Performance of Cleveland, Mehta, and Simplified Renal Index scores for predicting dialysis-requiring acute kidney injury after aortic <i>vs.</i> non-aortic cardiac surgery (2006–2023, 6160 patients)

Acute kidney injury requiring renal replacement therapy (RRT-AKI) is a serious complication after cardiac surgery, especially in aortic procedures. Validated risk models, such as the Cleveland Clinic Score, Mehta tool, and Simplified Renal Index (SRI) are widely applied, but their performance in predicting after aortic versus non-aortic cardiac surgery remains uncertain. We conducted a retrospective cohort study of 6,160 patients undergoing cardiac surgery (1,002 aortic and 5,158 non-aortic) (2006-2023) at a teaching hospital in Hong Kong. Predictive performance of the risk scores were assessed using the area under the receiver operating characteristic curve (AUC). Differences in AUC were assessed using DeLong's test. Hosmer-Lemeshow goodness-of-fit test was used to assess calibration. In this cohort, 3.2% developed RRT-AKI. RRT-AKI was more common after aortic surgery than non-aortic surgery (6.7 <i>vs.</i> 2.5%; <i>p</i> = <.001). Thirty-day mortality reached 40% in patients with acute kidney injury requiring renal replacement therapy after cardiac surgery. In the non-aortic surgery cohort, the three scores only showed moderate discriminatory power (worse than original cohorts) and good calibration: 0.77 (95% CI, 0.72-0.81) and <i>p</i> = .62 (Cleveland); 0.75 (95% CI, 0.70-0.80) and <i>p</i> = .10 (Mehta); and 0.75 (95% CI, 0.71-0.79) and <i>p</i> = .65 (SRI). In the aortic surgery cohort, there was only moderate discriminatory power and good calibration: AUC 0.70 (95% CI, 0.63-0.77) and <i>p</i> = .57 (Cleveland); 0.67 (95% CI, 0.59-0.74) and <i>p</i> = .67 (Mehta); 0.65 (95% CI, 0.58-0.72) and <i>p</i> = .79 (SRI). Currently established risk scores only have moderate discriminatory power (range of AUC 0.65-0.77) to predict RRT-AKI after both cardiac and aortic surgery.