Association of baseline levels of markers of bone and cartilage degradation with long-term progression of joint damage in patients with early rheumatoid arthritis

Objective The known risk factors for radiologic progression in rheumatoid arthritis (RA) are not optimally discriminative in patients with early disease who do not have evidence of radiologic damage. We sought to determine whether urinary C-terminal crosslinking telopeptide of type I (CTX-I) and type II (CTX-II) collagen (markers of bone and cartilage destruction, respectively) are associated with long-term radiologic progression in patients with early RA. Methods This was a prospective study of 110 patients with early RA who were participating in the COBRA (Combinatietherapie Bij Reumatoide Artritis) clinical trial and followup study, a randomized controlled trial comparing the efficacy of oral pulse prednisolone, methotrexate, plus sulfasalazine with sulfasalazine alone. We investigated the relationship between baseline levels of urinary CTX-I and CTX-II and the mean annual progression of joint destruction over a median of 4 years, as measured by changes in the modified Sharp score (average of 2 independent readers). Results In multivariate logistic regression analysis, baseline urinary CTX-I and CTX-II levels in the highest tertile were the strongest predictors of radiologic progression (Sharp score increase >2 units/year; odds ratio 7.9 and 11.2, respectively), independently of treatment group, erythrocyte sedimentation rate (ESR), Disease Activity Score in 28 joints, rheumatoid factor (RF), and baseline joint damage (Sharp score). The likelihood ratios for a positive test were 3.8 and 8.0 for CTX-I and CTX-II, respectively, which compared favorably with the likelihood ratios for the ESR (3.0), baseline joint damage (1.6), and RF (1.8). When patients were grouped according to the presence (Sharp score ≥4, n = 49) and absence (Sharp score