Summary

 Background: The presence of anti-citrullinated peptide/protein antibody (ACPA) has a high specificity and predictive value for the development of rheumatoid arthritis (RA). Some studies have shown decreased titers of this antibody after treatment with infliximab.

Objectives: To assess the changes in ACPA titers in patients with RA after treatment with infliximab as a first biological agent, and to correlate these variations with non-infusion-related adverse effects.

Methods: In a prospective multicenter observational study involving 48 research centers, we assessed 139 patients with established moderate-to-severe RA diagnosed according to American College of Rheumatology criteria. Samples were collected before and 6–12 months after treatment.

Results: The mean age of the study patients was 50.6 years old, and 118 were female (84.9%). Statistically significant variations in ACPA titers were noted in 47 patients (before and after treatment) (P = 0.012). Overall, ACPA titers were decreased in 32 (65.3%) and increased in 15 (34.7%). No correlation was found between severe or mild adverse effects in patients presenting variations in ACPA titers.

Conclusions: The present study showed that infliximab affected ACPA titers, promoting mainly a decrease; however, this was not related to the occurrence of non-infusion-related adverse effects.