Joint damage is related to disease activity in rheumatoid arthritis (RA), but the degree of its progression and the temporal associations between disease activity and joint damage are unclear. The aim of this study was to evaluate whether there is a latency in the effect of disease activity on radiographic progression in patients with RA.
Data were obtained from the PREMIER trial, a 2-year randomized, controlled clinical trial of adalimumab plus methotrexate versus methotrexate alone or adalimumab alone in early RA. Radiographic progression of joint damage was calculated using the modified total Sharp score in a subset of patients whose disease was in remission (Simplified Disease Activity Index<or=3.3) in the second year of the trial. The progression of damage in the second year was compared between groups of patients whose disease was already in remission for an additional period of 3, 6, or 9 months during the first year. Analysis of variance was used to test for a linear trend.
Among 794 patients with early RA, 119 (15%) achieved sustained remission during the second year, with no difference in radiographic progression across the 3 treatment groups. Radiographic progression in the second year was significantly different between patients with 3, 6, or 9 additional months of remission during year 1 (mean change in the modified Sharp score 1.19 in those with 3 additional months of remission versus 0.20 in those with 6 additional months of remission and -0.32 in those with 9 additional months of remission; P<0.05). The results were supported by similar findings in a series of sensitivity analyses.
These data indicate that the level of disease activity as well as the duration of remission affect subsequent progression of radiographic damage in RA. This latency between disease activity and its effects on radiographic progression should be considered when evaluating radiographic outcomes in trials of RA.