Risk of non-thyroidal autoimmune diseases in patients with Graves' disease: a nationwide retrospective cohort study.

Objective: Graves' disease (GD) is a major autoimmune thyroid disorder and associated with non-thyroidal autoimmune disease (NTAD). We aimed to investigate the risk of NTAD in patients with GD compared with age- and sex-matched controls and to evaluate whether the risk differs between individuals with or without Graves' ophthalmopathy (GO).

Methods: This was a retrospective cohort study using data from the Korean National Health Claims database. We included 77 401 patients with GD (2,310 with GO) and 77 401 age- and sex-matched controls. Risk of NTAD were compared between the entire cohort and within the GD cohort.

Results: During a mean follow-up period of 9 years, NTAD developed in 12 341 (16.1%) patients in the GD cohort. Risk for systemic lupus erythematosus (SLE) [adjusted hazard ratio (aHR):1.15, 95% confidence interval (CI): 1.02-1.29], vitiligo (aHR: 1.24, 95% CI: 1.10-1.40), and alopecia areata (aHR: 1.11, 95% CI: 1.10-1.40) were higher in the GD cohort than in the control cohort. In the GD cohort, risk for SLE (aHR: 1.60, 95% CI: 1.11-2.33), Sjogren's syndrome (aHR: 1.89, 95% CI: 1.30-2.74), and ankylosing spondylitis (aHR: 1.53, 95% CI: 1.08-2.17) were higher in the GO group than in the non-GO group.

Conclusion: This study demonstrated an increased risk of SLE, vitiligo and alopecia areata in patient with GD. In the GD cohort, patients with GO had an increased risk of SLE, Sjogren's syndrome and ankylosing spondylitis. These findings suggest that importance of implementing a strategy for early detection of NTAD based on the presence of GO.