Serological bone markers and joint damage in early polyarthritis

Objective. To investigate the relationship between osteocalcin (OC), a marker of bone formation, and the recently developed serum marker of bone resorption, β-C-telopeptide (β-CTx), and radiographic damage in patients with early oligo- and polyarthritis. Methods. Patients with peripheral arthritis of ≥ 2 joints and < 2 years of symptom duration were studied. The OC and β-CTx concentrations at baseline were correlated with disease activity and radiographic damage at baseline, and with radiographic progressive disease after 2 years (delta Sharp/van der Heijde score ≥ 5). The additional value of serum bone metabolism markers to predict radiographic progressive disease was compared to that of established prognostic factors by multivariate logistic regression analysis. Results. Two hundred seventy-nine patients (67% female; median age 56 yrs, range 18-83) were included in the study, of whom 73% were diagnosed with rheumatoid arthritis (RA). Baseline levels of β-CTx (p < 0.05) were significantly correlated with baseline radiographic damage whereas OC was not. β-CTx was also significantly (p < 0.001) related to measures of disease activity like erythrocyte sedimentation rate, C-reactive protein, and the disease activity score DAS28. Radiographic progressive disease after 2 years corresponded univariately with increased levels of β-CTx (p < 0.001), but not with OC. In multivariate analysis, β-CTx was not superior to other measures of radiographic progressive disease such as autoantibodies and disease activity. Conclusion. Increased serum levels of the bone turnover marker β-CTx are associated with radiographic damage at baseline and radiographic progression after 2 years. However, β-CTX is less predictive than markers already in use.