A method to evaluate cardiac surgery mortality: phase of care mortality analysis

This is a study of a method of mortality review, adopted by the Michigan Society of Thoracic and Cardiovascular Surgeons, to enhance understanding of mortality and potentially avoidable deaths after cardiac surgery, utilizing a voluntary statewide database.

A system to categorize mortality was developed utilizing a phase of care mortality analysis approach as well as providing criteria to classify mortality as potentially "avoidable." For each mortality, the operating surgeon categorized a cardiac surgery mortality trigger into 1 of 5 time frames: preoperative, intraoperative, intensive care unit (ICU), postoperative floor, and discharge.

A total of 53,674 adult cardiac operations were performed from January 1, 2006 to June 30, 2010 with a crude mortality of 3.5% (1,905 of 53,674). Of the mortalities analyzed, 35% (618 of 1,780) were preoperative, 25% (451 of 1,780) were ICU, 19% (333 of 1,780) were intraoperative, 11% (198 of 1,780) were floor, and 10% (180 of 1,780) were discharge phase. "Avoidable" mortality triggers occurred in 53% (174 of 333) of the intraoperative, 41% (253 of 618) and (184 of 451) of the preoperative and ICU phases, 42% (83 of 198) of the floor, and 19% (35 of 180) of the discharge phase. Overall potentially avoidable mortality was 41% (729 of 1780). Thirty-six percent (644 of 1,780) of the mortalities were coronary artery bypass grafting patients and 29% (188 of 644) of these were in the preoperative phase, with a mean predicted risk of 16%.

This analysis identifies the occurrence of potentially avoidable mortalities in the 4 hospital phases of care, with the largest absolute number of avoidable mortalities occurring in the preoperative phase. A focus on these phases of care provides significant opportunity for quality improvement initiatives. Utilizing phase of care mortality analysis stimulates surgeons and hospitals to develop and refine mortality reviews and provides a structured statewide platform for discussion, education, quality improvement, and enhanced outcomes.