Real-World Use of Subsidised Semaglutide in Icelandic Children With Obesity: A Nationwide Retrospective Cohort Study.

BACKGROUND: Real-world evidence of subsidised semaglutide in children with obesity is scarce. OBJECTIVES: To describe clinical outcomes (%IOTF30 change) in a nationwide cohort of Icelandic children prescribed subsidised semaglutide, describing outcomes across treatment settings and examining treatment response in children with and without neurodevelopmental disorders (ND). METHODS: Retrospective, population-based cohort study using longitudinal anthropometric measurements, March 20, 2021-June 6, 2025. Children aged ≥ 12 with grade 2 obesity were eligible for subsidised semaglutide under a universal reimbursement policy. Main outcomes were changes in %IOTF30 (BMI expressed as a percentage of the age- and sex-specific IOTF obesity threshold), modelled using piecewise linear mixed-effects regression. RESULTS: Among 113 participants (44% female; mean [SD] age 15.2 [2.0] years), pre-treatment %IOTF30 rose at 0.29 percentage points (pp)/month (95% CI, 0.26, 0.33). Semaglutide was associated with trajectory reversal at -0.86 pp/month (95% CI, -1.06 to -0.66); estimated reductions were 5.17 (95% CI, 3.98, 6.36) and 10.33 (95% CI, 7.96, 12.71) pp at six and 12 months. On-treatment slopes were numerically similar across settings but not interpretable as evidence of equivalent response. ND-status did not significantly modify treatment response among 56 Pediatric Obesity Center participants (interaction p = 0.83; underpowered). Overall, 63% achieved %IOTF30 reductions exceeding 10 pp. CONCLUSIONS: Semaglutide was associated with reversal of a longstanding upward weight trajectory in children with obesity. ND-status did not significantly modify treatment response; analysis was underpowered. Universal subsidisation policy enabled high treatment persistence and may inform reimbursement policy in other countries, though generalisability to settings without universal coverage remains uncertain.