Predictors of outcome and comparison of different drug regimens for the prevention of relapse in patients with Graves' disease

Objective: To investigate the effect of different antithyroid drug (ATD) regimens on relapse rates of Graves' disease, and to look for predictors of relapse. Design and Methods: In a prospective two-way factorial randomized clinical trial, 218 patients with Graves' disease Were assigned to ATD combined with L-thyroxine (L-T-4) or ATD alone for 12 months. After discontinuation of antithyroid therapy, each group was stratified to either 12 months further treatment with L-T-4 or no treatment. Clinical and biochemical assessments were carried out before treatment, after 3 and 6 weeks, and every third month for 12 months. If the patients lacked symptoms of relapse, laboratory tests were performed every third month for the second year, and thereafter annually. Results: The proportion of all patients with relapse was 47.7% 2 years after withdrawal of ATD. There was no difference in relapse rates between the treatment groups (P = 0.217, log-rank test). Smokers had a higher relapse rate than non-smokers (58.4% vs 38.8%, P = 0.009). Patients who were thyrotropin-receptor antibody (TRAb) positive after 12 months of antithyroid therapy had a higher relapse rate than those who were negative (72.5% vs 36.8%, P < 0.0001). Similarly, relapse was more frequent (55.5%) in patients. having large goiter compared with subjects with small goiter (36.3%, P = 0.0007). Conclusions: Relapse rates of Graves' disease were independent of ATD regimen whether,followed by L-T4 therapy or not. Smoking, large goiter and presence of TRAb at the end of ATD therapy were strong predictors of relapse.