OBJECTIVE; Several factors predict joint damage in early rheumatoid arthritis (RA). In the context of a trial in early RA, we studied the relationship between clinical signs in individual joints and their propensity to develop progressive damage.
The COBRA (Combinatietherapie Bij Reumatoide Artritis) multicenter trial compared the efficacy of prednisolone, methotrexate, and sulfasalazine against sulfasalazine alone in 155 patients with early RA. Two blinded observers interpreted radiographs in sequence (using the Sharp/Van der Heijde scoring system); in each center, one blinded observer performed clinical assessments every 3 months. The current analysis is based on clinical and radiologic data of the individual metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints of 135 patients. Conditional stepwise logistic regression analyzed the relationship between damage (progression) and clinical signs at baseline and followup for each of these joints individually in each patient.
Combination therapy strongly retarded the progression of damage. Progression was stronger in patients with rheumatoid factor, HLA-DR4, and high levels of disease activity at baseline. At baseline, 6% of the MCP and PIP joints showed damage; after 1 year, disease had progressed in 10% of these joints. Baseline damage, swelling, or pain in a joint independently and strongly predicted the progression of damage in that joint (P < 0.001). Each additional point in the swelling score (range 0-2) tripled the risk for subsequent progression. Each additional point on the Sharp scale (range 0-8 per joint) and each additional point on the pain scale (range 0-3) doubled the risk. The mean pain and swelling scores over the year were even stronger predictors of damage.
Local expression of early RA disease activity, both at baseline and at 1-year followup, is strongly related to progression of damage in the individual joint.