Anticyclic Citrullinated Peptide Antibodies 3.1 and Anti-CCP-IgA Are Associated with Increasing Age in Individuals Without Rheumatoid Arthritis.

OBJECTIVE:We investigated the association of age and anticyclic citrullinated peptide antibodies (anti-CCP) in subjects without rheumatoid arthritis (RA). METHODS:Serum was tested for anti-CCP3.1 (IgG/IgA) in 678 first-degree relatives (FDR) of patients with RA and 330 patients with osteoarthritis (OA). Individual isotypes (anti-CCP-IgA and anti-CCP-IgG) were also tested in all FDR. RESULTS:In FDR, increasing age was significantly associated with positivity for anti-CCP3.1 (per year, OR 1.03) and anti-CCP-IgA (per year, OR 1.05) but not anti-CCP-IgG. In FDR and OA subjects, anti-CCP3.1 prevalence was significantly increased after age 50 years. CONCLUSION:Increasing age in individuals without RA should be considered in the interpretation of anti-CCP3.1 positivity.