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The following is a summary of “Polyautoimmunity in Patients With Anticyclic Citrullinated Peptide Antibody–Positive and –Negative Rheumatoid Arthritis: A Nationwide Cohort Study From Denmark,” published in the February 2024 issue of Rheumatology by Kristensen et al.
Researchers conducted a retrospective study to assess and contrast the rates of polyautoimmunity occurrence and development in rheumatoid arthritis (RA) patients based on their anti-cyclic citrullinated peptide antibody (anti-CCP) status.
They conducted a nationwide register-based cohort study, identifying RA patients from the DANBIO rheumatology register with a disease duration of two years or less and who had undergone anti-CCP testing in the Register of Laboratory Results for Research. The polyautoimmunity outcome comprised 21 non-rheumatic autoimmune conditions identified through the linkage between the Danish Patient Registry and Prescription Registry. Modified Poisson regression was utilized to calculate age- and sex-adjusted prevalence ratios (PR) to compare prevalence at diagnosis between anti-CCP–positive and anti-CCP–negative patients. Additionally, cause-specific Cox regression models were employed to estimate HR for polyautoimmunity within five years of entry into DANBIO.
The results showed that among the 5,839 anti-CCP–positive and 3,799 anti-CCP–negative patients with RA, the prevalence of prespecified polyautoimmune diseases in the Danish registers at the first visit was 11.1% and 11.9% (PR 0.93, 95% CI 0.84-1.05). The most common autoimmune diseases observed were autoimmune thyroid disease, inflammatory bowel disease, and type 1 diabetes mellitus. Over a mean follow-up period of 3.5 years, only a small number of patients (n = 210) developed polyautoimmunity (HR 0.6, 95% CI 0.46-0.79).
Investigators concluded that around 10% of patients with RA have another autoimmune disease at diagnosis, with this risk more stable for those without anti-CCP antibodies.
Source: jrheum.org/content/early/2024/02/23/jrheum.2023-0907
