Evaluation of the prognostic value of immunogenetic markers in early rheumatoid arthritis (RA).
Ninety-nine patients with definite RA and disease duration 24 months or less were followed with standardized assessment. Disability was assessed by the HAQ index and radiographic changes in hands and feet by the Larsen method. The frequencies of HLA-DR genes were determined by serological typing, Gm allotype distribution by classical hemagglutination inhibition test, and occurrence of anti-Gm allotypes by use of anti-Rh coats. The immunogenetic findings were related to disease severity after 2 years' followup.
Functional capacity was well preserved, disease activity was less, but radiographic changes in hands and feet had increased considerably at study finish. A group of 13 patients had developed rapidly progressive changes of hip and/or shoulder joints, all requiring arthroplasty. There was a significantly increased frequency of HLA-DR4. Twenty-seven of the 68 HLA-DR4 positive patients were putatively homozygous. HLA-DR4 was not related to disability or to severe small joint destruction. However, progressive large joint damage was significantly more prevalent in homozygous patients (p < 0.01). Gm allotype distribution was normal and not related to clinical findings. Anti-Gm antibodies were common and frequently specific for nonhost Gm allotype. Fifty-six patients carried anti-G1m(a), and occurrence of this antibody was significantly associated with radiographic progression of small joints (p = 0.01), presence of nodules (p < 0.01) and number of active joints (p = 0.001).
Immunogenetic markers aided in identifying patients with early RA with more severe disease.