Truchetet ME, et al. – The clinicians examined the prevalence of anti–carbamylated protein (CarP) antibodies in patients with early arthritis and investigated their association with clinical features, final diagnosis, prognosis, and comorbidities. They detected anti–CarP antibodies in one–third of patients with early arthritis and among one fourth of the rheumatoid factor (RF)–negative and anti–citrullinated peptides antibodies (ACPA)–negative patients. Moreover, anti–CarP antibodies were particularly associated with a more severe radiographic fate. Thus, these antibodies were probably useful in identifying patients at–risk of erosive evolution in an early arthritis population.

Methods

• With the aid of ELISA, the presence of anti–CarP antibodies among patients with early arthritis belonging to the ESPOIR French cohort (n=720) was evaluated.
• The prevalence of anti–CarP antibodies was determined in different patient subgroups that were stratified according to their anti–citrullinated peptides antibodies (ACPA) and/or rheumatoid factor (RF) status.
• In this population, diagnosis and prognosis values of the test were evaluated.

Results

• The presence of anti–CarP was reported in approximately one third of the patients (32.6%) and 23.6% of the RF and/or ACPA sero–negative patients.
• Anti–CarP positivity was associated with a more active disease status at baseline and over time with a significantly higher DAS28–ESR level at M36 (3.1±0.11 vs. 2.8±0.06, p=0.03).
• Anti–CarP–positive early arthritis was associated with a higher risk of developing erosions after 96 months of follow–up (55.6% among the anti–CarP+ patients vs. 37.3% among the anti–CarP– patients, OR=2.1 [1.2–3.6], p=0.009).
• This association was particularly true when anti–CarP was associated with ACPA positivity.
• In addition, ACPA positivity alone–early arthritis was not associated with a higher risk of erosive evolution.