High-dose versus low-dose block-and-replace treatment for a first episode of Graves' Disease.

Abstract

Objective: The optimal treatment with antithyroid drugs (ATD) for a first episode of Graves' disease (GD) remains controversial. Methods Retrospective, two academic centres study of newly diagnosed GD between 1990 and 2022, treated with ATD in block-and-replace (B+R) regimen for at least 12 months and followed up for at least 1 year after ATD discontinuation or until disease relapse. Sixty patients received high-dose B+R (HD) with fixed ATD dose maintained during the study, and sixty patients low-dose B+R (LD) with lower ATD dose adjusted during the study. Results Baseline characteristics were similar in both groups. The point-prevalence of euthyroidism was not different between HD and LD (38% vs 47%, p=0.460 at 6 months, 69% vs. 82%, p=0.194 at 12 months, 70% vs. 78%, p=0.370 at 18 months, respectively). At 18 months, 27% HD vs. 38% LD (p=0.242) had thyroid eye disease. There were no differences in the number or type of ATD-related adverse events (AE) ( no AE 73% vs. 78%, p=0.707). LD received mean lower ATD dose (15.3 ± 4.2 vs. 30.0 ± 0.0 mg/day, p<0.001) and lower levothyroxine dose (72.6 ± 16.7 vs. 100.6 ± 24.5 µg/day, p<0.001). After a first course of ATD, 63% of HD patients and 60% of LD patients relapsed (p=0.707), after a median time [interquartile range] of 11.0 [18] vs. 7.0 [19] months (p=0.109) Conclusion We observed similar relapse rates in patients with a first episode of GD receiving up to 50% less ATD and 30% less levothyroxine dose than high-dose B+R regimen.