Is the response to anti-TNFα treatment influenced by the presence of IgM rheumatoid factor, in Rheumatoid Arthritis patients?

Aim: To verify if the response to TNF alpha inhibitors is influenced by the presence of IgM rheumatoid factor (RF), in patients with RA. Material and Methods: In this study, the patients with the diagnosis of RA treated with TNF alpha inhibitors followed in our hospital were recruited. A protocol was applied including demographic, clinical and laboratory data, in order to calculate DAS 28. The presence/absence of IgM RF and associated therapies were record. Results: Fifty-seven patients, 52 female, with a mean duration of anti-TNF alpha treatment of 30,9 +/- 15,9 months were studied. Twenty-four patients were being treated with infliximab, 17 with adalimurnab and 16 with etanercept. Forty-one patients had IgM RF detectable in serum (RF positive group). In the RF positive group, the variation of DAS 28 was -1,75 +/- 1,53 us -1,04 +/- 1,76 in the RF negative group (P=0,135). The mean duration of anti-TNF alpha treatment was similar in both groups (31,9 +/- 15,9 vs 29,5 +/- 16,16 months). Patients who were treated with methotrexate presented a higher variation of DAS 28 (-1,87 +/- 1,70 vs -0,80 +/- 1,09; p=0,041) and this variation was dose dependent (p=0,056). Conclusions: Despite needing a replication in a larger cohort, our results suggest that the presence ofIgM RF in the serum did not interfere with the response to treatment with TNF alpha inhibitors.