Dynamic Risk Model for the Medical Treatment of Graves' Hyperthyroidism according to Treatment Duration

Abstract

Backgruound: Changes in thyrotropin receptor antibody (TRAb) levels are associated with the clinical outcomes of Graves' hyperthyroidism. However, the effects of the patterns of TRAb changes on patient prognosis according to the treatment duration of antithyroid drugs (ATDs) are not well established.

Methods: In this retrospective cohort study, 1,235 patients with Graves' hyperthyroidism who were treated with ATDs for more than 12 months were included. Patients were divided into two groups according to treatment duration: group 1 (12-24 months) and group 2 (>24 months). Risk prediction models comprising age, sex, and either TRAb levels at ATD withdrawal (model A) or patterns of TRAb changes (model B) were compared.

Results: The median treatment duration in groups 1 (n=667, 54%) and 2 (n=568, 46%) was 17.3 and 37.1 months, respectively. The recurrence rate was significantly higher in group 2 (47.9%) than in group 1 (41.4%, P=0.025). Group 2 had significantly more goiter, thyroid eye disease, and fluctuating and smoldering type of TRAb pattern compared with group 1 (all P<0.001). The patterns of TRAb changes were an independent risk factor for recurrence after adjusting for other confounding factors in all patients, except in group 1. Integrated discrimination improvement and net reclassification improvement analyses showed that model B performed better than model A in all patients, except in group 1.

Conclusion: The dynamic risk model, including the patterns of TRAb changes, was more suitable for predicting prognosis in patients with Graves' hyperthyroidism who underwent longer ATD treatment duration.

Keywords: Antithyroid drug; Graves hyperthyroidism; Recurrence; Risk model; Thyrotropin receptor antibody.

Fig. 1.

A forest plot of the Cox proportional hazards model for recurrence-free survival in patients with Graves’ hyperthyroidism is shown. HR, hazard ratio; IQR, interquartile range; TED, thyroid eye disease; TRAb, thyrotropin receptor antibody; ATD, antithyroid drug; TSH, thyroid-stimulating hormone; AIC, Akaike information criterion. ^aP<0.05; ^bP<0.01.

Fig. 2.

A comparison of the models for the recurrence of Graves’ hyperthyroidism according to treatment duration is shown. (A) It shows the total number of patients using model A. (B) It shows the total number of patients using model B. (C) It shows group 1 patients using model A. (D) It shows group 1 patients using model B. (E) It shows group 2 patients using model A. (F) It shows group 2 patients using model B.