HLA-B27 antigen and rheumatoid factor negative (seronegative) peripheral arthritis : Studies in younger patients with early-diagnosed arthritis

HLA-B27, a valuable genetic marker for spondyloarthritis, offers a means for improved definition of rheumatoid factor negative (seronegative) peripheral arthritis. A group of 109 early-diagnosed patients with seronegative peripheral arthritis, who were under 45 years of age at the onset of disease, were studied prospectively. HLA-B27 prevalence was 23 per cent in the total group (25 of 109) and in those initially diagnosed as having rheumatoid arthritis (seven of 30) as compared to 7 per cent in normal subjects (six of 91). The age at onset of B27-associated arthritis was significantly concentrated in those 12 to 24 years of age (p < 0.005), especially in black males. The 25 patients who had the B27 antigen were matched on selected entry variables with 25 patients who did not. Clinical features and laboratory results were highly similar at entry to study and after three years average follow-up, with one exception found at the last examination. A striking prevalence of 83 per cent roentgenologic sacroiliitis was found in patients who had HLA-B27 compared to 21 per cent in those who did not, despite a paucity of spinal manifestations in both groups. These data emphasize the predominance of roentgenologic sacroiliitis in a varied spectrum of B27-associated arthritis, i.e., peripheral as well as spinal. The spectrum of seronegative peripheral arthritis includes an important subgroup who have B27, especially those with onset in adolescence or the early twenties. Clinical manifestations are often indistinguishable from matched patients without B27 and they may be frequently diagnosed as having seronegative rheumatoid arthritis during the early course of disease.