The impact of preoperative antiobesity medications on weight loss in adolescents undergoing metabolic and bariatric surgery - a COSMIC study.

BACKGROUND: While new medications are transforming the management of obesity, their association with outcomes in adolescents undergoing metabolic and bariatric surgery (MBS) is not clear. OBJECTIVES: The objective was to determine how preoperative prescription of antiobesity medications (AOMs) is associated with postoperative weight loss after MBS. SETTING: The study was conducted using data from 3 academic children's hospitals, spanning the period from March 2013 to September 2024. METHODS: This is a retrospective review in which demographics, obesity-related diseases, preoperative and postoperative weight and body mass index (BMI) were compared between patients who were treated preoperatively with topiramate or glucagon-like peptide-1 receptor agonists (GLP-1RAs) and those who were not. Statistical analyses included Wilcoxon rank-sum, Pearson's χ2, and Fisher's exact tests, plus 1:1 propensity score matching and multivariable linear regression sensitivity models adjusting for time-to-surgery. RESULTS: Of 324 patients, 22 were treated with topiramate and 30 with a GLP-1RA. Rates of obesity-related diseases were similar. Patients on GLP-1RA lost weight from first consultation to surgery (-2% BMI), while those on no medication gained (+1% BMI) and those on topiramate remained stable (0%, P = .023). There was no difference in weight/BMI at the time of surgery; however, patients pretreated with medications lost less weight than those not taking medications at 6 months (no medications: -20% BMI reduction; GLP-1RA: -18%; topiramate: -17%, P = .017) and 12 months (no medications -23% BMI reduction, GLP-1RA -15%, topiramate -17%, P = .015). From initial consultation to 12 months after surgery, the differences in weight loss between groups were not significant (P = .072). CONCLUSION: Preoperative exposure to topiramate or GLP-1RA was associated with less postoperative weight loss, despite similar starting weights/BMIs. Total weight loss from consultation through 12 months did not differ significantly between groups. These findings raise important questions regarding the use and timing of obesity management medications in relation to surgery for adolescents.