Simon TA, et al. - The goal of this study was to examine the prevalence of co-existing autoimmune disease in the case of rheumatoid arthritis (RA). It was illustrated that the patients with RA displayed more concurrent autoimmune diseases than patients with OA. Hence, the interrelationship between RA and other autoimmune diseases, and outcomes linked with the occurrence of multiple autoimmune diseases could exhibit a significant role in the disease comprehension, management, and treatment decisions.

Methods

• The design of this research was a cross-sectional study.
• It was conducted using a US administrative health-care claims database to screen for the prevalence of multiple autoimmune diseases in patients with RA and osteoarthritis (OA).
• Herein, each patient diagnosed with RA between January 1, 2006 and September 30, 2014 was age- and sex-matched with five patients having OA.
• A comparison was pursued of the prevalence of 37 pre-specified autoimmune diseases during the 24-month period before and after RA or OA diagnosis.

Results

• The authors analyzed 286,601 patients with RA and 992,838 matched patients (from 1,421,624 records) with OA.
• At least one and more than one autoimmune diseases were detected in 24.3% and 6.0% of patients with RA compared with 10.5% and 1.4% of patients with OA, respectively, during the baseline period.
• Highest prevalence rates for patients with RA appeared to be for systemic lupus erythematosus (3.8% versus 0.7% for OA) and psoriatic arthritis (3.2% versus 0.4%).
• The prevalence of ankylosing spondylitis (OR 8.0; 95% CI 7.6, 8.5) and psoriatic arthritis (OR 7.8; 95% CI 7.6, 8.1) displayed highest odds ratios (ORs) comparing RA with OA.