Long-Term Follow-up of Graves Orbitopathy After Treatment With Short- or Long-Term Methimazole or Radioactive Iodine

Objective: The aim of this study was to compare long-term outcomes in terms of new onset or worsening of Graves orbitopathy (GO) in patients with Graves disease treated with different therapeutic modalities for hyperthyroidism.Methods: A total of 1163 patients with Graves disease were enrolled in this study; 263 patients were treated with radioiodine and 808 patients received methimazole (MMI) therapy for a median of 18 months, of whom 178 patients continued MMI for a total of 96 months (long-term methimazole [LT- MMI]). The thyroid hormonal status and GO were evaluated regularly for a median of 159 months since enrollment.Results: The rates of relapse, euthyroidism, and hypothyroidism at the end of follow-up were as follows: radioiodine treatment group: 16%, 22%, and 62%, respectively; short-term MMI group: 59%, 36%, and 5%, respectively; and LT-MMI group: 18%, 80%, and 2%, respectively. During the first 18 months of therapy, worsening of GO (11.5% vs 5.7%) and de novo development of GO (12.5% vs 9.8%) were significantly more frequent after radioiodine treatment (P <.004). Overall worsening and de novo development of GO from >18 to 234 months occurred in 26 (9.9%) patients in the radioiodine group and 8 (4.5%) patients in the LT- MMI group (P <.037). No case of worsening or new onset of GO was observed in patients treated with LT- MMI from >60 to 234 months of follow-up.Conclusion: Progression and development of GO were associated more with radioiodine treatment than with MMI treatment; GO may appear de novo or worsen years after radioiodine treatment but not after LT-MMI therapy.(c) 2023 Published by Elsevier Inc. on behalf of the AACE.