IgG rheumatoid factor in early rheumatoid arthritis as a predictor of radiological changes and disease activity

Our objective was to confirm whether IgG rheumatoid factor (IgG RF) assessed in early rheumatoid arthritis (RA) could be a prognostic factor of disease activity and articular destruction. The IgG RF index was assessed by a kit (Eitest IgG RF) in 46 patients with early RA (disease duration less than 1 year). Damage score (DS), carpal height ratio (CHR), clinical variables, and conventional RF values were evaluated at the initial visit and 2–3 years (average 2.5 years) after the initial visit. The incidence of IgG RF was 23.9% at the initial visit. Patients with positive IgG RF showed higher DS and higher Lansbury’s index in the final observation. They also showed a greater increase of DS and a greater decrease of CHR. The IgG RF index correlated with the final DS and final Lansbury’s index. We conclude that although the incidence was low, the IgG RF index in early RA could be a prognostic factor in radiographic changes and disease activity 2–3 years after the initial visit.