In individuals without rheumatoid arthritis (RA), increasing age is associated with anti-CCP3.1 positivity, according to study results published in the Journal of Rheumatology.
The study included participants without RA, including first-degree relatives (FDRs) of patients with RA (n=678) and participants with osteoarthritis (OA; n=330). The researchers tested serum for anti-CCP3.1. They also tested individual isotypes (anti-CCP-IgA and anti-CCP-IgG) in all FDRs.
Of 678 FDRs, 9.1% (n=62) were anti-CCP3.1 positive, 8.6% (n=58) anti-CCP-IgA positive, and 4.9% (n=33) anti-CCP-IgG positive. Of 330 participants with OA, 28 were anti-CCP3.1 positive.
The results indicated that in FDRs, increasing age was significantly associated with anti-CCP3.1 positivity (odds ratio [OR], 1.03 per year) and anti-CCP-IgA positivity (OR, 1.05 per year). However, there was no association between age and anti-CCP-IgG positivity.
In all participants (FDRs and patients with OA), anti-CCP3.1 prevalence increased significantly after age 50. After stratifying by sex, the researchers found that anti-CCP3.1 positivity was associated with age in both men (OR, 1.07) and women (OR, 1.03).
In FDRs, anti-CCP-IgA positivity was also associated with increasing age (OR, 1.04). After stratifying by sex, the researchers found that anti-CCP-IgA positivity was associated with age in both men (OR, 1.09) and women (OR, 1.04).
The researchers found that FDRs aged ≥50 were more likely to be anti-CCP3.1 positive compared with participants with OA aged ≥50 (41/271 [15.1%] vs 25/275 [9.1%], respectively; P=.03).
“Future studies are also needed to evaluate associations of age and secretory IgA [antibodies to citrullinated protein/peptide antigens] ACPA, to determine specific epitopes targeted by ACPA in older individuals and to establish the performance of anti-CCP3.1 positivity to predict future classified RA in older individuals,” the researchers wrote.
Berens HM, Polinski KJ, Mikuls TR, et al. Anti-CCP3.1 and anti-CCP-IgA are associated with increasing age in individuals without rheumatoid arthritis. [published online April 15, 2019]. J Rheumatol. doi:10.3899/jrheum.180897