The assessment of complexity in congenital cardiac surgery based on objective data.

When designed in 2000, the Aristotle Complexity Score was entirely based on subjective probability. This approach, based on the opinion of experts, was considered a good solution due to the limited amount of data available. In 2008, the next generation of the complexity score will be based on observed data available from over 100,000 congenital cardiac operations currently gathered in the congenital cardiac surgery databases of the Society of Thoracic Surgeons and the European Association for Cardio-Thoracic Surgery. A mortality score is created based on 70,000 surgeries harvested in the congenital databases of The Society of Thoracic Surgeons and The European Association for Cardio-Thoracic Surgery. It is derived from 118 congenital cardiovascular operations, representing 91% of the operations and including 97% of the patients. This Mortality Index of the new Aristotle Complexity Score could further be stratified into 5 levels with minimal within-group variation and maximal between-group variation, and may contribute to the planned unification of the Aristotle Complexity Score with the Risk Adjustment for Congenital Heart Surgery system. Similarly, a score quantifying morbidity risk is created. Due to the progress of congenital cardiac surgery, the mortality is today reduced to an average of 4%. No instrument currently exists to measure the quality of care delivered to the survivors representing 96% of the patients. An objective assessment of morbidity was needed. The Morbidity Index, based on 50,000 operations gathered in the congenital databases of The Society of Thoracic Surgeons and The European Association for Cardio-Thoracic Surgery, is derived from 117 congenital cardiovascular operations representing 90% of the operations and including 95% of the patients. This morbidity indicator is calculated on an algorithm based on length of stay in the hospital and time on the ventilator. The mortality and morbidity indicators will be part of the next generation of the complexity score, which will be named the Aristotle Average Complexity Score. It will be based on the sum of mortality, morbidity, and subjective technical difficulty. The introduction of objective data in assessment of mortality and morbidity in congenital cardiac surgery is a significant step forward, which should allow a better evaluation of the complexity of the operations performed by a given centre or surgeon.