Busy hospitals may not be best choice.

Since 1979, a host of studies has suggested that people in need of surgery should search out a hospital where a lot of surgeries of the required type are performed (SN: 7/17/99, p. 44). At a place such as that, the theory goes, the most experienced professionals will do the best job. A new study finds that this so-called volume benefit may be overrated for a common heart operation.

Physician Eric D. Peterson of the Duke Clinical Research Institute in Durham, N.C., and his colleagues reviewed the outcomes of 267,089 coronary artery bypass graft operations done at 439 hospitals during 2000 and 2001.

In the Jan. 14 Journal of the American Medical Association, the scientists report that the average death rate within 30 days of getting bypass surgery was 2.7 percent overall. In hospitals in which more than 450 such operations were performed annually, the average rate was only modestly lower, 2.4 percent. In hospitals doing fewer than 150 operations, the mortality rate was 3.5 percent.

Even this difference in average mortality rate might be deceptive. Compared with the busier hospitals, those hosting fewer surgeries treated a greater percentage of high-risk patients, the authors note. This apparently boosted those facilities' mortality rates among bypass-surgery patients.

Moreover, among patients under age 65, there was no significant difference in death rates, the authors report.

Peterson's team concludes that choosing a hospital for a particular operation shouldn't be based solely on the number of such surgeries performed there.

--N.S.