Clinical correlations with IgG-rheumatoid factor (IgG-RF) were evaluated in 41 patients with rheumatoid arthritis (RA). The patients with positive IgG-RF with disease duration of less than two years showed increased levels in ESR, C-reactive protein, serum IgG concentrations and Lansbury's index, but they had neither extra-articular disorders nor vascular damage. However, four of eight patients with positive IgG-RF with disease duration of over five years had extra-articular disorders and vascular damage (especially interstitial pneumonia). In one early RA patient with positive IgG-RF who showed decreased levels of ESR and C-reactive protein and serum IgG concentrations, a high titer of IgG-RF was revealed over six months and joint damage progressed. In conclusion, we suggested that measurment of IgG-RF is useful in the clinical evaluation of rheumatoid arthritis associated with extra-articular disorders, vascular damage, and joint damage progression.
