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For people with severe obesity and diabetes, gastric bypass surgery offered the most bang for their buck over time, an economic modeling study found.

Over the course of 5 years, Roux-en-Y gastric bypass (RYGB) was associated with the most quality-adjusted life-years (QALY) gained -- mean 0.44 QALY (95% CI 0.21-0.86) -- compared with traditional medical therapy for the average patient with severe obesity (BMI of 40+) and comorbid type 2 diabetes, reported Chin Hur, MD, MPH, of Columbia University Irving Medical Center in New York City, and colleagues in .

When stratified by baseline diabetes severity, those with milder disease would gain even more quality of life back with RYGB:

• Mild disease: mean 0.59 QALY gained (95% CI 0.35-0.98)
• Moderate disease: mean 0.50 QALY gained (95% CI 0.25-0.88)
• Severe disease: mean 0.30 QALY gained (95% CI 0.07-0.79)

Using 2020 U.S. costs, the researchers also crunched the numbers for projected incremental cost-effectiveness ratios (ICERs) of each treatment. They deemed a treatment strategy to be cost-effective if the ICER was less than $100,000 per QALY gained.

Despite its upfront surgical costs over a 5-year period, RYGB was found to be cost-effective versus medical therapy for the general patient population with severe obesity and diabetes, with an ICER of $46,877 per QALY gained at an 83% probability of being the preferred treatment strategy. In addition, RYGB appeared to be even more cost-effective for those with milder diabetes:

• Mild disease: ICER of $36,479 per QALY gained at 73.7% probability
• Moderate disease: ICER of $37,056 per QALY gained at 85.6% probability
• Severe disease: ICER of $98,940 per QALY gained at 40.2% probability

Hur's group also pointed out that RYGB only became more cost-effective over time -- even 10 and 30 years out, at 98.1% and nearly 100% probability, respectively.

"Over a short time horizon, medical therapy may be preferred in those with severe type 2 diabetes at baseline because of the high cost of surgery and high rates of complications," they explained. "However, the benefits of RYGB, such as increased type 2 diabetes remission and greater sustained weight loss, were projected to offset these detriments over longer time horizons."

Aside from medical therapy -- which was comprised of lifestyle counseling, weight management, glucose monitoring, and drug therapies, defined by the American Diabetes Association and the STAMPEDE trial protocol -- the one other treatment strategy assessed in this study was another form of bariatric surgery: laparoscopic sleeve gastrectomy.

Although sleeve gastrectomy didn't offer quite as many QALY gained versus RYGB, it still performed better than medical therapy alone, increasing QALY gained by a mean of 0.31 (95% CI 0.13-0.66).

Because sleeve gastrectomy gained fewer QALYs and came at a higher cost per QALY gained, RYGB was ultimately deemed the "preferred" strategy for treating obesity and type 2 diabetes.

The only time sleeve gastrectomy was considered the preferred treatment was in a situation in which the cost of RYGB came at the maximum price tag ($34,442) performed in a patient with mild type 2 diabetes and sleeve gastrectomy was performed at the minimum price ($13,081) in a patient with severe type 2 diabetes.

Study Details

For this modeling simulation, Hur's group drew upon data from 1,000 nationally representative cohorts of 10,000 U.S. adults from the 1999 to 2018 cycles of the National Health and Nutrition Examination Survey. All participants had a BMI of 40 or higher with self-reported type 2 diabetes at baseline with an HbA1c of at least 6.5%. All patients were free of gastroesophageal reflux disease at the time of treatment.

Weight loss and regain projections with medical therapy were taken from the STAMPEDE trial, and surgery outcomes were projected using data from . Data for model inputs were also taken from other clinical trials, cohort studies, and national databases.

Quality of life and cost associated with each of these three treatment strategies included all cumulative direct medical costs, regardless of payer. Surgical strategies also took into account risks for minor and major complications, as well as mortality.

Of the final simulation cohort, 65.1% were women, with a mean age of 54.6; 16% had mild type 2 diabetes, 56% had moderate disease, and 28% had severe disease. The mean HbA1c at baseline was 7.4%, 31% were on insulin, and 77.6% were on an oral antidiabetic medication.

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