Link Between Autoantibody Levels and Disease Activity in Rheumatoid Arthritis Dependent on Baseline Inflammation

Among patients with high vs low rheumatoid arthritis (RA) inflammatory activity, there is an association between changes in autoantibody levels and disease activity, according to study results published in Clinical and Experimental Rheumatology.

While there are mixed evidence on the use of autoantibody levels for monitoring disease activity in RA, their prognostic value is widely accepted; levels of anticyclic citrullinated peptide (CCP) antibodies and rheumatoid factor (RF) at baseline can predict the prognosis of patients with RA. The objective of the current study was to identify predictors for changes in autoantibody levels and disease activity over time.

The study included 78 patients with seropositive RA (mean age, 62.31 years; 55.1% women) and evidence for anti-CCP, antimutated citrullinated vimentin (MCV), and/or RF autoantibodies.

Overall anti-CCP levels did not change over time (P =.833), but the reduction of anti-CCP levels over time was greater among patients with longer disease duration at baseline (-4.4 U/mL/y disease duration, P =.048) and no initial erosions (-2.0 U/mL/mo, P =.0017). On the other hand, the presence of erosions at baseline predicted an increase in anti-CCP levels (+1.6 U/mL/mo, P =.008). Levels of anti-MCV and RF did not change over time and disease duration or the presence of erosions had no statistically significant effect on the autoantibodies levels. Rituximab treatment predicted a decrease in anti-MCV, anti-CCP, and RF levels over time.

Since rituximab had the strongest influence on autoantibody levels, an analysis to determine patients’ traits associated with a better correlation of changes in autoantibodies with disease activity score 28 joints (DAS28) excluded rituximab users. The association between changes of autoantibody levels andDAS28 was more significant in patients with high disease activity. Fluctuation of autoantibody levels associated more with disease activity in patients with higher grades of morning stiffness (P =.002) and among those who received with disease-modifying antirheumatic drugs (P =.02). Furthermore, high erythrocyte sedimentation rate (ESR) and visual analog scale (VAS), as well as more swollen and tender joints at baseline, were also identified as significant predictors of disease activity in patients not receiving rituximab.

Study limitations included the retrospective design, single center study, the heterogeneity of the study population, and missing data on smoking habits.

“[S]tudies investigating changes of autoantibody levels in RA should always consider markers of inflammatory activity, like tender and swollen joints, ESR, pain VAS and morning stiffness as confounders when interpreting results,” the researchers concluded.

Disclosure: One of the study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of disclosures.

Reference

Pongratz G, Frieser R, Brinks R, et al. Association between autoantibody level and disease activity in rheumatoid arthritis is dependent on baseline inflammation. Clin Exp Rheumatol. 2020;38(4):691-698.