Trends in Hospital Volume and Operative Mortality for High-Risk Surgery

Study Questions:

What are the trends in the use of high-volume hospitals for major cancer resections and cardiovascular surgery, and concurrent trends in operative mortality rates associated with these procedures?


The investigators used national Medicare data to study patients undergoing one of eight different cancer and cardiovascular operations from 1999 through 2008. For each procedure, they examined trends in hospital volume and market concentration, defined as the proportion of Medicare patients undergoing surgery in the top decile of hospitals by volume per year. The authors used regression-based techniques to assess the effects of volume and market concentration on mortality over time, adjusting for case mix.


Median hospital volumes of four cancer resections (lung, esophagus, pancreas, and bladder) and of repair of abdominal aortic aneurysm (AAA) rose substantially. Depending on the procedure, higher hospital volumes were attributable to an increasing number of cases nationwide, an increasing market concentration, or both. Hospital volumes rose slightly for aortic valve replacement, but fell for coronary artery bypass grafting and carotid endarterectomy. Operative mortality declined for all eight procedures, ranging from a relative decline of 8% for carotid endarterectomy (1.3% mortality in 1999 and 1.2% in 2008) to 36% for AAA repair (4.4% in 1999 and 2.8% in 2008). Higher hospital volumes explained a large portion of the decline in mortality for pancreatectomy (67% of the decline), cystectomy (37%), and esophagectomy (32%), but not for the other procedures.


The authors concluded that although increased market concentration and hospital volume have contributed to declining mortality with some high-risk cancer operations, declines in mortality with other procedures are largely attributable to other factors.


This analysis of national Medicare data shows that the contribution of increasing hospital volume to declining mortality varied considerably according to procedure, with complex cancer resections associated with particularly strong relationships between volume and outcome, but there was considerably weaker association for cardiovascular procedures. It appears that for a small number of procedures associated with particularly strong direct volume–outcome relationships, such as pancreatectomy and esophagectomy, referral to high-volume centers should continue to be encouraged but for most high-risk procedures, strategies such as operating room checklists, outcome measurement with timely feedback programs, and collaborative quality improvement initiatives are likely to be more effective than just volume-based referral.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, Aortic Surgery, Interventions and Vascular Medicine

Keywords: Outcome Assessment (Health Care), Neoplasms, Endarterectomy, Carotid, Diagnosis-Related Groups, Pancreatectomy, Cystectomy, Esophagectomy, Urinary Bladder, Coronary Artery Bypass, Hospitals, High-Volume, Aortic Aneurysm, Abdominal, United States

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