Use of 90-day mortality does not change assessment of hospital quality after coronary artery bypass grafting in New York State

Objectives: Publicly reported postoperative 30-day mortality rates are commonly used to compare hospital quality after coronary artery bypass grafting. We sought to determine whether 90-day mortality rates, which are not publicly reported but better capture postdischarge mortality, are a better determinant of hospital performance. Methods: We performed a retrospective cohort analysis of 30- versus 90-day risk-standardized mortality rates at adult cardiac surgical centers in New York State from 2008 to 2014. Hospitals were classified as good or poor performing outliers at each time point based on the bounds of the 95% confidence interval around each hospital's predicted risk-standardized mortality rates determined via hierarchical models. The primary outcome was change in institutional performance via outlier classification from 30 to 90 days. Results: During the study period, 72,398 adults underwent a coronary artery bypass grafting procedure at 1 of 42 institutions. The risk-standardized mortality rates increased from 30 to 90 days at all institutions, with a median 30-day risk-standardized mortality rate of 2.16% (interquartile range, 0.69%) and median 90-day risk-standardized mortality rate of 3.69% (interquartile range, 1.00%). In using a 90-day instead of a 30-day metric, 3 hospitals changed outlier status. One hospital improved to a good from as expected performer, and 2 worsened to as expected from good performers. Conclusions: In a cohort of patients who underwent coronary artery bypass grafting surgery from 2008 to 2014 in New York State, use of a 90-day mortality metric resulted in a change in hospital quality assessment for a minority of hospitals. The use of 90-day mortality may not provide additional value when evaluating institutional performance for this population.