Bariatric surgery among older, high-risk patients not associated with reduced mortality

"Obesity incidence has stabilized after decades of rapid increases, whereas the prevalence of patients with a body mass index [BMI] greater than 35 increased 39 percent between 2000 and 2005, the prevalence of severe obesity (BMI greater than 40) increased 50 percent, and the prevalence of superobesity (BMI greater than 50) increased 75 percent. Obesity is difficult to treat, and bariatric surgery is the most effective means to induce weight loss for the severely obese. Consequently, obesity surgery rates rapidly increased in tandem," according to background information in the article. "To date, no study to our knowledge has examined the long-term survival of high-risk patients who underwent bariatric surgery."

Matthew L. Maciejewski, Ph.D., of the Durham VA Medical Center, Durham, N.C., and colleagues conducted a study to determine whether bariatric surgery is associated with reduced mortality among predominantly older male high-risk patients at Veterans Affairs medical centers. Mortality was examined for 850 veterans who had bariatric surgery in January 2000 to December 2006 (average age 49.5 years; average BMI, 47.4) and 41,244 nonsurgical controls (average age 54.7 years; average BMI 42.0) from the same 12 Veteran Integrated Service Networks; the follow-up was through December 2008.

Eleven of 850 surgical case patients (1.29 percent) died within 30 days of surgery. The surgical case patients had lower crude mortality rates than the nonsurgical controls (at 1 year, 1.5 percent vs. 2.2 percent; at 2 years, 2.2 percent vs. 4.6 percent; at 6 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 (using a statistical approach to compare patients who appear to be "similar" in many ways, except for one of the matched patients having had the operation), bariatric surgery was not significantly associated with reduced mortality.

"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. Previous studies claiming a survival benefit for bariatric surgery had limited clinical information to conduct detailed risk adjustment or matching. 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," the authors write.

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.

More information: JAMA. 2011;305[23]2419-2426.

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