The association between methimazole tapering and intractable Graves' disease in children.

Background: The aim of this study was to find predictive factors for intractable Graves' disease (GD).

Methods: Ninety-three GD patients who visited two pediatric endocrinology clinics from March 2009 to August 2019 were involved in this study. Data were collected on the methimazole (MZ) dosages prescribed from their first visits to their fifth visits. The amount of tapered dosage was presented as a "tapering velocity" (dosage difference (mg/m²)/follow-up interval (months)). The relationship between the tapering velocity and the remission rate of GD was analyzed. Remission of GD was defined as having a total period of MZ treatment less than 5 years with no relapse after MZ withdrawal for at least more than a year.

Results: Of 93 patients diagnosed with GD, 26 patients (28.0%) were classified as the "remission group" and 67 (72.0%) were classified as the "intractable group." The frequency of goiter was significantly higher in the intractable group (p = 0.031). Multivariate logistic analysis revealed that the tapering velocity change from the first to the fifth visit significantly influenced the risk of intractable GD: odds ratio (OR) = 0.598, 95% confidence interval (CI) 0.413-0.865, p = 0.006. An accompanying goiter at the time of diagnosis (OR = 4.706 95% CI 1.315-16.847, p = 0.017) and thyroid stimulation hormone receptor antibody titer (OR = 1.032 95% CI 1.002-1.062, p = 0.034) were also found to be independent factors associated with intractable progress in GD.

Conclusion: Difficulty in tapering the MZ dosage in the first 4 months of treatment was an independent predicting factor for intractable GD.