Mortality Prediction After Kidney Transplantation: Comparative Clinical Use of 7 Comorbidity Indices

Abstract

Objectives: Despite comorbidity associated with chronic kidney disease, little data exist applying comorbidity scoring systems to renal transplant recipients. This study compared the performance of 7 established comorbidity scores in predicting mortality after kidney transplantation.

Materials and Methods: We retrospectively analyzed prospectively collected data from 2033 incident renal transplant recipients. Comorbidity was assessed at baseline, and the following scores were derived: Recipient Risk Score, Charlson Comorbidity Index, Age-adjusted Charlson Comorbidity Index, Modified End-Stage Renal Disease Charlson Comorbidity Index, Foley Score, Wright-Khan Index, and Davies Index. Cox models investigated the association of each comorbidity score with mortality; performance characteristics were tested using receiver operating characteristic curve analysis.

Results: Age-stratified Cox analyses showed the Recipient Risk Score-based model displayed the best fit, and receiver operating characteristic curve analysis showed the Recipient Risk Score demonstrated greatest predictive use (5-year mortality c-statistic: 0.787). The independent effect of age on mortality was demonstrated after analysis of scores not containing age as a component (the Charlson Comorbidity Index, the Modified End-Stage Renal Disease Charlson Comorbidity Index, the Davies Index); addition of age to these scores improved fit.

Conclusions: Of the currently available comorbidity scores, the Recipient Risk Score demonstrated greatest use. This has implications for deceased-donor allocation algorithms, assessment of confounders in clinical research, and potentially, individual patient management.