OBJECTIVES: The commonly used cardiac surgery risk scores, European System for Cardiac Operative Risk Evaluation II and Society of Thoracic Surgeons score, are inaccurate in predicting mortality in the ageing patient population and do not include the biological age. This requests a need for a new risk score incorporating frailty. The aim of this study was to compare the prediction of mortality and the additive effect of comprehensive assessment of frailty score and the shortened version, frailty predicts death one year after elective cardiac surgery test on the existing risk scores.

METHODS: Six hundred four patients undergoing cardiac surgery and aged >= 65 years were included in this prospective observational study. These frailty scores are based on minor physical tests. We compared these frailty score predictions of mortality and their added value to the existing risk scores evaluated by concordance-statistics (C-statistics), integrated discrimination improvement and net reclassification improvement.

RESULTS: The median age was 73 years (21% female). C-statistics showed that comprehensive assessment of frailty score with a value of 0.69, frailty predicts death one year after elective cardiac surgery test 0.68, Society of Thoracic Surgeons score 0.70 and European System for Cardiac Operative Risk Evaluation 0.64. Frailty assessment, added to the existing risk scores, significantly improved integrated discrimination improvement up to 0.05, and net reclassification improvement up to 0.04. Frailty assessment also increased the C-statistics, but this did not reach statistical significance.

CONCLUSIONS: Frailty scores are as good as the existing risk scores for the prediction of mortality in patients undergoing cardiac surgery. Added to the existing scores, frailty assessment improves the C-statistics and integrated discrimination improvement over time.