Relevant factors in predicting the relapse of Graves disease after treatment with antithyroid drugs

Abstract

Objective To evaluate the prognostic factors of predicting the outcome of Graves disease (GD) after treatment with antithyroid drugs.Methods A retrospective audit was performed for 306 consecutive patients with newly diagnosed GD.They were divided into successful and failure groups (including recurrent and non-stop subgroups )according to the treatment outcomes.Different prognostic factors after treatment with antithyroid drugs were compared and the state of thyrotropin suppression was observed as the euthyroid state at Months 3,6 and 12 respectively.Results Among them,141patients (46.1％ ) were cured and 165 patients (53.9％) had treatment failures.Age at the time of diagnosis was (46 ±10) years in the successful group and (36 ±9) years in the failure group(t =3.152,P =0.002).Free T3 ( FT3 ) was (25.2 ±8.9) and ( 18.7 ±9.4) pmol/L in the failure and successful groups respectively (t =3.326,P =0.001).The FT3 to FT4 ratio and thyrotrophin receptor antibody (TRAb) levels were higher in the failure group ( t =3.331,3.389,P =0.001).Logistic regression analysis showed that thyroid size,FT3 to FT4 ratio and TRAb at the time of diagnosis were associated with failure outcomes.The ratio of continuing thyrotropin suppression in the recurrent subgroup was more than that in the successful group ( X2 =77.515,114.441,136.232,all P ＜ 0.01).Conclusions The GD patients with a large thyroid size and high pre-mediation levels of TRAb and FT3 to FT4 ratio are more prone to respond unfavorably to antithyroid drug treatment.And those with a large thyroid size and post-medication ophthalmopathy and continuing thyrotropin suppression have a high rate of recurrence. Key words: Graves disease; Recurrence; Antithyroid agents; Prognostic factors