Background: To assess the cost-utility of gastric bypass versus usual care for patients with severe obesity in Spain.
Methods: We have implemented a discrete-event simulation model with two branches: one branch involves gastric bypass, thereby reducing patients' BMI, and another branch where patients do not undergo surgery. The model analyzes the emergence of comorbidities (stroke, coronary obstructive disease, diabetes, and breast cancer) associated with obesity during a lifetime horizon. The selected measure of effectiveness is health-related quality of life. Both costs and effects are discounted at 3 %. A probabilistic sensitivity analysis is also performed using second-order Monte Carlo simulation; acceptability curves for different time horizons were also calculated.
Results: Patients with gastric bypass result in a lifetime increase of 5.63 quality-adjusted life years (QALYs) (18.18 vs. 12.55 QALYs). In addition, because of the reduced spending associated with the treatment of various obesity-related comorbidities, final savings stand at 13,994 <euro>. The total cost of the intervention branch is close to half the cost of the non-intervention branch (17,431 vs. 31,425 <euro>).
Conclusions: Gastric bypass is an intervention that dominates over the option of not intervening when a lifetime horizon is considered.