Cost-Effectiveness of Pharmacotherapy for the Treatment of Obesity in Adolescents

Abstract

Importance: Antiobesity pharmacotherapy is recommended for adolescents ages 12 years and older with obesity. Several medications have been approved by the US Food and Drug Administration for adolescent use, but the most cost-effective medication remains unclear.

Objective: To estimate the cost-effectiveness of lifestyle counseling alone and as adjunct to liraglutide, mid-dose phentermine and topiramate (7.5 mg phentermine and 46 mg topiramate), top-dose phentermine and topiramate (15 mg phentermine and 92 mg topiramate), or semaglutide among adolescent patients with obesity.

Design, setting, and participants: This economic evaluation used a microsimulation model to project health and cost outcomes of lifestyle counseling alone and adjunct to liraglutide, mid-dose phentermine and topiramate, top-dose phentermine and topiramate, or semaglutide over 13 months, 2 years, and 5 years among a hypothetical cohort of 100 000 adolescents with obesity, defined as an initial body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) of 37. Model inputs were derived from clinical trials, published literature, and national sources. Data were analyzed from April 2022 to July 2023.

Exposures: Lifestyle counseling alone and as adjunct to liraglutide, mid-dose phentermine and topiramate, top-dose phentermine and topiramate, or semaglutide.

Main outcomes and measures: The main outcome was quality-adjusted life years (QALYs), costs (2022 US dollars), and incremental cost-effectiveness ratios (ICERs), with future costs and QALYs discounted 3.0% annually. A strategy was considered cost-effective if the ICER was less than $100 000 per QALY gained. The preferred strategy was determined as the strategy with the greatest increase in QALYs while being cost-effective. One-way and probabilistic sensitivity analyses were used to assess parameter uncertainty.

Results: The model simulated 100 000 adolescents at age 15 with an initial BMI of 37, of whom 58 000 (58%) were female. At 13 months and 2 years, lifestyle counseling was estimated to be the preferred strategy. At 5 years, top-dose phentermine and topiramate was projected to be the preferred strategy with an ICER of $56 876 per QALY gained vs lifestyle counseling. Semaglutide was projected to yield the most QALYs, but with an unfavorable ICER of $1.1 million per QALY gained compared with top-dose phentermine and topiramate. Model results were most sensitive to utility of weight reduction and weight loss of lifestyle counseling and top-dose phentermine and topiramate.

Conclusions and relevance: In this economic evaluation of pharmacotherapy for adolescents with obesity, top-dose phentermine and topiramate as adjunct to lifestyle counseling was estimated to be cost-effective after 5 years. Long-term clinical trials in adolescents are needed to fully evaluate the outcomes of pharmacotherapy, especially into adulthood.

Figure 1.. Microsimulation Model Overview

All patients began in the microsimulation model receiving treatment, either lifestyle counseling alone or adjunct to an antiobesity medication, ie, liraglutide, mid-dose phentermine and topiramate (7.5 mg phentermine and 46 mg topiramate), top-dose phentermine and topiramate (15 mg phentermine and 92 mg topiramate), or semaglutide. Every month of the simulation, patients could either continue receiving treatment or permanently discontinue treatment. Patients receiving lifestyle counseling adjunct to an antiobesity medication could experience an adverse event every month. Monthly change in body mass index was dependent on the specific treatment strategy, and all patients experienced weight gain after discontinuing any treatment. Death was determined from age- and sex-specific mortality rates.

Figure 2.. One-Way Sensitivity Analyses Over 5-Year Time Horizon

Mid-dose phentermine and topiramate indicates 7.5 mg phentermine and 46 mg topiramate; top-dose phentermine and topiramate, 15 mg phentermine and 92 mg topiramate; BMI, body mass index. Model parameters were independently varied across a set range while all other parameters were held constant at their mean value. The 10 model parameters with the largest effect on the incremental net monetary benefit relative to lifestyle counseling at a willingness-to-pay threshold of $100 000 per quality-adjusted life-year are shown. Parameters with the largest effect are located at the top, and parameters with the smallest effect are shown at the bottom. The incremental net monetary benefit represents the monetary value of an intervention for a given WTP threshold and is calculated as incremental quality-adjusted life-years × willingness-to-pay − incremental costs. An incremental net monetary benefit greater than $0 indicates the strategy is cost-effective compared with lifestyle counseling. The horizontal bars represent the range of incremental net monetary benefit when changing the value of each model parameter, and the color indicates which strategy was preferred. A change in the preferred strategy is shown with a colored vertical bar at the end of the horizontal bar. + and − at the end of the horizontal bars denote that the incremental net monetary benefit was calculated at the maximum and minimum value of the parameter, respectively. A tornado diagram was not generated for a time horizon of 13 months and 2 years, as the preferred strategy in most of the parameter ranges examined was lifestyle counseling.

Figure 3.. Cost-Effectiveness Acceptability Curves

The dashed line indicates the base case willingness-to-pay threshold of $100 000 per quality-adjusted life-year (QALY) gained.