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Nationwide Study Confirms that Older Patients Who Need Certain High-Risk Surgeries Fare Better in More Experienced Hospitals

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Research Alert: April 10, 2002

Elderly patients who had any of 14 high-risk cardiovascular or cancer operations in hospitals performing a high volume of their particular procedure were more likely to survive than those who went to hospitals with a low volume of their type of surgery, according to a nationwide study sponsored by the Agency for Healthcare Research and Quality (AHRQ) and published in the April 11, 2002, issue of The New England Journal of Medicine (NEJM).

Going to the high-volume hospitals made the biggest difference for patients undergoing surgery for cancer of the pancreas. Only 4 percent of such patients at highest-volume hospitals died, compared to 16 percent at lowest-volume hospitals—a 12 percentage point difference. Death rates differed to a similar degree for patients undergoing surgery for cancer of the esophagus (8 percent at highest-volume hospitals versus 20 percent at lowest-volume ones).

The study also found that hospital volume was important for patients undergoing heart valve replacement, abdominal aneurysm repair, and surgery for lung, stomach or bladder cancer. For each these procedures, death rates at the highest-volume hospitals were between 2 percent to 5 percent lower than at the lowest-volume hospitals.

Hospital volume was least important for patients undergoing coronary artery bypass surgery, carotid endarterectomy (an operation to prevent stroke), and surgery for colon or kidney cancer. Death rates at the highest and lowest-volume hospitals for these procedures differed by less than 2 percent.

Each year in the United States more than 20,000 elderly patients die undergoing one of these 14 high-risk operations.

The research was led by John D. Birkmeyer, M.D., associate professor of surgery at Dartmouth Medical School. The nationwide study, which examined outcomes in approximately 2.5 million Medicare patients undergoing surgery between 1994 and 1999, was based on data from the national Medicare database and AHRQ's Nationwide Inpatient Sample from the Healthcare Cost and Utilization Project (HCUP). The researchers defined surgical volume as the average number of procedures performed by each hospital annually. The volume averages used to define high- and low-volume hospitals varied widely by procedure.

For more details, see "Hospital Volume and Surgical Mortality in the United States," by Dr. Birkmeyer, Andrea E. Siewers, M.P.H., Emily V.A. Finlayson, M.D., and others in the April 11, 2002, issue of NEJM. Dr. Birkmeyer also received funding from the Veterans Administration Health Services Research and Development Program.

Note to Editors: For interviews of Dr. Birkmeyer, please call the Public Affairs office of Dartmouth Medical School at (603) 650-1492.

For more information, please contact AHRQ Public Affairs, (301) 427-1364: Bob Isquith, (301) 427-1539 (


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