Ageing linked to seronegativity in RA

Ageing is independently associated with seronegative rheumatoid arthritis (RA) in patients who are female, have a nonsmoking history, and a body mass index (BMI) <25 kg/m², according to a study.

The investigators examined the factors affecting rheumatoid factor (RF) and anticyclic citrullinated peptide antibody (anti-CCP) positivity in patients with RA. They included all consecutive RA patients treated at Keio University Hospital in Tokyo, Japan, between 2016 and 2017.

Age at diagnosis, sex, smoking habit, BMI, and family history were recorded, while the relationship between these variables and RF and anti-CCP positivity were analysed.

In total, 1,685 patients with RA were included in the analysis. Their mean age at diagnosis was 51.9 years. Majority (83.4 percent) of the patients were women.

Increases in age at RA diagnosis (grouped by decade) were associated with an almost linear reduction in positivity rates of RF (80.5 percent, 84.2 percent, 81.1 percent, 78 percent, 74.6 percent, 62.6 percent, 51.4 percent; p<0.001) and anti-CCP (79.9 percent, 87.4 percent, 81.7 percent, 74 percent, 70.5 percent, 60.2 percent, 37.1 percent; p<0.001) after ≥30 years of age.

In multivariate analysis, age showed an independent association with seronegativity in women (RF: odds ratio [OR], 0.98, 95 percent confidence interval [CI], 0.97‒0.99; p<0.001; anti-CCP: OR, 0.97, 95 percent CI, 0.96‒0.98; p<0.001), nonsmoking history (RF: OR, 0.98, 95 percent CI, 0.97‒0.99; p<0.001; anti-CCP: OR, 0.97, 95 percent CI, 0.96‒0.98; p<0.001), and BMI <25 kg/m² (RF: OR, 0.98, 95 percent CI, 0.97‒0.99; p<0.001; anti-CCP: OR, 0.97, 95 percent CI, 0.97‒0.98; p<0.001).