Endocrine Abstracts

Background: Little is known about the long-term outcome of the thyroid function in Graves’ disease in a large epidemiological setting.

Objective: The aim was to evaluate the long-term outcome of the thyroid function in patients diagnosed with Graves’ disease in Denmark in the period 1995-2018. Our research objectives were to investigate the incidence of disease, use of antithyroid drugs, radioactive iodine, thyroidectomy and levothyroxine during follow-up, and thyroid related drug usage at end of follow-up.

Methods: This was a nationwide register-based cohort study. Data from the Danish National Patient Register and the Danish National Prescription Register were retrieved. Patients ≥18 years of age with an ICD-10 diagnosis code for Graves’ disease or thyroid associated ophthalmopathy were included. The patients were followed until end of study, migration, or death.

Results: 43,579 individuals were included and followed for median 9.7 years [4.2-15.2]. The annual incidence of Graves’ disease declined from 29.5/100,000 in 1995 to 8.3/100,000 in 2018. Drug prescription data were available in 33,096 patients, of whom 5.4% underwent thyroidectomy. Antithyroid drugs were used by 10.6% among individuals followed for ≥20 years. At end of follow-up, 43.6% of patients were without any thyroid related drugs. Spontaneous conversion into hypothyroidism occurred in 8.1%.

Conclusions: Large differences in the long-term outcome of the thyroid function in Danish patients with Graves’ disease were shown. A minority of patients underwent ablative treatment. Nearly half of the patients achieved disease remission at end of follow-up, while approximately 8% converted into hypothyroidism spontaneously during the study period.