Low incidence of rheumatoid factor and autoantibodies in Nigerian patients with rheumatoid arthritis.

Sera from 53 Nigerian patients satisfying the American Rheumatism Association criteria for a diagnosis of definite or probable rheumatoid arthritis and sera from sick and healthy Nigerian controls were tested for rheumatoid factor, autoantibodies, and immunoglobulin levels. Rheumatoid factor and autoantibodies were found no more frequently in patients with rheumatoid arthritis than in controls. These findings confirm the clinical impression that Nigerian patients with polyarthritis satisfying the criteria for a diagnosis of rheumatoid arthritis differ from Caucasian patients with the disease in a number of important respects. They suggest that either these patients do not have rheumatoid arthritis but a distinct clinical syndrome or that in Nigeria the course of rheumatoid arthritis is modified by genetic or environmental factors.