Anti-CCP3.1 and Anti-CCP-IgA Are Associated with Increasing Age in Individuals Without Rheumatoid Arthritis

Objective We investigated the association of age and anti-cyclic citrullinated peptide (CCP) antibodies in subjects without RA. Methods Serum was tested for anti-CCP3.1 (IgG/IgA) in 678 first-degree relatives (FDRs) of RA patients and 330 osteoarthritis (OA) subjects. Individual isotypes (anti-CCPIgA and anti-CCP-IgG) were also tested in all FDRs. Results In FDRs, 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-CCPIgG. In FDRs and OA subjects, anti-CCP3.1 prevalence was significantly increased after age 50. Conclusion Increasing age in individuals without RA should be considered in the interpretation of anti-CCP3.1 positivity.