Risk factors for thyroid-associated orbitopathy due to Graves' disease

Abstract

Background: Thyroid-associated orbitopathy (TAO) is the principal extrathyroidal manifestation of Graves' disease (GD). TAO is described as chronic inflammation of orbital and periorbital tissue. Environmental risk factors variably influence the development of TAO and risk factors vary with ethnicity and geographical region. Aims: To evaluate the clinical factors for TAO in patients with GD. Setting and Design: This was a hospital-based cross-sectional study done on consecutive 76 newly diagnosed patients of GD documented by thyroid 99mtechnetium-pertechnetate scan. Materials and Methods: Patients were subjected to a complete clinical workup and thyroid profile. The diagnosis of TAO was based on the criteria of Bartley and Gorman. Fifty-two TAO patients were compared with 24 non-TAO patients (controls) for risk. Statistical Analysis Used: All analyses were performed using SPSS software (version 21.0). Results: TAO was present in 52 (68%) of patients with GD. TAO was bilateral in 50 (96%) patients. Majority of the patients had mild orbitopathy (34, 65.4%) and none of the patients showed any signs of sight-threatening disease. Clinical activity score was active in 13.5% of the study group. There was significant female preponderance in TAO. Current smoking increased the risk of TAO (P = 0.023). Total triiodothyronine (T3) and mean intraocular pressure (IOP) in primary and upward gaze were significantly elevated at baseline in TAO patients. Braley's sign was seen in 30.7% of patients with TAO and in 8.3% of patients in the control group (P = 0.033). Current smoking, total T3 >4 ng/dl, and differential IOP >6 mmHg were found to be associated with the risk of TAO. Conclusion: TAO was clinically inactive and of mild severity in most cases. This study identified current smoking, total T3 >4 ng/dl, and differential IOP > 6mmHg as risk factors for TAO.