Comparison of Cleveland Clinic Score, Simplified Renal Index (SRI), and Mehta Tool in Predicting Renal Replacement Therapy after Cardiac Surgery
Background: An important risk factor for adverse outcome after cardiac surgery is the development of cardiac surgery related acute kidney injury (CS-AKI), as evidenced by a reduction in glomerular filtration rate (GFR). Several scoring models have been developed in order to facilitate risk stratification and improve clinical decision-making, however, these models lack sufficient external validation especially in the local setting. This study aims compare the three available scoring systems (Cleveland Score, Simplified Renal Index and Mehta Tool) in predicting renal replacement therapy after cardiac surgery in a local tertiary hospital.
Methods: This is a retrospective cohort study among patients who underwent cardiac surgery at St. Luke’s Medical Center – Quezon City from January 2009 to December 2013. Patients with recorded variables useful in all scoring sytems were included. Categorical variables were compared between groups with and without renal replacement therapy (RRT) or severe acute kidney injury (AKI) using x2 test, and continuous variables were compared using 2-sample t test or Wilcoxon rank-sum test. Logistic regression models were used to calculate the area under the receiver-operating curve (AUROC) for the prediction of RRT or severe AKI using each scoring system.
Results: A total of 153 patients were included for analysis. All three scoring systems showed significantly higher score for the RRT group versus the non-RRT group as seen with high Chi-squared values and low p-values < 0.050. Logistic regression showed Mehta tool to be the most predictive of RRT with R2 of 0.58, followed by the Cleveland Clinic Score (R2 = 0.42) and SRI (R2 = 0.29).
Conclusion: Any of the three scoring systems is sufficient to predict acute kidney injury requiring renal replacement therapy in patients undergoing cardiac surgery in the local setting. However, the Mehta Tool had the best predictive capability among the three scoring systems.