For some surgeries, high volume = better outcomes

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.

Going to the high-volume hospitals made the biggest difference for patients undergoing surgery for cancer of the pancreas. Only 4% of such patients at highest-volume hospitals died, compared to 16% at lowest-volume hospitals. Death rates differed to a similar degree for patients undergoing surgery for cancer of the esophagus (8% at highest-volume hospitals vs. 20% 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 of these procedures, death rates at the highest-volume hospitals were between 2% to 5% lower than at the lowest-volume hospitals. Hospital volume was least important for patients undergoing coronary artery bypass surgery, carotid endarterectomy, and surgery for colon or kidney cancer.

Death rates at the highest- and lowest-volume hospitals for these procedures differed by less than 2%. 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, MD, associate professor of surgery at Dartmouth Medical School in Hanover, NH. 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.

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.