[Long-term follow up after antithyroid drug treatment in Graves' disease]

In Europe antithyroid drug (ATD) therapy is the preferred initial treatment for patients with a first episode of Graves' disease. Results of long-term recurrence rates following ATD therapy are conflicting. The main goal was to assess long-term recurrence rate after ATD treatment. Secondarily we tried to verify chemical and clinical findings (thyrotropin receptor antibodies (TRAb), duration of primary treatment, age and goitre size) as predictive factors.

Records of 94 patients with a first episode of Graves' disease (1990-1995) treated by ATD were retrospectively analyzed. 18 patients were lost for follow up investigations, the remaining 76 (65 women, 11 men, age 16-76 years) patients were followed for 99 (+/- 22) months (mean +/- SD). To verify the predictive factors a logistic regression analysis was done.

Among the 76 patients 16 underwent near-total resection (n = 5) or radioiodine therapy (n = 11) after initial ATD treatment. Sixty patients were treated during 19 +/- 16 months (mean +/- SD) with ATDs and were euthyroid when treatment was stopped. Thirteen of the 60 patients (21.7%) remained in remission after discontinuation of ATD therapy, in 42 patients (70%) hyperthyroidism recurred, in four patients (6.7%) ATD could not be stopped, one patient (1.7%) had a persistent hypothyroidism after discontinuation of ATD. Relapse rate was inversely correlated with duration of primary ATD treatment (p < 0.05), but not with TRAb titer at the time of diagnosis nor at the time of ATD discontinuation. Also, no correlation could be noticed with goitre size at the time of diagnosis. An inverse correlation of the age at the time of diagnosis with relapse rate was of only borderline significance (p = 0.055).

Initial successful treatment with ATD is followed by a high recurrence rate in our population. Two possible negative predictors of relapse are short duration of primary ATD treatment and young age at the time of diagnosis. TRAb titer at the time of diagnosis or at the time of ATD discontinuation and goitre size seem to have no influence on the outcome.