 2.42 ± 2.6 years, 24 (46%) were male. RAI was positive (score ≥ 8) in 25 (48.08%) patients postoperatively. 92% with AKI by RAI had Stage 1 AKIN and 8% had Stage 2 & 3 AKIN. AKI by RAI and AKIN staging correlated with each other (p = 0.227). Preoperative creatinine level predicted AKI by RAI (p= 0.024).
Serum Cystatin-C levels were significantly associated with AKI (n=4) (p=0.001). The Area under the curve for RAI for predicting AKI was 0.81 (0.57 –1) (p= 0.046) and the cut-off value for predicting AKI was > 9, with a diagnostic accuracy of 87.8%. The Area under the curve for Cystatin-C for predicting AKI was 0.93 (0.85 –1) (p=0.004) and the cut-off value for predicting AKI was > 1.3 mg/dl, with a diagnostic accuracy of 95.1%.
Conclusions: Preoperative creatinine and postoperative Cystatin-C predict postoperative AKI. RAI and AKIN criteria are comparable in predicting AKI. Cystatin-C has a higher diagnostic accuracy for AKI than RAI.