To evaluate the clinical importance of the RA "shared epitope" (SE) as a prognostic marker of radiological severity and extension of the disease to large joints in patients with rheumatoid arthritis (RA).
Eighty-two patients who met the American College of Rheumatology criteria for RA with a disease duration < 2 years at presentation were included in the study. Radiographs of hands, wrists, feet, shoulders, elbows, hips, and knees were taken at study entry and 8-10 years later. HLA-DRB1 genotypes were determined by polymerase chain reaction-sequence-specific oligonucleotide probes. Radiological severity was assessed in small joints of hands, wrists, and feet. Extension of the disease to large joints was evaluated in radiographs of shoulders, elbows, hips, and knees.
At the end of the study, erythrocyte sedimentation rate (ESR), rheumatoid factor (RF) titer, and percentage of maximum radiological score at baseline were significantly associated with RA severity (p < 0.01, p < 0.01, p < 0.05, respectively). Extension of RA to large joints was related to a higher ESR (p < 0.001) and a lower hemoglobin level (p < 0.01) at baseline. Neither at entry nor at the end of the study was the RA shared epitope predictive for radiologic severity or extension of disease to large joints (p = 0.8, p = 0.3, respectively).
Presence of the SE in patients with RA is not a good prognostic marker of radiological severity after a mean followup period of 9 years.