Pain and inflammation are often discordant among patients with rheumatoid arthritis (RA). In a mouse model, systemic injection of polyclonal autoantibodies against citrullinated proteins (ACPA) induced pain-like behaviours.1 A recent study also suggested that specific monoclonal ACPAs may be responsible for tenosynovitis and pain behaviours in mice.2 Given these findings, our goal was to examine the association between a subset of ACPA, anti-cyclic citrullinated peptides (anti-CCP) and pain in humans with RA.

Patients with active RA were enrolled in the Central Pain in RA study. Anti-CCP positivity was categorised as positive/negative and into quantiles . Experimental measures of peripheral sensitivity were pressure pain thresholds (PPTs) at the wrists and knees. Measures of central sensitivity were PPT at the trapezius muscles, PPT at the thumbnails, temporal summation (TS) and conditioned pain modulation (CPM). Patient-reported measures included pain intensity on a Numeric Rating Scale and pain interference assessed by the Patient-Reported Outcomes Measurement Information System (PROMIS) computerised adaptive test. Associations between anti-CCP positivity and pain were examined using multiple linear regression and linear trend tests. Exploratory subgroup analyses were performed, stratified by sex, high sensitivity C-reactive protein (hsCRP) (≤ or >3 mg/L) and swollen joint count (SJC ≤or >1) (see online supplemental materials).

[ard-2023-224492supp001.pdf]

Among the 255 participants, 159 (62.4%) were positive for anti-CCP antibody. Mean (SD) DAS-28 score was 4.4 (1.2) (online supplemental table 1). Comparing …