A prognostic model for predicting waiting-list mortality for a total national cohort of adult heart-transplant candidates

BACKGROUND: Current trends in medical management of advanced heart failure and transplant medicine and the enactment of a national transplant law forced a change toward allocation driven by disease severity. OBJECTIVE: The aim of this study was to create a model for predicting waiting-list survival on the basis of simple clinical parameters. METHODS: The clinical profiles of all patients registered for heart transplantation in Germany in 1997 (n=889) were used as a derivation set, and the total German 1998 cohort (n=897) was used as a validation set. The model was validated by the c statistic and by comparison of risk stratified mortality rates. The validated model was fine tuned by the appropriate calibration procedures. The data were first classified into physiologic subscores: an urgency score, a left ventricular heart failure score, a right ventricular heart failure score, and a systemic heart failure score. A stepwise modeling procedure was undertaken using these subscores as factors as well as the recipient's age, ABO blood group, and body surface area. RESULTS: The urgency and the left ventricular subscore were found to be significantly associated with waiting-list mortality. A summary index termed German Transplant Society (GTS) score was then calculated on the basis of seven parameters contained in these two subscores. The GTS score was able to predict waiting-list mortality risks for the 1998 cohort: 1-year mortality before transplantation was 71%, 34%, 11% for the high, medium, and low risk groups, respectively. CONCLUSION: The use of this continuous disease severity index may improve the selection of cardiac transplant candidates.