Surgical mortality at low-volume hospitals varies according to type of surgery

Shelley Wood

April 10, 2002

Wed, 10 Apr 2002 21:00:00

Boston, MA - Medicare patients in the US who need to undergo certain cardiovascular or cancer surgeries are better off going to a hospital that performs a high volume of these procedures, a new study indicates. But, while the link between high volume and low mortality has been observed in the past, this latest research suggests that the relative importance of volume varies according to the type of procedure.

Dr John D Birkmeyer (Veterans Affairs Medical Center, White River Junction, VT) and colleagues published their study in the April 11, 2002 issue of the New England Journal of Medicine.

"In the absence of better information about surgical quality, patients undergoing many types of procedures can substantially improve their odds of survival by selecting a high-volume hospital near them," the authors write. They estimate that 20000 elderly men and women die each year undergoing one of the 14 procedures assessed in their study.

Hospital volume is an established - but not infallible - predictor of surgical mortality in patients undergoing high-risk surgery, but much of the data supporting this surrogate measure are out of date or based on regiona, not national, figures, Birkmeyer et al point out. Despite the dearth of solid evidence linking volume and outcome data for most surgical procedures, various consumer services have evolved to help patients with difficult decisions. The Washington, DC-based "Leapfrog Group," representing private and public insurers, encourages healthcare consumers to choose high-volume hospitals for surgical procedures and has set volume thresholds for certain types of operations that hospitals must meet to be recommended to patients. Online services like "Healthscope" are also emerging to help patients examine the volume and track record of hospitals near them.

Differences for cardiovascular procedures

By reviewing the national Medicare claims database, Birkmeyer et al were able to evaluate operative mortality (in-hospital or within 30 days of procedure) in relation to hospital volume in Medicare patients for 6 cardiovascular procedures and 8 cancer procedures. They report that a total of 2.5 million surgeries in these categories were conducted over the study period (1994-99). For all types of procedures, mortality rates decreased as hospital volumes increased. However, although some types of procedures, such as pancreatic resection, yielded absolute differences in adjusted mortality rates of 12% between the very-low- and very-high-volume centers, other procedures were associated with much smaller differences in mortality. Indeed, for coronary bypass grafting, the difference in adjusted mortality between highest- and lowest-volume centers was less than 2%.

Mortality rates for the six cardiovascular procedures

Procedure

Very-low-volume hospitals

Very-high-volume hospitals

6.1%
4.8%
9.9%
7.6%
16.1%
12.5%
2.0%
1.7%
6.1%
4.9%
7.8%
4.4%
To download table as a slide, click on slide logo below

Quality counts

In an editorial accompanying the Birkmeyer study, Dr Arnold M Epstein (Harvard School of Public Health) points out that private and public entities have 20 years' worth of studies on which to base policies limiting the number of surgeries conducted at lower volume hospitals. "After 2 decades of research, it is time to move ahead," he states.

Epstein suggests that while it is appropriate to increase the number of procedures at high volume centers and to educate physicians and patients to choose high-volume hospitals, the use of volume thresholds should initially be confined to urban centers. Broader scale policy changes should only be implemented after sufficient research has been shown to validate better outcomes at higher-volume centers. Lastly, he says, the "ultimate objective" of any initiative aimed at reducing operative deaths should not be to overload high-volume centers, but rather to reduce the gap in risk-adjusted morality between high- and low-volume hospitals.



Related links

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3. [HeartWire > News; Dec 10, 2001]


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