Evaluation of a new tool for morbidity assessment in congenital cardiac surgery

To date, no instrument to assess morbidity in congenital cardiac surgery has been validated. In the Aristotle system, morbidity is accounted for by a subjective assessment of length of intensive care unit stay. A previously published Morbidity Index (MI), still in development, has been derived from objective data. The present study aims to assess the feasibility and utility of the MI at a single institution and its association with the Aristotle Comprehensive Complexity (ACC) score.

Patients undergoing congenital cardiac surgery at our institution were enrolled retrospectively. The MI was calculated from the nonweighted sum of its components. The ability of the ACC to predict the components was estimated.

The MI increased more than length of stay across procedures with increasing complexity. Renal failure requiring long-term dialysis was not observed. A requirement for temporary dialysis, which is not an MI component, correlated well with the MI (r = 0.51, p < 0.001). The ACC was a good predictor for most components of the MI: length of intensive care unit stay 3 days or more, time to extubation, postoperative extracorporeal assistance, and, for temporary dialysis, with areas under the receiver operating characteristics curve of 0.67 (0.65, 0.70), 0.71 (0.68, 0.74) , 0.84 (0.75, 0.91), and 0.83 (0.77, 0.87) respectively.

Implementation of the MI in the Aristotle system will improve prediction of complications and long lengths of stay, making it a better morbidity indicator than length of intensive care unit stay. Requirement for temporary dialysis may be considered as an MI component.