In a study presented at the American College of Rheumatology Convergence, researchers found a clear association between obesity and increased risk for several autoimmune diseases, and stressed the importance of recognizing obesity as a potential contributor to immune dysregulation.

The investigators aimed to assess the prevalence of obesity among patients with autoimmune conditions and evaluate the risk of autoimmune diseases in obese individuals using data from the National Inpatient Sample (NIS) database. 

This retrospective study analyzed data from adults (≥18 years) hospitalized between 2016 and 2019, focusing on patients with obesity (body mass index ≥30) and autoimmune diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriatic arthritis (PsA), and dermatomyositis. Patient identification relied on ICD-10 diagnostic codes. The study calculated the prevalence of obesity in individuals with specific autoimmune conditions. Logistic multivariate regression analysis was used to estimate adjusted odds ratios (AORs), controlling for confounding variables such as age, race, sex, and comorbidities, to establish the association between obesity and autoimmune diseases. 

According to the results, the analysis identified over 13 million patients with obesity in the dataset. The prevalence of obesity among patients with autoimmune diseases varied by condition; 14.66% had RA; 14.73% had been diagnosed with SLE; and 19.93% had psoriatic arthritis.

Obesity was associated with significantly increased odds of developing  PsA (AOR 1.92, 95% CI: 1.65–2.23, p < 0.001); RA (AOR 1.29, 95% CI: 1.28–1.30, p < 0.001); SLE (AOR 1.17, 95% CI: 1.15–1.18, p < 0.001); and dermatomyositis (AOR 1.12, 95% CI: 1.03–1.21, p= 0.011) .

Conversely, obese individuals were less likely to have systemic sclerosis (AOR 0.54, 95% CI: 0.51–0.56, p< 0.001). These associations remained statistically significant after adjusting for demographic and clinical variables, underscoring the robust link between obesity and certain autoimmune conditions. 

This large-scale study highlights a clear association between obesity and increased risk for several autoimmune diseases, particularly psoriatic arthritis, RA, and SLE. However, the lower odds of systemic sclerosis in obese individuals warrant further investigation. Further research should explore these pathways to inform preventive strategies and therapeutic approaches tailored to obese patients at risk for autoimmune diseases. 

Reference
Rabah S. Obesity and risk of autoimmune diseases: insights from the national inpatient sample. Presented at: American College of Rheumatology Convergence. November 14-19, 2024; Washington, DC.