Antithyroid drugs and Graves' disease - prospective randomized assessment of long-term treatment

OBJECTIVE Although antithyroid drugs (ATD) are widely used in the treatment of Graves' disease, management protocols, especially treatment duration, r emain a subject of debate. The rate of relapse after short-term regimens of less than 6 months with ATD at decreasing doses is higher than after longe r treatments from 12 to 24 months. As no prospective study has provided dat a on even longer protocols exceeding 2 years, we conducted a prospective tr ial to determine potential benefits of a 42-month treatment compared with a n 18-month treatment, DESIGN, PATIENTS AND MEASUREMENTS The aim of this prospective randomized trial was to compare relapse rates achieved two years after treatment withdrawal in p atients who received carbimazole at decreasing doses for 18 months (n = 62) vs 42 months (n = 72). In addition to clinical relapse rate, the percentag e of patients who normalized antithyroperoxidase (TPO) antibody and anti-TS H receptor stimulating antibody (TSAb) levels and early iodine uptake at th e end of treatment were assessed as outcome criteria. RESULTS The relapse rate two years after discontinuation of treatment did n ot differ significantly in patients treated for 18 months from those treate d for 42 months (36% vs 29%, NS), At the end of treatment, there was no sig nificant difference between the two groups in the percentage of anti-TPO po sitive patients (53% vs 46%, NS) or early iodine uptake (27% vs 21%, NS). A lthough the percentage of patients with TSAb was significantly lower in the 42-month treatment group (18% vs 42%, P = 0.004) at treatment withdrawal, the percentage of TSAb-positive patients did not significantly decrease bet ween 18 and 42 months in this group (27% vs 18%, NS), CONCLUSION Treatment duration greater than 18 months did not improve remiss ion rate determined 2 years after treatment withdrawal or immunological var iables or early iodine uptake measured at the time of discontinuation of tr eatment, These findings would indicate that, when a defined duration treatm ent is planned, prolonging treatment beyond 18-months does not provide any additional benefit.