Serum cartilage oligomeric matrix protein reflects osteoarthritis presence and severity: The Johnston county osteoarthritis project

Open Access
Publisher Website
Google Scholar
Abstract
Objective To characterize serum cartilage oligomeric matrix protein (COMP) levels by age and gender for a radiographically defined population free of hip and knee osteoarthritis (OA), and to examine the potential utility of COMP as a diagnostic biomarker for knee OA. Methods Serum samples and knee and hip radiographs were obtained at a baseline evaluation as part of the Johnston County Osteoarthritis Project, a population‐based study of OA in rural North Carolina. A total of 291 Caucasian participants were randomly selected for COMP analysis, 143 patients with radiographic knee OA (Kellgren/Lawrence [K/L] grade ≥2) and 148 controls with neither hip nor knee OA (K/L grade 0), evenly distributed by age and gender. COMP was quantified by competitive enzyme‐linked immunosorbent assay with monoclonal antibody 17‐C10. The natural log–transformed COMP data were analyzed using general linear models. Results Serum COMP levels were significantly elevated (P = 0.0001) in the age ≥65 group (mean ± SD 1,302.1 ± 496.7 ng/ml) versus the age 45–54 and age 55–64 groups (1,058.1 ± 432.4 and 1,038.6 ± 313.3, respectively). Serum COMP levels of the OA group were significantly higher than those of the control group (1,208.57 ± 487.47 ng/ml versus 1,061.83 ± 370.58 ng/ml; P = 0.0093). Serum COMP levels also increased significantly with knee OA K/L grade (P = 0.0047), knee OA laterality (P = 0.0043), and number of knee and hip joints involved (P = 0.0001). There was no significant difference in serum COMP levels by gender or obesity. Conclusion We demonstrate that in a population‐based sample, serum COMP levels can distinguish an OA‐affected subgroup from an unaffected subgroup and can reflect disease severity and multiple joint involvement in OA.