The prevalence of severe obesity among nonelderly U.S. men and women increased by 114 percent between 1991 and 1999. Dietary therapy, even together with exercise and behavior therapy, is rarely successful in these patients, who typically have a body mass index (BMI) of more than 40 kg/m2. BMI is body weight in kilograms divided by height in meters squared. A person who has a BMI of 25 or less is considered to be at normal weight.
Given the numerous health risks of severe obesity, gastric bypass (which divides the stomach to form a small gastric pouch) has the potential to improve health dramatically at a reasonable cost, concludes a study supported by the Agency for Healthcare Research and Quality (National Research Service Award training grant T32 HS00083).
Benjamin M. Craig, M.S., of the University of Wisconsin, and Daniel S. Tseng, M.D., M.S., of Washington Hospital Center, performed a cost-effectiveness analysis of gastric bypass versus no treatment for relatively healthy women and men (aged 35 to 55 years) with a BMI between 40 and 50 kg/m2, for whom conservative therapies such as diet, exercise, behavior therapy, and medication, had been unsuccessful. Although gastric bypass was associated with the risk of postoperative death and complications, it was also estimated to result in a mean 58 percent loss of excess weight (above a BMI of 22) 5 years later.
In all risk subgroups, the cost-effectiveness ratios of gastric bypass versus no treatment were favorable, at less than $50,000 per quality-adjusted life year (QALY). The ratios ranged from about $5,000 to $16,000 per QALY for women and from about $10,000 to $35,600 per QALY for men, depending on age and initial BMI. However, because the reduction in lifetime medical cost was no greater than the cost of treatment in any subgroup, gastric bypass was not cost-saving from the payer perspective. This study did not include severely obese patients with chronic medical conditions for whom the surgical risks, as well as the benefits of weight loss, would be greater.
More details are in "Cost-effectiveness of gastric bypass for severe obesity," by Mr. Craig and Dr. Tseng, in the October 15, 2002, American Journal of Medicine 113, pp. 491-498.
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