Estimated Cost-effectiveness of Medical Therapy, Sleeve Gastrectomy, and Gastric Bypass in Patients With Severe Obesity and Type 2 Diabetes

Abstract

Importance: Bariatric surgery is recommended for patients with severe obesity (body mass index ≥40) and type 2 diabetes (T2D). However, the most cost-effective treatment remains unclear and may depend on the patient's T2D severity.

Objective: To estimate the cost-effectiveness of medical therapy, sleeve gastrectomy (SG), and Roux-en-Y gastric bypass (RYGB) among patients with severe obesity and T2D, stratified by T2D severity.

Design, setting, and participants: This economic evaluation used a microsimulation model to project health and cost outcomes of medical therapy, SG, and RYGB over 5 years. Time horizons varied between 10 and 30 years in sensitivity analyses. Model inputs were derived from clinical trials, large cohort studies, national databases, and published literature. Probabilistic sampling of model inputs accounted for parameter uncertainty. Estimates of US adults with severe obesity and T2D were derived from the National Health and Nutrition Examination Survey. Data analysis was performed from January 2020 to August 2021.

Exposures: Medical therapy, SG, and RYGB.

Main outcomes and measures: Quality-adjusted life-years (QALYs), costs (in 2020 US dollars), and incremental cost-effectiveness ratios (ICERs) were projected, with future cost and QALYs discounted 3.0% annually. A strategy was deemed cost-effective if the ICER was less than $100 000 per QALY. The preferred strategy resulted in the greatest number of QALYs gained while being cost-effective.

Results: The model simulated 1000 cohorts of 10 000 patients, of whom 16% had mild T2D, 56% had moderate T2D, and 28% had severe T2D at baseline. The mean age of simulated patients was 54.6 years (95% CI, 54.2-55.0 years), 61.6% (95% CI, 60.1%-63.4%) were female, and 65.1% (95% CI, 63.6%-66.7%) were non-Hispanic White. Compared with medical therapy over 5 years, RYGB was associated with the most QALYs gained in the overall population (mean, 0.44 QALY; 95% CI, 0.21-0.86 QALY) and when stratified by baseline T2D severity: mild (mean, 0.59 QALY; 95% CI, 0.35-0.98 QALY), moderate (mean, 0.50 QALY; 95% CI, 0.25-0.88 QALY), and severe (mean, 0.30 QALY; 95% CI, 0.07-0.79 QALY). RYGB was the preferred strategy in the overall population (ICER, $46 877 per QALY; 83.0% probability preferred) and when stratified by baseline T2D severity: mild (ICER, $36 479 per QALY; 73.7% probability preferred), moderate (ICER, $37 056 per QALY; 85.6% probability preferred), and severe (ICER, $98 940 per QALY; 40.2% probability preferred). The cost-effectiveness of RYGB improved over a longer time horizon.

Conclusions and relevance: These findings suggest that the effectiveness and cost-effectiveness of bariatric surgery vary by baseline severity of T2D. Over a 5-year time horizon, RYGB is projected to be the preferred treatment strategy for patients with severe obesity regardless of baseline T2D severity.

Figure 1.. Microsimulation Model Overview

BMI indicates body mass index; RYGB, Roux-en-Y gastric bypass; SG, sleeve gastrectomy.

Figure 2.. Cost-effectiveness Acceptability Curves Over 5-Year Time Horizon

QALY indicates quality-adjusted life-year; RYGB, Roux-en-Y gastric bypass; SG, sleeve gastrectomy.

Figure 3.. Cumulative Health Care Costs Stratified by Type, Excluding Initial Cost of Surgery

RYGB indicates Roux-en-Y gastric bypass; SG, sleeve gastrectomy.