Morbidity before and after the diagnosis of hyperthyroidism: a nationwide register-based study

PLoS One. 2013 Jun 20;8(6):e66711. doi: 10.1371/journal.pone.0066711. Print 2013.


Background: Hyperthyroidism has been linked with different morbidities, like atrial fibrillation, stroke and diabetes mellitus. However, our knowledge regarding the extent and temporal relation between hyperthyroidism and other diseases is fragmented. Here, we aimed at evaluating various morbidities before and after the diagnosis of hyperthyroidism.

Methods: Observational cohort study. From nationwide Danish health registers 2631 hyperthyroid singletons and 375 twin pairs discordant for hyperthyroidism were identified and followed for an average of 6 years (range 0-13). Data on the occurrence of cardiovascular diseases, lung diseases, diabetes mellitus, rheumatic diseases and malignant diseases was obtained by person-to-person record linkage with the National Danish Patient Register and/or the Danish National Prescription Registry (lung diseases and diabetes mellitus). Logistic and Cox regression models were used to assess the risk of morbidity before and after the diagnosis of hyperthyroidism, respectively. All Cox regression analyses were adjusted for the degree of co-morbidity preceding the diagnosis of hyperthyroidism, using the Charlson score.

Results: Hyperthyroid individuals had a significantly higher risk of being diagnosed with cardiovascular diseases (odds ratio (OR) 1.65; 95% confidence interval (CI): 1.45-1.87), lung diseases (OR 1.53; 95% CI: 1.29-1.60), and diabetes mellitus (OR 1.43, 95% CI: 1.20-1.72), but not with malignant diseases (OR 1.16, 95% CI: 0.99-1.36) prior to the diagnosis of hyperthyroidism. After the diagnosis of hyperthyroidism, subjects had a significantly higher risk of being diagnosed with cardiovascular diseases (hazard ratio (HR) 1.34; 95% CI: 1.15-1.56), lung diseases (HR 1.28; 95% CI: 1.10-1.49), and diabetes mellitus (HR 1.46; 95% CI: 1.16-1.84), but not with rheumatic diseases (HR 1.39, 95% CI: 0.92-2.09) or malignant diseases (HR 1.18, 95% CI 0.97-1.42).

Conclusions: We demonstrate a significantly increased burden of morbidity, both before and after the diagnosis of hyperthyroidism.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Cardiovascular Diseases / diagnosis
  • Cardiovascular Diseases / epidemiology
  • Cohort Studies
  • Denmark / epidemiology
  • Diabetes Mellitus / diagnosis
  • Diabetes Mellitus / epidemiology
  • Female
  • Humans
  • Hyperthyroidism / diagnosis*
  • Hyperthyroidism / epidemiology*
  • Logistic Models
  • Lung Diseases / diagnosis
  • Lung Diseases / epidemiology
  • Male
  • Middle Aged
  • Morbidity
  • Proportional Hazards Models
  • Registries / statistics & numerical data*
  • Time Factors

Grants and funding

D.A., K.C., A.G. and T.H.B. have nothing to declare. F.B. and M.T. are enrolled as P.h.D. students financed by the School of Endocrinology, University of Southern Denmark in Odense. F.B. has also received funding from the Danish Thyroid Patient Organization. L.H. is the recipient of an unrestricted research grant from the Novo Nordisk Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.