Trends in Pharmacological, Radioactive Iodine, and Surgical Treatments for Hyperthyroidism in Japan: A Decade-Long Nationwide Claims-Based Analysis (2014-2023).

OBJECTIVE: To investigate the nationwide trends in pharmacological, radioactive iodine (RAI), and surgical treatments for hyperthyroidism in Japan from 2014 to 2023. METHODS: Annual sex- and age-stratified data on methimazole (MMI), propylthiouracil (PTU), potassium iodide (KI), RAI therapy, and thyroidectomy were extracted from the National Database of Health Insurance Claims (NDB). Crude and age-adjusted counts and rates per 1,000 (drugs) or 100,000 (RAI and surgery) person-years were calculated for each year. The annual trends were analyzed using linear and Poisson regression models. RESULTS: The cross-sectional distributions strongly reflected the female reproductive life stages. Notably, RAI therapy charges exhibited a bimodal peak distribution in females (25-29 and 45-49 years), whereas thyroidectomy peaked at 30-34 years, coinciding with the intervening childbearing period. Longitudinally, age-adjusted MMI and KI prescriptions and surgeries increased significantly (P ＜0.0001), whereas PTU prescriptions and RAI therapy declined (P ＜0.0001). Subgroup analyses revealed distinct age-dependent shifts, with MMI and KI use increasing across most age groups, particularly among individuals aged ≥90 years. PTU use showed divergent trends by sex, decreasing among males, but increasing among older females, particularly those aged ≥90 years. Surgical interventions increased mainly among older adults, whereas RAI therapy declined across most age groups. CONCLUSION: Over the past decade, hyperthyroidism management in Japan has shifted toward MMI consolidation, expanded KI use in the super-elderly population, declining RAI therapy in broad-aged populations, and increasing surgery in older adults. These age-dependent treatment shifts reflect the evolving clinical practice and therapeutic challenges posed by a rapidly aging society.