The lupus patient with positive rheumatoid factor

Background Patients with systemic lupus erythematosus (SLE) may form clusters with clinical manifestations and autoantibodies. Objective The objective of this report is to study whether SLE patients with positive rheumatoid factor (RF) have a special clinical and/or serological profile. Methods A retrospective study of 467 SLE patients seen at a single rheumatology unit was conducted. Epidemiological data (age, gender, age at disease onset, ethnic background and tobacco use), clinical data (malar rash, photosensitivity, oral ulcers, discoid lesions, serositis, glomerulonephritis, convulsions, psychosis, hemolytic anemia, leukopenia, lymphocytopenia, arthritis and hypothyroidism) and serological profile (anti-dsDNA, anti-Ro/SS-A, anti-La/SS-B, anti-RNP, anti-Sm, IgG aCL, IgM aCL, lupus anticoagulant, direct Coombs and RF) were collected. Patients with positive and negative RF were compared. Results RF was found in 24.9% of the sample. In univariate analysis, RF was positively associated with butterfly rash ( p = 0.04), anti-Ro ( p = 0.03), anti-Sm antibodies ( p = 0.01) and hypothyroidism ( p = 0.01) and negatively associated with glomerulonephritis ( p = 0.003). Logistic regression showed that only glomerulonephritis ( p = 0.03; OR = 0.45; 95% CI = 0.21-0.93) and anti-Ro ( p = 0.009; OR = 2.3; 95% CI = 1.24-4.57) were independent associations. Conclusion In our sample RF was associated with protection from glomerulonephritis and with higher prevalence of anti-Ro antibodies.