COMPARISON OF CYSTIC RHEUMATOID-ARTHRITIS AND EROSIVE RHEUMATOID-ARTHRITIS

Objective. To test the hypothesis that cystic rheumatoid arthritis (RA ), characterized as subchondral cysts as the only radiographic abnorma lity in hands and fret for 2 years after first abnormal radiograph, is a mild subset of RA. Methods. Fifty-four patients with cystic RA were compared with 144 RA controls matched for age, sex, disease duration, and year of first visit. All patients were randomly selected from a d atabase of 1580 patients with RA attending the clinic 1982-88. In 1994 , data of 90% of the patients were collected by one investigator, blin ded to the study groups. All available radiographs were scored for ero sions and cysts by one radiologist. Results. During 17 years of follow up (range 2-48 yrs), the cystic RA group had less severe disease. Ther e were fewer disease modifying antirheumatic drug prescriptions and fe wer orthopedic operations in the group with cystic RA. The proportion of Rose-Waaler seropositives and the proportion of patients with extra articular manifestations were the same for both groups. At final asses sment, the median Health Assessment Questionnaire score was significan tly lower for the group with cystic RA (0.88 vs 1.56; p < 0.01). The f inal radiographic score was significantly lower for the cystic RA grou p vs 0.58; p < 0.01). The outcome differences remained after correctin g for early radiographic score, rheumatoid factor, early erythrocyte s edimentation rate(ESR), and presence of comorbidity in a multiple regr ession model. Mortality was the same for both groups. Conclusion. Cyst ic RA is a relatively mild subset of RA.