Positive impact of long-term antithyroid drug treatment on the outcome of children with Graves' disease: national long-term cohort study.

ABSTRACT

CONTEXT Drug-based therapy is usually the initial treatment for Graves' disease (GD) hyperthyroidism in children, but there is some debate about treatment duration. OBJECTIVE: Our objective was to assess the effect of long-term carbimazole therapy on GD remission in children and its determinants. DESIGN AND SETTING: This was an observational prospective multicenter follow-up cohort study. PARTICIPANTS: Participants included 154 children newly diagnosed with GD between 1997 and 2002. The intention was to treat patients with three consecutive courses of carbimazole, each lasting 2 yr. Definitive treatment was performed in cases of poor compliance with antithyroid drug (ATD) treatment, thyrotoxicosis relapse, or major adverse effects of ATD treatment. MAIN OUTCOME MEASURE: The main outcome measure was remission for at least 18 months after the completion of each course of ATD treatment. RESULTS: The median duration of follow-up was 10.4 (9.0-12.1) yr. Overall estimated remission rates (95% confidence interval) 18 months after the withdrawal of ATD treatment increased with time and were 20 (13-26), 37 (29-45), 45 (35-54), and 49 (40-57)% after 4, 6, 8, and 10 yr follow-up, respectively. A multivariate competing risk model revealed an independent positive effect of less severe forms of hyperthyroidism at diagnosis [subhazard ratio of 1 for patients with free T(4) <35 pmol/liter vs. 0.4 (0.20-0.80) for free T(4) ≥ 35 pmol/liter; P = 0.01] and of the presence of other autoimmune conditions [subhazard ratio of 2.23 (1.19-4.18); P = 0.01] on remission rate after medical treatment. CONCLUSION: About half the patients achieved remission after carbimazole discontinuation, and there seems to be a plateau in the incidence of remission achieved after 8-10 yr ATD therapy.