Mortality prediction after kidney transplantation: comparative clinical use of 7 comorbidity indices

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.

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.

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.

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.