Radioiodine-Associated Exacerbation of Graves' Orbitopathy in the Japanese Population: Randomized Prospective Study.

CONTEXT: Exacerbation of Graves' orbitopathy (GO) after radioiodine (RAI) therapy has been examined in some populations but has not been fully described in Japanese populations.

OBJECTIVE

The purpose of this study was to clarify the characteristics of GO exacerbation after RAI therapy and the effectiveness of low-dose prophylactic corticosteroid (PCS).

DESIGN AND

SETTING

This was a prospective randomized study in Tokyo, Japan.

PATIENTS: Between June 2011 and June 2012, 295 patients with Graves' disease with either inactive GO or no GO received RAI therapy. Of these, 147 received no PCS (PCS-Off group), whereas 148 received low-dose PCS (starting dose, 15 mg/day of prednisolone) for 6 weeks (PCS-On group). We used magnetic resonance imaging to thoroughly evaluate GO before and 1 year after RAI therapy.

MAIN OUTCOME MEASURES: Outcomes of GO 1 year after RAI therapy were determined.

RESULTS

GO exacerbation occurred in 29 patients (9.8%), and only 7 patients (2.4%) required ophthalmic treatment. No significant difference in the frequency of GO exacerbation was seen between the groups (PCS-On group: n = 18 [12.1%]; PCS-Off group: n = 11 [7.5%]; P = .17). Significant prognostic factors were identified as thyroid-stimulating antibody (by 100% linear increase: risk ratio, 1.15; 95% confidence interval, 1.07-1.24; P = .0003) and clinical activity score (≥1 vs 0: risk ratio, 6.40; 95% confidence interval, 2.17-19.7; P = .0009).

CONCLUSION

Exacerbation of GO after RAI therapy in the Japanese population appears less common than in other populations. Low-dose PCS did not produce a significant preventive effect and appeared insufficient. Patients presenting with risk factors would thus be recommended to receive higher-dose PCS.