In patients with clinically suspect arthralgia, the effects of anti-citrullinated protein antibodies (ACPA) on joint erosion are attributable to inflammation, according to results published in Arthritis Research & Therapy. These ACPA inflammatory effects are not independent of rheumatoid factor (RF).
The study included participants with clinically suspect arthralgia, defined as recent-onset (<1 year) arthralgia in small joints, without clinically-detectable synovitis on physical examination (n=507). Participants underwent measurement of serum ACPA and rheumatoid factor (RT). Participants also underwent 1.5 T contrast-enhanced magnetic resonance imaging (MRI) of the metacarpophalangeal, wrist, and metatarsophalangeal joints at baseline, with MRIs scored for local inflammation and erosions.
After evaluation, the researchers found that ACPA-positive participants had higher erosion scores compared with ACPA-negative participants (P =.006).
When the ACPA-positive participants were broken into subgroups, ACPA-positive participants with local inflammation still had higher erosion scores compared with ACPA-negative participants (P <.001).
However, ACPA-positive participants without subclinical inflammation did not have higher erosion scores compared with ACPA-negative participants (P =.68).
“The present data in patients with arthralgia showed that erosions are associated with the combined presence of ACPA and RF, rather than with ACPA alone, and preferentially occur in patients with joint inflammation,” the researchers wrote.
ten Brinck RM, Toes REM, van der Helm-van Mil AHM. Inflammation functions as a key mediator in the link between ACPA and erosion development: an association study in clinically suspect arthralgia [published online May 3, 2018]. Arthritis Res Ther. doi:10.1186/s13075-018-1574-3