Risk Factors Associated with the Severity of Thyroid-Associated Orbitopathy in Korean Patients

PURPOSE The purpose of this study is to identify risk factors for severe thyroid-associated orbitopathy (TAO) and compressive optic neuropathy in Korean patients. METHODS This study was a retrospective comparative case series. All TAO patients who were first seen at our institution between 2005 and 2009 and who had follow-up periods of at least 6 months were included. Patients were divided into mild or moderate and severe TAO groups. Cases were also segregated based on the presence or absence of optic neuropathy. Demographics, smoking status, comorbidities, thyroid hormonal status, thyroid autoantibody levels, and clinical presentations were assessed. RESULTS A total of 99 patients (83 with mild to moderate courses and 16 with severe courses; 90 without optic neuropathy and 9 with optic neuropathy) were included in this study. On multiple logistic regression analysis, smoking status was a predictive risk factor for a severe course of TAO and the development of optic neuropathy (odds ratios = 6.57 and 10.00, respectively). Other factors such as age, gender, free T4 level, thyroid binding-inhibiting immunoglobulin, and a history of diabetes were not predictive of severe TAO or optic neuropathy. CONCLUSIONS Although various factors may influence the severity of TAO and the development of optic neuropathy, this study showed that smoking was a risk factor for severe TAO and the development of optic neuropathy. Therefore, it is important for patients with Graves' disease to refrain from smoking. Frequent and careful observation should also be performed in current smokers, as TAO patients who smoke are susceptible to a severe course and/or optic neuropathy.