April 29, 2016
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Later onset, longer duration of Graves’ hyperthyroidism, smoking predictors for Graves’ orbitopathy

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In patients with Graves’ hyperthyroidism, predictive factors for Graves’ orbitopathy include older age of disease onset, longer disease duration and smoking, according to recent findings in a large prospective study.

Jwu Jin Khong, MD, an ophthalmologist at the University of Melbourne and The Royal Victorian Eye and Ear Hospital in Victoria, Australia, and colleagues evaluated 1,042 patients with Graves’ hyperthyroidism recruited from endocrinology and ophthalmology clinics and private practices across Victoria and South Australia between 2009 and 2013. Those with Graves’ orbitopathy were designated cases (n = 604); those without, controls (n = 438).

JwuJin Khong

Jwu Jin Khong

Patients with Graves’ orbitopathy exhibited symptoms identified using the Vancouver Orbitopathy Rule questionnaire, including red eyes, lid swelling, eye protrusion and stare, and blurred vision. Using multiple logistic regression, researchers evaluated the following variables in terms of their effect on orbitopathy: patient age at recruitment, duration of Graves’ hyperthyroidism, family history of the disease, presence of other autoimmune diseases, ethnicity and smoking status. The study’s primary outcome was risk factors for Graves’ orbitopathy; dysthyroid optic neuropathy was a secondary outcome.

Researchers found that for each decade increase in age at Graves’ hyperthyroidism diagnosis, there was a 17% increase in the odds of orbitopathy (P = .002). For each year increase in disease duration at baseline, there was a 7% increase in the odds of developing orbitopathy (P < .001). Current smokers had increased odds for orbitopathy (OR = 2.22) as did ex-smokers (OR = 2.07) compared with nonsmokers (P < .001). Patients prescribed antithyroid medication had an 86% lower odds of developing orbitopathy vs. patients not on antithyroid medication (OR = 0.14; 95% CI, 0.06-0.34). Predictors of dysthyroid optic neuropathy included earlier age of orbitopathy onset, smaller palpebral aperture, moderate to severe restriction of oculomotility, strabismus and active orbitopathy. The odds of neuropathy increased by 58% for every decade increase in age of orbitopathy onset.

“In our case-control study, we were able to demonstrate that the age of onset of Graves’ hyperthyroidism, duration of Graves' disease and smoking (both current and past) were risk factors for Graves’ orbitopathy, whereas use of antithyroid medication was negatively related to Graves' orbitopathy,” Khong told Endocrine Today. “We have also found that older patients [with] restriction of ocular movement, strabismus and active Graves’ orbitopathy are at higher risk of dysthryoid optic neuropathy and may benefit from early medical assessment and intervention to prevent the onset of this sight-threatening complication.” – by Jennifer Byrne

Disclosure: The researchers report no relevant financial disclosures.