Clinical Characteristics of Users of Weight Loss Drugs: Population‐Based Case–Control Study

OBJECTIVES: To investigate the clinical characteristics of weight loss drugs (WLDs) users in Norway. DESIGN: Nested population-based case-control study. SETTING: Nationwide healthcare registries with data on dispensed medications and healthcare diagnoses. PARTICIPANTS: Individuals aged 18-74 years initiating WLDs during 2023-2024, categorised by drugs: semaglutide (only Wegovy), liraglutide (only Saxenda), tirzepatide, bupropion-naltrexone or orlistat. Each WLD user was matched with five age- and sex-matched population controls. MAIN OUTCOME MEASURES: Comorbidities diagnosed in the 2 years preceding initiation of WLD use and comedications dispensed in the preceding year, analysed using conditional logistic regression. RESULTS: 150 036 individuals initiated semaglutide, 4603 liraglutide, 3596 tirzepatide, 31 172 bupropion-naltrexone and 1411 orlistat. Among WLD users, 71%-78% were registered with at least one comorbidity, compared with 49%-51% in controls. Nineteen percent to 24% of WLD users had four or more comorbidities. Hypertension was observed among 32%-38% of WLD users versus 17%-20% of controls; hyperlipidaemias: 20%-24% versus 12%-15%; sleep apnoea: 7%-11% versus 2%-3%; back pain: 15%-20% versus 10%-11%; opioids: 24%-30% versus 13%-15%; antidepressants: 20%-24% versus 10%-11%. Having only a basic level of education (≤ 10 years) was more common among WLD users than among controls (20%-28% vs. 17%), except for tirzepatide users, where the education level distribution was as for controls. CONCLUSIONS: WLD use is rapidly increasing, with users often having complex comorbidities. Understanding these patterns helps ensure that medications are used as intended. Like other countries with universal health systems, Norway must address the high cost of obesity treatments and mitigate health disparities to ensure access for those most likely to benefit.