This cohort study examined Danish registry-based data on thyroid eye disease (TED) to determine the national incidence of TED, strabismus, strabismus surgery, and orbital decompression surgery.
The cohort consisted of 4.3 million adults included in the Danish National Patient Registry between 2000 and 2018. All diagnosed cases of TED were followed up to the occurrence of one of the TED sequelae studied (e.g., strabismus) or death, or until December 31, 2018, whichever came first.
During the time period studied, 21,967 cases of TED were noted, leading to a mean annual incidence rate of 5.0 per 100,000 person-years. Of the 4106 patients who had incident cases, 81.4% were women; 14.9% were euthyroid, 11.6% were hypothyroid, and 73.5% were hyperthyroid. The 4-year cumulative incidence rate of strabismus was 10% for strabismus, with higher rates seen in men (who also had higher rates of strabismus surgery). The 4-year cumulative incidence rate of decompression surgery was similar in men and women, about 5%.
The study is limited due to its inclusion criteria; all patients with an ICD-8 or -10 diagnosis of autoimmune hyperthyroidism or TED-related exophthalmos were included without validation. As well, the data come from a Danish population, so extrapolation of findings to a more heterozygous population is limited.
The incidence of TED presentation in larger populations is difficult to calculate. This study is one of the few to report these rates in a large population, comprising 4.3 million people. Establishing this information for all populations can help in future diagnosis and management.