Background It remains still unclear whether autoantibodies are useful biomarkers to tailor the choice of biological treatment in rheumatoid arthritis (RA).

Objectives The main aim of our study was to identify predictive factors for response to TNF inhibitors in patients with established RA with a special focus on baseline levels of autoantibodies.

Methods We performed a prospective observational 12 months study in 90 consecutive active established RA receiving their first anti-TNF agent: adalimumab (33), etanercept (30), infliximab (27). Standard assessments consisted of 28-joint counts, patient reported outcomes, inflammatory tests and activity scores (DAS28-ESR, SDAI) performed every three months, while total and IgA-RF and ACPA every six months. The primary outcome measure was SDAI remission (≤ 3.3). Univariate and multivariate logistic regression models were used to estimate the association between baseline variables and SDAI remission at 12 months, using SPSS-16 software, p<0.05.

Results 39.7% of RA achieved SDAI remission after 12 months of anti-TNFs. Baseline levels of autoantibodies in subgroup analysis were 182.3IU/ml for total RF, 14.4IU/ml for IgA-RF and 75.7 IU/ml for ACPA, respectively. Statistically significant moderate correlation between SDAI remission and baseline IgA-RF (Spearman: r=0.321, p=0.002), as well as weak correlation with ACPA (Sperman: r=0.194, p=0.047) were reported, while no correlation with total initial RF levels (Sperman: r=0.021, p=0.844). Furthermore, patients with baseline levels of total RF ≤100IU/ml (OR 1.09; IC95% 0.45-2.61), ACPA ≤40IU/ml(OR 1.99; IC95% 0.95-4.17) and IgA-RF ≤20IU/ml(OR 5.76; IC95% 1.43-23.23) were more likely to achieve SDAI remission.

Conclusions The presence as well as the titer of IgA-RF isotype and ACPA before starting anti-TNFα therapy were significantly correlated with SDAI remission at 12 months. However, this correlation is not strong enough to allow a reliable prediction in individual patients.

Disclosure of Interest None Declared