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Outcomes/Effectiveness Research

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Researchers examine the influence of hospital surgery volume, procedure type, and patient age on surgical risk

Previous research has shown that patients who undergo surgery at hospitals that conduct a low volume of such surgeries are less likely to have good outcomes compared with those treated at high-volume hospitals. A recent study goes a step further to conclude that employers and health care purchasers could prevent many surgery-related deaths by requiring hospital volume standards for high-risk procedures such as coronary artery bypass graft surgery and esophagectomy. A second study concludes that population-based deaths from elective high-risk surgery among older adults are considerably higher than typically reported in case series and trials. Both studies on surgical risk, which are summarized here, were supported in part by the Agency for Healthcare Research and Quality (HS10141) and led by John D. Birkmeyer, M.D., of the Department of Veterans Affairs Medical Center.

Birkmeyer, J.D., Finlayson, E.V., and Birkmeyer, C.M. (2001, September). "Volume standards for high-risk surgical procedures: Potential benefits of the Leapfrog initiative." Surgery 130, pp. 415-422.

Despite the generally poorer outcomes of patients who undergo surgical procedures at hospitals that conduct a low volume of such procedures (low-volume hospitals, LVHs) compared with high-volume hospitals (HVHs), very few efforts have been made to regionalize certain procedures and move patients to HVHs. An exception is an initiative by the Leapfrog Group, comprised of several large employers and health care purchasers in the United States, who collectively employ over 20 million people in the Midwest and on the Pacific Coast. The Leapfrog Group soon will require hospitals caring for their employees to meet volume standards for five high-risk procedures: coronary artery bypass graft (CABG) surgery, abdominal aortic aneurysm (AAA) repair, coronary angioplasty, esophagectomy (for esophageal cancer), and carotid endarterectomy (CEA).

This study estimated that with full implementation nationwide, the Leapfrog volume standards would save 2,581 lives. Volume standards would save the most lives with CABG (1,486), followed by AAA repair (464), coronary angioplasty (345), esophagectomy (186), and CEA (118). If only 50 percent of patients estimated to be taken care of at metropolitan LVHs were moved to HVHs, 1,290 total lives would be saved. Similarly, if the volume standards were only half as effective as baseline assumptions, 1,290 lives would be saved.

In any case, the number of lives potentially saved remains substantial enough for the Centers for Medicare & Medicaid Services (formerly the Health Care Financing Administration or HCFA), a Leapfrog liaison, to explore volume standards for the Medicare population. These findings are based on an analysis of data from AHRQ's Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample and other sources. The researchers estimated the total number of each of the five procedures performed each year in U.S. metropolitan hospitals. They then projected the effectiveness of volume standards (in terms of relative risks of mortality) for each procedure by using data from a published structured review.

Finlayson, E.V., and Birkmeyer, J.D. (2001, July). "Operative mortality with elective surgery in older adults." Effective Clinical Practice 4, pp. 172-177.

Surgeons understandably tend to be optimistic about the benefits of surgery and typically underestimate surgical risks. Data on surgical mortality usually represent outcomes for experienced tertiary care centers and carefully selected patients, which also result in somewhat overly optimistic risk estimates. To help patients make informed decisions about whether to undergo elective high-risk surgery, surgeons and primary care physicians need more realistic estimates of surgical risks. Toward this end, these investigators used the national Medicare database to examine operative mortality (death within 30 days of the operation or before discharge) in 1.2 million Medicare patients who were hospitalized between 1994 and 1999 for major elective surgery (six cardiovascular procedures and eight major cancer resections).

Overall, mortality risk increased with age. Operative mortality for patients 80 years of age and older was more than twice that of patients 65 to 69 years of age. Operative mortality also varied by procedure. Procedures associated with relatively low mortality included carotid endarterectomy (1.3 percent of patients) and nephrectomy (2.3 percent). Overall mortality was greater than 10 percent for other procedures, such as mitral valve replacement (10.5 percent), esophagectomy (13.6 percent), and pneumonectomy (13.7 percent).

These mortality rates were higher than those reported in clinical trials and surgical texts. Although they give some indication of surgical risk, they are only a starting point. Doctors who counsel patients about the risks of elective surgery need to consider other factors. Besides age, other patient characteristics—such as coexisting illnesses, whether the surgery is a reoperation, and urgency of the operation—should be considered. Specific details about the procedure as well as its complexity also can modify risk. Finally, a patient's risk of death from surgery is influenced by where the operation is performed and who performs the surgery.

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