Impact of public reporting of coronary artery bypass graft surgery performance data on market share, mortality, and patient selection.

Background: The impact of publicly reporting risk-adjusted outcomes for hospitals and surgeons remains controversial, with particular concern about unintended consequences. Objectives: We evaluated the impact of 3 reports from the voluntary California CABG Mortality Reporting Program (CCMRP) on hospital market share, hospital mortality, and patient selection for coronary artery bypass graft (CABG) surgery. Research Design and Participants: We analyzed data from January 2000 to December 2005 for all patients receiving isolated CABG surgery in California. We compared hospital groups based on their quality classification, including low-mortality outliers ("better"), high-mortality outliers ("worse"), and nonoutliers, as well as participation in the CCMRP. Measures: We compared changes in market share, risk-adjusted mortality, and hospital caseload of high-risk patients for isolated CABG surgeries before and after the public release of 3 CCMRP reports (July 2001, August 2003, and February 2005). Results: Low-mortality outlier hospitals experienced significantly increased market share for isolated CABG surgery in the first 6 months after the public release of the CCMRP reports (relative change in adjusted mean market share = 8.9%, P = 0.002). We found no evidence to suggest reduced risk adjusted mortality after the release of the CCMRP reports, but high-mortality outlier hospitals, on average, operated on less sick patients (relative change in mean expected mortality = 25%, P = 0.02). Conclusions: The release of public CABG hospital performance reports in California was associated with increased volume at low-mortality hospitals, and may have reduced referrals of high-risk patients to high-mortality hospitals (or risk avoidance).