New Study Heralds Phentermine-Topiramate as Most Cost-Effective Antiobesity Agent for Adolescents

Phentermine-topiramate is the most cost-effective weight-loss treatment approved for adolescents, according to the results of a recent study published in JAMA Open Network. Although semaglutide resulted in more weight loss, the clinical benefits do not outweigh the higher cost, according to the study authors.

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“Our findings suggest that, as a weight-loss treatment for adolescents, the relatively low-cost phentermine-topiramate will both place smaller demands on health care budgets and offer better value for money,” the study authors wrote.

Childhood obesity increases the risk of adult obesity and serious comorbidities. Currently, more than 50% of children will have obesity by 35 years of age. As of January 2023, American Academy of Pediatrics (AAP) guidelines recommend children aged 12 years and older take antiobesity agents to prevent obesity in adulthood.

Unfortunately, many US insurance plans still do not provide coverage for weight loss drugs. There are still a lot of unknowns associated with this medication class, given the limited hard data supporting long-term efficacy, or studies evaluating post-treatment weight rebound.

Investigators conducted a modeling study of 10,000 pediatric patients aged 12 to 17 years with severe obesity to evaluate the cost-effectiveness of 4 antiobesity drugs (orlistat, liraglutide, semaglutide, and phentermine-topiramate) approved for pediatric use, relative to the cost efficacy of no treatment. Currently, orlistat and phentermine-topiramate cost between $1500 to $8500 annually, with semaglutide and liraglutide costing upward of $12,000.

The team measured cost effectiveness by quality-adjusted life-years (QALYs). Relative to no treatment, the cost effectiveness of phentermine-topiramate was $93,620 per QALY, which was within the average willingness-to-pay threshold ($100,000 to $150,000/QALY) of patients.

Semaglutide, which is the most effective anti-obesity drug with the highest QALYs, had an incremental cost-effectiveness ratio of $1,079,480 per QALY, costing significantly more than the willingness-to-pay threshold. And after further evaluation, the benefits for weight loss did not justify the cost of the product.

In addition, neither orlistat, which cost more than phentermine-topiramate and semaglutide, or liraglutide, which was not as effective as the 2 treatments, can ultimately be considered cost-effective weight loss agents.

AAP guidelines also recommend bariatric surgery for children aged 13 years and older with obesity, therefore, investigators conducted a sensitivity analysis to evaluate the cost-effectiveness of sleeve gastrectomy and gastric bypass surgeries. They also analyzed metformin hydrochloride in this assessment.

Neither type of bariatric surgery was as cost-effective as antiobesity medication, according to the study. In addition, metformin became the least costly agent when compared to the other 4 drugs, but it was also less effective than phentermine-topiramate, making the incremental cost-effectiveness ratio $64,000 per QALY. In addition, it is not FDA-approved for this indication or population and is not currently a plausible weight loss option for adolescents.

The sensitivity analysis also worked to highlight the potential cost effectiveness of medication that lasts into adulthood—in hindsight, investigators suggest that the current cost effectiveness ratios may not be high enough.

Study limitations include the absence of long-term efficacy data and having a majority female and White cohort. In addition, drug efficacy information came from different trials. Previous studies link semaglutide and liraglutide to the risk of thyroid cancer and phentermine-topiramate to birth defects; and the model did not capture all associated benefits of semaglutide.

“Further research is needed to determine long-term drug efficacy and how long adolescents continue treatment,” the authors concluded.

Reference

Mital S, Nguyen H. Cost-Effectiveness of Antiobesity Drugs for Adolescents With Severe Obesity. JAMA Netw Open. 2023;6(10):e2336400. doi:10.1001/jamanetworkopen.2023.36400