Background

In obese people with type 2 diabetes (T2D), bariatric surgery is cost-effective, but its economic impact in overweight but not obese people is uncertain.

Method

Two-year health and cost outcomes of an Australian randomized trial of gastric band (GB) surgery in overweight but not obese people (BMI 25 to 30kg/m²) with T2D were applied to a comparable sample of 254 participants of the U.S. National Health and Nutrition Examination Survey (NHANES) and combined with diabetes and cost outcomes of UKPDS risk engine simulations to determine incremental cost-effectiveness ratios (ICERs) for different treatment scenarios. Costs were inflated to 2015 U.S. dollar values and an ICER less than $50,000 considered cost-effective.

Results

The ICER for GB surgery after two years exceeded $90,000 but decreased to $52,000, $29,000 and $22,000 when its health benefits were assumed to endure for 5, 10 and 15 years respectively. Sensitivity analyses identified the utility gained from weight loss and, to a lesser degree, the costs of GB surgery, as critical determinants of cost-effectiveness. Conversely, better diabetes health outcomes and lower diabetes costs resulting from improvements in HbA1c, systolic blood pressure and cholesterol following GB surgery were relatively small and had little impact on its ICER.

Conclusions

GB surgery for overweight but not obese people with T2D appears to be cost-effective if weight loss endures for more than five years. Cost-effectiveness is highly dependent on the health utility gained from weight loss rather than from effects of surgery on diabetes outcomes.