Objective: To investigate the long-term prognosis of patients with Graves' disease (GD) after antithyroid drug (ATD) treatment and follow-up outside of highly specialised care.
Design and methods: Medical records of all patients diagnosed with first-time GD in 2000-2010 with at least 6 months ATD treatment at a central hospital and follow-up in primary health care in the county of Norrbotten in northern Sweden were retrospectively reviewed. Patients were followed for relapse until 31st December 2012. We included 219 patients (mean age 46 years, 82.5% women) with follow-up of maximum 10 years and 829 observed patient years. Data were analysed using Kaplan-Meier estimates and log-rank test.
Results: During the observation period, 43.5% of the patients had relapsed into active GD. The cumulative relapse rates were 22.6, 30.2, 36.9 and 41.5% after 6 months, 1, 3 and 5 years respectively. The presence of goitre (P=0.014) predicted relapse. Previous smoking was protective against relapse (P=0.003). The levels of free thyroxine or free tri-iodothyronine, age, gender, current smoking and ophthalmopathy did not predict relapse. Agranulocytosis was found in 1.7% (95% CI 0.7-4.0%).
Conclusion: A long-term remission of 56.5%, in an iodine-sufficient area where ATD is offered to most patients in the real world of central and district hospitals, is higher than in most studies. Relapse was most common during the first year, and prognosis was excellent after 4 years without relapse. The protective effect of previous smoking merits further research.