Abstract 18410: Predicting Long-Term Mortality Following Coronary Artery Bypass Graft Surgery

Abstract

Background: Simplified bedside risk scores have been created to predict short-term mortality, e.g. in-hospital mortality, following coronary artery bypass graft (CABG) surgery. However, no such scores have been developed to predict long-term mortality. Objectives: To create a simplified risk score to predict long-term mortality following CABG surgery. Methods: The New York State's Cardiac Surgery Reporting System was used to identify the study population, which consisted of 8,413 patients who underwent isolated CABG surgery and were discharged in July through December 2000. The National Death Index was used to ascertain patients' vital status through the end of 2007. A Cox proportional hazards model was fit to predict death following CABG surgery using pre-procedural risk factors. Then points were assigned to significant predictors of death based on the values of their regression coefficients, and for each possible point total (sum of points of risk factors) the predicted risks of death at years 1, 3, 5, and 7 were calculated. Results: Kaplan-Meier analysis showed that the 7-year mortality rate was 22.6% in the study population. Significant predictors of death included age, body mass index, ejection fraction, left main coronary artery disease, cerebrovascular disease, peripheral arterial disease, congestive heart failure, chronic obstructive pulmonary disease, diabetes, and renal failure. The C statistics measuring the discrimination of the Cox proportional hazards model were 0.781, 0.773, 0.770, and 0.780 for mortality at 1, 3, 5, and 7 years of follow-up. The points assigned to these risk factors ranged from 1 to 7; and the possible point totals ranged from 0 to 24. The observed and predicted risks of death at years 1, 3, 5, and 7 across patient groups stratified by point totals were highly correlated. Conclusion: We developed a simplified risk score for predicting the risk of mortality following CABG surgery at 1, 3, 5, and 7 years. This long-term risk score can be used by providers and patients as an aid in determining the appropriate treatment for patients with coronary artery disease based on each patient's specific risk factors.