Progression of radiographic joint damage in rheumatoid arthritis: independence of erosions and joint space narrowing.

OBJECTIVE: To compare the progression of erosions and joint space narrowing (JSN) in patients with early active rheumatoid arthritis (RA) using data obtained in the "Active-controlled Study of Patients receiving Infliximab for the treatment of Rheumatoid arthritis of Early onset" (ASPIRE) study.

METHODS: This was a post hoc analysis of patients in ASPIRE who received placebo plus methotrexate (MTX) or infliximab (3 or 6 mg/kg) plus MTX. Radiographs of the hands (870 patients) and feet (871 patients) were obtained at baseline and week 54 and scored using the van der Heijde/Sharp method. In total, 7160 joints in the placebo plus MTX group and 18,908 joints in the combined infliximab plus MTX group were included in this analysis.

RESULTS: At baseline, 83.4% of joints in the placebo plus MTX group had no radiographic damage, 8.5% had only erosions, 4.4% had only JSN and 3.7% had both. The distribution was similar in the infliximab plus MTX group. In the placebo plus MTX group, the majority of joints did not have development or progression of radiographic damage from baseline to week 54; among joints that did have development or progression of damage at week 54, erosions occurred more often than JSN. The same pattern was observed in the infliximab plus MTX group, although the proportions of joints with damage at week 54 were generally larger in the placebo plus MTX group. There was a tendency for joints with existing erosions or JSN to have progression of damage, rather than development of new damage.

CONCLUSIONS: Erosions were the predominant type of damage observed in both treatment groups. Erosions and JSN are related but partly independent processes.