[Clinical epidemiology of Basedow's disease in Belgium]

Graves' disease (GD) patients treated with antithyroid drugs (ATD) have overall relapse rates of 30-50% after ATD discontinuation. Conflicting data have been reported with regard to the usefulness of adding thyroxine (I-T4) during and after ATD treatment. Also, clinicians are still in search of useful factors to predict remission/recurrence after ATD withdrawal. Eighty two consecutive patients were treated with ATD for 15 months, combined with 12 months of I-T4. Then, patients were randomized (placebo-controlled double blind protocol) to continuing I-T4 versus a placebo for one year.

I-T4 administration during and after ATD treatment did not affect favorably the outcome, the final recurrence rate being 31%, in both placebo and I-T4 groups. Two factors were identified as independent and synergistic markers of a significantly increased risk of recurrence after ATD withdrawal: smoking and TSH receptor antibodies (TSHR-Ab) remaining positive at the end of ATD. Non smoking patients with a negative TSHR-Ab (end ATD) had a low (18%) recurrence risk, while smoking patients also with a negative TSHR-Ab had a higher (57%) recurrence risk. Non smoking patients with a positive TSHR-Ab (end ATD) had a 86% recurrence risk. Finally, smoking patients with a positive TSHR-Ab (end ATD) all recurred within 6 months.

1) T4 administration after ATD withdrawal does not improve recurrence rates; 2) two parameters, smoking and positive TSHR-Ab (at end ATD), were valid--albeit not absolute-predictors of the risk of recurrence in ATD-treated patients with Graves' disease.