Hypothyroidism is a predictor of disability pension and loss of labor market income: a Danish register-based study

Abstract

Background: Hypothyroidism is associated with an increased somatic and psychiatric disease burden. Whether there are any socioeconomic consequences of hypothyroidism, such as early retirement or loss of income, remains unclarified.

Aim: Our aim was to examine, compared with a matched control group, the risk of receiving disability pension (before the age of 60) and the effect on labor market income in patients diagnosed with hypothyroidism.

Methods: This was an observational register-based cohort study. By record linkage between different Danish health registers, 1745 hypothyroid singletons diagnosed before the age of 60 were each matched with 4 non-hypothyroid controls and followed for a mean of 5 (range 1-31) years. Additionally, we included 277 same-sex twin pairs discordant for hypothyroidism. The risk of disability pension was evaluated by the Cox regression analysis. Changes in labor market income progression over 5 years were evaluated using a difference in difference model.

Results: With a hazard ratio of 2.24 (95% confidence interval = 1.73-2.89), individuals diagnosed with hypothyroidism had a significantly increased risk of disability pension. This remained significant when adjusting for educational level and comorbidity (hazard ratio = 1.89; 95% confidence interval = 1.42-2.51). In an analysis of labor market income, 2 years before compared with 2 years after the diagnosis of hypothyroidism, the hypothyroid individuals had on average a €1605 poorer increase than their euthyroid controls (P < .001). Essentially similar results were found in the twin population.

Conclusion: A diagnosis of hypothyroidism before the age of 60 is associated with loss of labor market income and an 89% increased risk of receiving a disability pension.