Prognostic factors in the relapse of Graves disease

OBJECTIVE: To evaluate the variables which can be used as prognostic factors in predicting the outcome of Graves disease (GD) after treatment with antithyroid drugs. METHODS: We performed a retrospective audit of 204 patients with newly diagnosed Graves disease consecutively at the Ruijin Hospital. RESULTS: Overall, 110 patients (53.9%) were considered to be treatment failures. Age at the time of diagnosis was (31.0 +/- 12.2)years in the successful group and (36.3 +/- 14.0) years in the failure group. Free T3 (FT3) was (25.60 +/- 9.52) pmol/L and (19.16 +/- 6.38) pmol/L in the failure and the successful group (P = 0.001). FT3 to FT4 ratio and thyrotrophin receptor antibody (TRAb) levels were higher in the failure group (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 outcome. The patients reached euthyroid state at 3, 6, 9 and 12 months respectively and in the failure group the patients with continued thyrotropin suppression were more than those in the successful group (P = 0.001). CONCLUSIONS: Graves disease patients with large thyroid size, high levels of TRAb and FT3 to FT4 ratio before drug treatment are more likely to fail to respond to antithyroid drug treatment. We also found that patients with continuing thyrotropin suppression and attainment of euthyroid state in the course of treatment had low remission rate and prolonged therapy.