Relationship between time-integrated C-reactive protein levels and radiologic progression in patients with rheumatoid arthritis

Objective. An elevated acute-phase response is associated with increased ra diologic damage in rheumatoid arthritis (RA), but development of damage in previously normal joints ("new joint involvement") has not previously been investigated. This study was undertaken to investigate the hypothesis that when there is suppression of disease activity as judged by the C-reactive p rotein level, new joint involvement is reduced to a greater extent than is progression in already damaged joints ("damaged joint progression"). Methods. Three hundred fifty-nine patients,vith active RA were studied as p art of a 5-year randomized, prospective, open-label study of disease-modify ing antirheumatic drug therapy. Time-averaged CRP was calculated from sampl es obtained every 6 months, and patients were divided into groups with CRP values of <6, 6-<12, 12-<25, and greater than or equal to 25 mg/liter, Radi ographs of the hands and feet were scored by the Larsen method; a damaged j oint was defined as one with a score of greater than or equal to 2. Results, The rank correlation between time-integrated CRP and increase in L arsen score was 0.50; the correlation increased to 0.59 for patients enteri ng the study with disease duration of less than or equal to 2 years. The pe rcentage of new joint involvement over 5 years varied markedly with time-in tegrated CRP, from 7.3% in the CRP <6 mg/liter group to 39.1% in the CRP gr eater than or equal to 25 mg/liter group (5.4-fold increase). The percentag e of damaged joint progression increased from 26.1% in the CRP <6 mg/liter group to 41.6% in the CRP greater than or equal to 25 mg/liter group (1.6-f old increase). Conclusion, The results of this study provide further confirmation that hig h CRP levels over time are associated with greater radiologic progression, Although radiologic progression still occurred in both previously normal an d damaged joints despite the presence of normal CRP levels, this consisted of proportionately less new joint involvement compared with damaged joint p rogression, These findings support the idea that disease-suppressive therap y should be instituted at an early stage in patients with RA, before erosiv e damage has occurred.