The Association Between Institutional Mortality After Coronary Artery Bypass Grafting at One Year and Mortality Rates at 30 Days.

Abstract Objective : To assess the association between the common quality metric of 30-day mortality with mortality at 60, 90 days and one year after coronary artery bypass grafting (CABG) Design : A retrospective cohort study, with multivariable logistic regression to assess association between mortality outcomes Setting : Hospitals participating in Medicare and reporting data within the Center for Medicare and Medicaid Services Limited Data Set between April 1, 2016 and March 31, 2017. Participants : 37,036 patients undergoing surgery at 394 hospitals Intervention : None Measurements and Main Results : On average, mortality rates were 1.0% to 3.1% for the top and bottom quartile of hospitals at 30 days. At one year, the top 25th percentile of hospitals had mortality rates averaging 3.9% while hospitals below the 75th percentile had mortality rates averaging 7.6%. 23% of hospitals in the top quartile at 30-days were no longer in the top quartile at 60 days. At one year, only 48% of hospitals that were in the top quartile at 30-days remained in the top quartile. The correlation between mortality rates at 30 days and the reported time points was assessed using Spearman's rho. The R value between mortality at 30-days and mortality at 1 year was 0.53 which improved to 0.7 and 0.76 at 60 and 90 days. Conclusions : Mortality at 30-days correlated poorly with mortality at 1 year. Hospitals that were high or low performing at 30-days were frequently no longer within the same performance group at one year.