Body mass index and risk of autoimmune diseases: a study within the Danish National Birth Cohort

Int J Epidemiol. 2014 Jun;43(3):843-55. doi: 10.1093/ije/dyu045. Epub 2014 Mar 7.


Background: A possible aetiological link between obesity and certain autoimmune diseases (ADs) has been suggested. We investigated the associations between body mass index (BMI, kg/m2) and 43 ADs.

Methods: 75,008 women participating in the Danish National Birth Cohort were followed during a median time of 11 years. Diagnoses on ADs were retrieved from the Danish National Patient Register. Cox proportional hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated adjusting for potential confounders (smoking, alcohol, parity and socio-occupational status).

Results: During follow-up, 2430 women (3.2%) developed a total of 2607 new-onset ADs. Risk of any autoimmune disease was increased in obese women (HR, 1.27; 95% CI, 1.11 to 1.46) compared with normal weight women (18.5-≤25 kg/m2). Obese women (BMI≥30 kg/m2) were at increased risk of sarcoidosis (HR 3.59; 95% CI, 2.31 to 5.57) and type 1 diabetes mellitus (HR 2.67; 95% CI, 1.71 to 4.17). Risk of dermatitis herpetiformis increased by 14% (95% CI, 1% to 30%) per BMI unit. Conversely, risk of celiac disease and Raynaud's phenomenon decreased by 7% (95% CI, 1% to 13%) and 12% (95% CI, 4% to 19%) per BMI unit, respectively. Further associations between BMI and risk of psoriasis, rheumatoid arthritis and Crohn's disease were suggested.

Conclusions: BMI was found to be associated with several Ads. This was most pronounced between obesity and risk of sarcoidosis and and risk of type 1 diabetes mellitus. These novel findings need confirmation and the possible role of adipose tissue-derived immunological changes in the development of autoimmune reactions needs consideration.

Keywords: Body mass index; autoimmune disease; inflammation; leptin; obesity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Autoimmune Diseases / epidemiology*
  • Body Mass Index*
  • Cohort Studies
  • Denmark / epidemiology
  • Female
  • Health Behavior
  • Humans
  • Incidence
  • Longitudinal Studies
  • Obesity / epidemiology*
  • Risk Factors
  • Socioeconomic Factors