Factors affecting the course of Graves’ Orbitopathy and poor response to glucocorticoid treatment followed by orbital radiotherapy.

Graves’ orbitopathy is a rare autoimmune disorder characterized by the inflammation of orbital tissues. The course of disease can be described in terms of its activity and severity. Aim: The aim of our study was to determine the factors affecting the activity and severity of Graves’ orbitopathy, as well as to identify the predictive factors of poor response to glucocorticoid treatment followed by orbital irradiation. Methods: We performed a prospective observational study of 214 patients with Graves’ orbitopathy who were divided into two groups depending on the treatment they had previously obtained for their Graves’ disease. They received i.v. methylprednisolone pulses followed by orbital radiotherapy. They were examined and had their TSH, TRAb and FT4 levels evaluated prior to treatment and after 1, 6 and 12 months. Results: A pre-treatment TRAb concentration higher by one unit (U/L) implied a mean increase in the relative risk of active orbitopathy by 4.7% (p = 0.0362). A TRAb concentration higher by one U/L 1 month after treatment implied a mean increase in the relative risk of moderate-to-severe and severe GO by 8.7% (p = 0.0167) 6 months after treatment. As regards poor response to treatment, patients with moderate-to-severe and severe Graves’ orbitopathy on admission carried a higher risk of being non-responders. Each point scored on the NOSPECS scale prior to treatment increased the relative risk of the patient being a non-responder by 30%. Conclusions: Patients with higher TRAb levels have a higher risk of active Graves’ orbitopathy and moderate-to-severe and severe Graves’ orbitopathy. Monitoring TRAb serum concentration in those patients is of great importance. Patients with more severe Graves’ orbitopathy carry a higher risk of being poor responders to immunosuppressive treatment. Therefore, careful monitoring of patients with Graves’ orbitopathy and their early referral to specialized centers is essential.