Serum levels of YKL-40 and C reactive protein in patients with hip osteoarthritis and healthy subjects: a cross sectional study
- Th Conroziera,
- M-C Carlierb,
- P Mathieua,
- F Colsona,
- A L Debardc,
- S Richarda,
- H Favreta,
- J Bienvenuc,
- E Vignona
- aDepartment of Rheumatology, Centre Hospitalier Lyon-Sud, Pierre-Bénite, France, bDepartment of Biochemistry, Centre Hospitalier Lyon-Sud, cDepartment of Immunology, Centre Hospitalier Lyon-Sud
- Dr Thierry Conrozier, Service de rhumatologie, Centre hospitalier Lyon-Sud, 165 chemin du Grand-Revoyet, 69495 Pierre-Bénite cedex, France Email:th.conrozier{at}wanadoo.fr
- Accepted 24 February 2000
Abstract
BACKGROUND YKL-40 is a 40 kDa glycoprotein secreted by chondrocytes and synoviocytes. It has been suggested that it is a surrogate marker of synovial inflammation and joint destruction in rheumatoid arthritis (RA) and osteoarthritis (OA) and related to C reactive protein (CRP) serum levels in RA.
OBJECTIVE To study serum levels of YKL-40 in patients with hip OA and its relation with CRP.
METHODS YKL-40 and CRP were assayed in serum samples from 45 patients (24 women, 21 men, mean age 65) with symptomatic OA of the hip and 33 healthy controls. YKL-40 was assayed by immunoassay and CRP by ultrasensitive immunonephelometry. OA severity was assessed by the measurement of joint space width with a computer analysis system of digitised hip radiographs. Statistical analysis was performed to determine correlations between serum markers and radiological joint space width.
RESULTS The mean (standard error) YKL-40 level was 90.3 (8.2) ng/ml in patients with hip OA and 66.9 (8.2) ng/ml in controls (p=0.03). The mean CRP level was 2.93 (3.03) mg/l in OA and 1.40 (1.61) mg/l in controls (p=0.006). The serum levels of YKL-40 and CRP increased with age and were significantly correlated (Spearman test:rs=0.42, p=0.005) in patients but not in controls. Neither YKL-40 nor CRP correlated with radiographic joint space width.
CONCLUSIONS Serum YKL-40 was significantly increased in patients with hip OA. The correlation between YKL-40 and CRP suggests that YKL-40 may be a marker of joint inflammation in OA. Longitudinal studies are required to assess the usefulness of YKL-40 in the monitoring of patients with hip OA.
