Vitiligo and overt thyroid diseases: A nationwide population-based study in Korea

Background: Associations between vitiligo and thyroid diseases have been reported repeatedly. Objective: We investigated the associations between vitiligo and overt autoimmune thyroid diseases and thyroid cancer using the Korean National Health Insurance claims database. Methods: We defined patients with vitiligo as those whose records showed >= 4 physician contacts between 2009 and 2013 in which vitiligo was the principal diagnosis. We also established an age-and sex-matched control group without vitiligo (2 per 1 vitiligo patient). The outcomes of interest were concurrent Graves disease and Hashimoto thyroiditis (the patients were taking relevant thyroid medications) and thyroid cancer. Results: The study enrolled 73,336 vitiligo patients and 146,672 controls. Patients with vitiligo were at increased risks of Graves disease (odds ratio [OR] 2.610 [95% confidence interval {CI} 2.319-02.938]), Hashimoto thyroiditis (OR 1.609 [95% CI 1.437-1.802]), and thyroid cancer (OR 1.127 [ 95% CI 1.022-1.242]), compared with the controls. The associations were consistently stronger in males and younger patients. Limitations: Individual clinical information was not available, and the homogeneous population may limit the generalizability of the results. Conclusion: Vitiligo was significantly associated with overt autoimmune thyroid diseases and overt thyroid cancer.