Sakthiswary R, et al. - The specialists examined the association of serum cartilage oligomeric matrix protein (COMP) levels with articular cartilage damage based on sonographic knee cartilage thickness (KCT) and disease activity in rheumatoid arthritis (RA). They concluded that the serum COMP was a promising biomarker in RA which reflects disease activity and damage to the articular cartilage.

• This study included 61 RA patients and 27 healthy controls.
• From all subjects, serum samples were obtained to determine the serum COMP levels.
• All subjects had bilateral ultrasound scan of their knees.
• The KCT was based on the mean of measurements at 3 sites: the medial condyle, lateral condyle and intercondylar notch.
• The RA patients were assessed for their disease activity based on 28-joint-based Disease Activity Score (DAS 28).
• In the RA patients compared, serum COMP concentrations were significantly elevated compared to the controls (p = 0.001).
• The serum COMP levels had an inverse relationship with bilateral KCT in RA subjects and the healthy controls.
• COMP correlated significantly with disease activity based on DAS 28 (r = 0.299, p = 0.010), disease duration (r = 0.439, p = < 0.05) and mean left KCT (r = - 0.285, p = 0.014) in RA.
• The association between serum COMP and DAS 28 scores was comparable to the traditional markers of inflammation: erythrocyte sedimentation rate (ESR) (r = 0.372, p = 0.003) and C-reactive protein (CRP) (r = 0.305, p = 0.017).