Prevalence of antiphospholipid antibodies in rheumatoid arthritis patients and relationship with disease activity.

INTRODUCTION It is still unclear how important the presence of antiphospholipid antibodies (aPL) is in patients with rheumatoid arthritis (RA). OBJECTIVES The aim of the study was to assess the prevalence of selected aPL in RA patients and their correlation with the presence of markers for RA antibodies and with disease activity. PATIENTS AND METHODS The study group consisted of 97 patients with RA who had never been treated with biological agents. In all patients, serum anticardiolipin antibodies (aCL), anti‑β2‑glycoprotein I antibodies (a‑β2‑GPI), lupus anticoagulant (LAC), immunoglobulin M (IgM) rheumatoid factor (RF), and anticyclic citrullinated peptide antibodies (anti‑CCP) were measured and disease activity was assessed. RESULTS The presence of aPL was observed in 27 patients (27.8%): aCL in 20 patients (20.6%), a‑β2‑GPI in 12 patients (12.4%), and LAC in 1 patient (1%). Positive aCL of low or medium levels were detected in the IgM class in 11 patients (11.3%) and in the IgG class in 12 patients (12.5%). Positive a‑β2‑GPI of low and medium levels were found only in the IgM class. The presence of LAC was associated with aCL‑IgM and a‑β2‑GPI‑IgM. A significant correlation was observed between the presence of anti‑CCP and different types of aPL. There was no correlation between aPL and IgM‑RF or disease activity markers. CONCLUSIONS The prevalence of aPL in patients with RA is relatively high. There is a relationship between the prevalence of aPL and anti‑CCP-serological marker of RA, but there are no significant correlations between disease activity and the presence of aPL.