Assessment of Operator Variability in Risk-Standardized Mortality Following Percutaneous Coronary Intervention: A Report From the NCDR

Abstract

Objectives: This study sought to determine variability and stability in risk-standardized mortality rates (RSMR) of percutaneous coronary intervention (PCI) operators meeting minimum case volume standards and identify differences in case mix and practice patterns that may account for RSMR variability.

Background: RSMR has been suggested as a metric to evaluate the performance of PCI operators; however, variability of operator-level RSMR and the stability of this metric over time among the same operator are unknown.

Methods: The authors calculated mean RSMRs for PCI operators with average annual volume of ≥50 cases in the National Cardiovascular Data Registry CathPCI Registry. Funnel plots were used to account for operator case volume. Demographic, clinical, and treatment variables of patients treated by operators with outlying high or low RSMRs (identified by RMSR greater than or less than 2 σ above or below the mean [analogous to 2 SD], respectively) were compared with nonoutlier operators. RMSR stability was assessed by calculating average annual operator RMSR during the study period and by determining if operators were consistently classified into RMSR categories in each year.

Results: Between October 1, 2009, and September 30, 2014, a total of 2,352,174 PCIs were performed at 1,373 hospitals by 3,760 operators. Of these, 242 operators (6.5%) had RSMR >2 σ above the mean and 156 operators (4.1%) had RSMR >2 σ below the mean. Both high and low RSMR outlier operators treated patients with lower expected mortality risk, compared with nonoutlier operators. There was significant instability in annual operator RMSR during the study period.

Conclusions: There is significant variability in risk-standardized PCI mortality among U.S. operators meeting minimum volume standards that is not explained by case mix or procedure characteristics. Operator RMSR was unstable from year to year, thus limiting its utility as a sole performance measure for PCI quality.

Keywords: coronary artery disease; percutaneous coronary intervention; quality measure; risk standardized mortality rate.