Procedural volume as a marker of quality for cabg surgery

Abstract

THE ASSOCIATION BETWEEN HOSpitals’ coronary artery bypass graft (CABG) surgery volume and outcome has been the subject of multiple investigations. Based on these studies, the Center for Medicare & Medicaid Services (CMS) and the Leapfrog Group have proposed using hospital volume as an indicator of CABG quality. Prior studies of the association between volume and outcome, however, generally have been based on administrative data sources, have reflected selected patient populations, and often have not adequately accounted for patient case mix, patient clustering, and other methodological concerns. Before hospital surgery volume is accepted as a standard quality metric, further research into issues related to both analysis and policy implication is warranted. We undertook a contemporary examination of the association between hospital CABG procedural volume and outcome using clinical data available from the Society of Thoracic Surgeons (STS) National Cardiac Database. Specifically, we considered whether hospital CABG volume was associated with operative mortality after accounting for patient case mix. Second, we examined the extent to which patient clustering within centers and site variance issues affected this association. Third, we determined how the association varied as a function of patient age and predicted surgical risk. Fourth, we determined whether the association between hospital volume and outcome was influenced by individual surgeon volume. Finally, we investigated the potential health policy implications of using hospital volume as a quality indicator. This included determining the ability of hospital volume to discriminate high-mortality outliers, as well as investigating the potential number of lives saved if low-volume centers were systematically closed. METHODS Data Source The STS National Cardiac Database was established in 1989 to report surgical outcomes following cardiothoracic surgical procedures. The database cur-