■ 学会名
The 22nd International Congress of Endocrinology (ICE2026) / The 99th Annual Congress of The Japan Endocrine Society (JES2026)

■ 発表日
2026/06/03

■ 筆頭演者
Emiri Morita
Department of Public Health, Health Management and Policy, Nara Medical University

■ 共同演者
Emiri Morita¹、Yuichi Nishioka¹,²、Kuniaki Ozaki²、Fumika Kamitani²、Takako Mohri²、Hiroki Nakajima²、Shin Urai²、Yukako Kurematsu²、Tomoya Myojin³、Tomoaki Imamura¹、Yutaka Takahashi²
1）Department of Public Health, Health Management and Policy, Nara Medical University
2）Department of Diabetes and Endocrinology, Nara Medical University Hospital
3）Department of Community Health & Preventive Medicine, Hamamatsu University School of Medicine

■ 発表形態
Poster

■ 受賞名
Poster Award

■ 要旨
Objective: To quantitatively evaluate the genetic and environmental factors associated with the risk of thyroid disease in Japanese individuals using claims data.
Methods: We used the DeSC claims database, identifying individuals who were continuously insured for the previous year and had no prior Graves’ disease or hypothyroidism. Graves’ disease was defined by antithyroid drug prescriptions, and hypothyroidism by levothyroxine replacement therapy. We calculated risk ratios for disease onset in groups with and without a family history at baseline. Additional analyses assessed the risk of disease onset when an individual’s spouse had a history of the respective disease.
Results: The study included 2,797,900 individuals (mean age 44.2±22.8 years; observation period 3.6±2.3 years). Of these, 0.14% had a family history of Graves’ disease and 0.25% of hypothyroidism. Compared with individuals without a family history, those with a family history had significantly higher risks for Graves’ disease (risk ratio 3.6, 95% confidence interval [CI] 1.3–9.8) and hypothyroidism (risk ratio 2.0, 95% CI 1.1–3.7). The risk ratios for Graves’ disease and hypothyroidism when the spouse had a history of the respective disease were 1.4 (95% CI 0.6–3.3) and 1.3 (95% CI 0.9–1.7), with no significant associations.
Discussion: Using large-scale Japanese claims data, we quantitatively demonstrated the association between family history and the risk of developing thyroid disease. These findings suggest that genetic factors may exert a stronger influence than environmental factors on disease risk in the Japanese population. A key novelty of this study is that it enabled an analysis previously difficult to perform: identifying individuals with affected family members before thyroid disease onset and tracking its incidence using a large claims database.