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.