Increased risk of hypothyroidism and hyperthyroidism in patients with major depressive disorder: a population-based...

To determine the prevalence and incidence of hypothyroidism, hyperthyroidism, and risk factors in patients with major depressive disorder (MDD).

The National Health Research Institute provided a database of 1,000,000 random subjects for health service studies. We identified subjects aged ≥18 years who had at least 1 service claim during 2005 with a primary diagnosis of MDD or with a primary or secondary diagnosis of hypothyroidism or hyperthyroidism. We also compared the incidence of hypothyroidism and hyperthyroidism among patients with MDD and the general population from 2006 through 2010.

The prevalence of hypothyroidism in patients with MDD was higher than that in the general population (1.20% vs. 0.30%; odds ratio, 3.08; 95% confidence interval, 2.35-4.03) in 2005. The prevalence of hyperthyroidism was also higher in patients with MDD than in the general population (2.46% vs. 0.79%; odds ratio, 2.77; 95% confidence interval, 2.29-3.35) in 2005. The annual incidence of hypothyroidism was higher in patients with MDD than that in the general population (0.40% vs. 0.13%; risk ratio, 2.47; 95% confidence interval, 2.00-3.06). The annual incidence of hyperthyroidism was also higher in patients with MDD than that in the general population (0.72% vs. 0.32%; risk ratio, 2.06; 95% confidence interval, 1.75-2.43).

Patients with MDD had a higher prevalence and a higher incidence of hypothyroidism or hyperthyroidism than the general population. Female sex was a risk factor for hypothyroidism and hyperthyroidism in MDD.