Abstract

The clinical features of a group of 79 patients with older age onset rheumatoid arthritis (ORA) were compared with those of a group of 414 patients with younger age onset rheumatoid arthritis. The ORA group contained approximately equal numbers of men and women, were less rheumatoid factor positive, had a raised erythrocyte sedimentation rate, lower HLA-DR4 positivity, and a tendency towards larger joint involvement at the onset of the disease. These features have been reported by many authors except for the lower DR4 positivity. Of these features, the lower prevalence of rheumatoid factor positivity and the tendency towards larger joint involvement at the onset were characteristic of a subset of patients with ORA who had had osteoarthritis before the onset of rheumatoid arthritis. It is suggested that osteoarthritic large joints may be susceptible to the occurrence of rheumatoid synovitis at the onset of the disease, but that the osteoarthritis inducing factor may be negatively related to the progression of rheumatoid arthritis.