Risk Factors for the Relapse of Graves’ Disease Following Withdrawal of Antithyroid Drugs

Abstract

Objective: The treatment of Graves’ disease (GD) with antithyroid drugs (ATD) is associated with a risk of relapse. The rate and predictive factors of GD are controversial. This study aimed to assess the relapse rate after the withdrawal of ATD in patients with GD, as well as to identify its predictive factors. Material and Methods: This was a retrospective cohort study covering 35 patients with GD that were treated with ATD. Relapse was defined as the state when hyperthyroidism was detected after the withdrawal of medical therapy. Relapse was studied by establishing the survival curve according to Kaplan-Meier’s method. The Log-Rank test was used to compare the survival curves according to the clinical, biological, and therapeutic parameters of the patients. Results: The mean follow-up time after the withdrawal of ATD was 32.8±28.8 months. Relapse was observed in 13 patients (37%) after an average time of 7.8±8.8 months of ATD discontinuation. Factors associated with the risk of relapse were smoking (p=0.08), family history of thyroid disease (p=0.03), the presence of a triggering factor (p=0.004), FT4 level at the time of diagnosis at >2.3 times the normal range (p=0.002), thyroid-stimulating hormone level less than 0.76 mIU/L at three months after ATD withdrawal (p=0.05), and a benzylthiouracil dose of >125 mg/day at the time of ATD discontinuation (p=0.02). Conclusion: Relapse in patients with GD after the withdrawal of ATD is observed in almost a third of the patients. Identification of patients at a high risk of relapse is necessary to indicate radical treatment.