Using the presence of anticarbamylated protein (anti-CarP) antibodies has no additional predictive value for the progression of rheumatoid arthritis (RA) among patients with undifferentiated arthritis (UA) when the disease is defined according to 2010 criteria, according to results published in Arthritis Research & Therapy.
These results may be inherent to the composition of the 2010 criteria and therefore may apply to other novel autoantibodies.
The study included participants with UA according to the 1987 criteria (n=1352). When the 2010 criteria were used, 838 of these participants were classified as having UA. The researchers evaluated whether participants fulfilled with 1987 or 2010 criteria after 1 year. They used logistic regression analyses with RA as the outcome and anticitrullinated protein antibodies (ACPA), rheumatoid factor (RF), and anti-CarP antibodies as predictors.
During the first year of follow-up, 33% of the 1987 UA participants and 6% of the 2010 UA participants had progression to RA.
Among the 1987 UA participants, anti-CarP antibodies were associated with progression to RA, and this association remained significant when a correction was made for the presence of ACPA and RF (odds ratio [OR], 1.7; 95% CI, 1.2-2.4).
Among the 2010 UA participants, anti-CarP antibodies were associated with progression to RA; however, not when a correction was made for the presence of ACPA and RF (OR, 0.8; 95% CI, 0.3-2.1).
“More research is needed to identify [those with] early RA among (2010 criteria-negative) UA patients, but based on the composition of the current classification criteria, it will be interesting to evaluate other, non-autoantibody biomarkers,” the researchers wrote.
Boeters DM, Trouw LA, van der Helm-van Mil AHM, van Steenbergen HW. Does information on novel identified autoantibodies contribute to predicting the progression from undifferentiated arthritis to rheumatoid arthritis: a study on anti-CarP antibodies as an example. Arthritis Res Ther. 2018;20:94.