June 15, 2011

No fewer deaths in VA patients with bariatric surgery

Patients in Veterans Affairs study were older and higher risk

Seattle, WA—Use of bariatric surgery among older, severely obese patients was not associated with a decreased risk of death, according to the first study of long-term survival among high-risk patients who underwent bariatric surgery. The study, published in the June 15 issue of the Journal of the American Medical Association, was released early online to coincide with its presentation at the AcademyHealth Annual Research Meeting in Seattle.

Matthew L. Maciejewski, PhD, of the Durham VA Medical Center and Duke University, in Durham, NC, led the study with colleagues including Group Health Research Institute Associate Investigator David Arterburn, MD, MPH, who is also an affiliate assistant professor in internal medicine at the University of Washington School of Medicine. They conducted the study to determine whether bariatric surgery is associated with reduced mortality among predominantly older male high-risk patients at Veterans Affairs medical centers.

They examined mortality for 850 veterans who had bariatric surgery in January 2000 to December 2006 [average age 49.5 years; average body mass index (BMI) 47] and 41,244 nonsurgical controls (average age 54.7 years; average BMI 42) from the same 12 Veteran Integrated Service Networks; follow-up was through December 2008.

Eleven of the 850 surgical patients (1.29 percent) died within 30 days of surgery. The surgical patients had lower crude mortality rates than the nonsurgical controls (at one year, 1.5 percent vs. 2.2 percent; at two years, 2.2 percent vs. 4.6 percent; at six years, 6.8 percent vs. 15.2 percent). In unadjusted analysis, bariatric surgery was associated with reduced mortality. However, in further analysis that included 1,694 propensity-matched patients, bariatric surgery was not significantly associated with reduced mortality. Propensity matching is a statistical approach to compare patients who appear similar in many ways, except that one of the matched patients in each pair had the operation.

"Our results highlight the importance of statistical adjustment and careful selection of surgical and nonsurgical cohorts, particularly during evaluation of bariatric surgery according to administrative data,” the authors wrote.

“Previous studies claiming a survival benefit for bariatric surgery had limited clinical information to conduct detailed risk adjustment or matching,” they noted. “The survival differences between the bariatric surgery and control groups were modest in most previous studies, so the beneficial effects of surgery may have been attenuated if adjustment for confounders had been possible. We demonstrated that risk adjustment with regression analysis resulted in a significant association of surgery and survival that was reduced when equivalence in baseline characteristics improved via propensity matching in this high-risk patient group.”

As background, the research team explained, after decades of rapid increases, obesity incidence has stabilized in recent years. However, the period between 2000 and 2005 saw increases in higher-range BMIs: In those five years, the prevalence of patients with BMIs greater than 35 rose 39 percent; severe obesity (BMI greater than 40) rose 50 percent; and superobesity (BMI greater than 50) rose 75 percent.

“Obesity is difficult to treat, and bariatric surgery is the most effective means to induce weight loss for the severely obese,” the authors wrote. “Consequently, obesity surgery rates rapidly increased in tandem" with rises in higher-range BMIs.

The researchers add that even though bariatric surgery is not associated with reduced mortality among older male patients, many patients may still choose to undergo bariatric surgery, given the strong evidence for significant reductions in body weight and co-existing illnesses and improved quality of life.

Drs. Maciejewski and Arterburn co-authored the study with colleagues at the University of Texas Southwestern Medical Center and VA North Texas Health Care System, in Dallas; the University of Texas, in Arlington; Denver VA Medical Center and University of Colorado.

The Department of Veterans Affairs Health Services Research and Development Service’s Office of Research and Development supported this research. A Research Career Scientist award from the Department of Veterans Affairs supported Dr. Maciejewski.

VA Health Services Research and Development Service

The VA Health Services Research and Development Service pursues research that underscores all aspects of VA health care: patient care, care delivery, health outcomes, cost, and quality. The Service’s research also addresses critical issues for veterans returning home from Iraq and Afghanistan with conditions that may require care over their lifetimes.

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