Background Recent report indicates that the presence of anti-SS-A antibodies are an independent factor associated with an insufficient response to tumour necrosis factor (TNF) inhibitors in patients with rheumatoid arthritis (RA) (Ref. 1). Since anti-SS-A antibodies are frequently found in patients with RA (20%), other classes of biologic disease modifying anti-rheumatic drugs (DMARDs) than TNF inhibitors may be indicative for active anti-SS-A antibodies-positive RA patients.
Objectives To investigate whether abatacept (ABT) is effective for anti-SS-A antibodies-positive RA patients comparing with anti-SS-A antibodies-negative RA patients.
Methods This is a prospective observational study and consists of 50 RA patients (42 females and 8 males) who had been administrated with ABT. Eighteen patients were anti-SS-A antibodies-positive whereas 32 were anti-SS-A antibodies-negative, respectively. Patients gave their informed consent to be subjected to the protocol. We have selected the anti-SS-A antibodies-negative RA patients whose baseline variables, including disease duration and clinical disease activity at baseline, were comparable with anti-SS-A antibodies-positive RA patients. The continuation rate and clinical disease activity including SDAI were evaluated during 6 months treatment of ABT. Statistical analysis included last observation carried forward (LOCF) method.
Results At baseline, there was no statistical difference of SDAI in both groups: 20.47 in the anti-SS-A antibodies-positive RA group and 21.92 in the anti-SS-A antibodies-negative RA group, respectively (p =0.9554, Student's t test). At 6 months, although there was no statistically significant difference between the 2 groups, SDAI tended to be lowered in the anti-SS-A antibodies-positive RA group as compared with anti-SS-A antibodies-negative RA group (9.11 in the former vs 12.11 in the latter, p =0.2036, Welch's t test). It is interesting to note that the discontinuation rate for ABT due to lack of efficacy or adverse events at 6 months was significantly lower in anti-SS-A antibodies-positive RA group as compared with anti-SS-A antibodies-negative group (p =0.0475, Welch's t test).
Conclusions In comparison with TNF inhibitors, the present data suggest that ABT is a suitable biologic DMARDs in patients with anti-SS-A antibodies-positive RA.
Matsudaira R, Tamura N, Sekiya F, et al. Anti-Ro/SSA antibodies are an independent factor associated with an insufficient response to tumor necrosis factor inhibitors in patients with rheumatoid arthritis. J Rheumatol 2011; 38: 2346-54.
Disclosure of Interest None declared