Background Cartilage oligomeric matrix protein (COMP) is a major non-collagenous component of cartilage that accounts for approximately 1% of the wet weight of articular tissue.
Objectives To assess the COMP levels in serum and synovial fluid in early and established rheumatoid arthritis (RA) patients and correlate the levels with clinical, laboratory and radiological characteristics.
Methods Twenty-four female RA patients were included. Full history taking, thorough clinical examination and laboratory investigations were performed and the body mass index (BMI) recorded. Radiological damage was assessed according to the modified Larsen score. Disease activity score-28 (DAS-28) was calculated. Thirty age and sex matched subjects constituted the control. The serum COMP level was determined by ELISA.
Results The patients' age was 44.04±10.5 years. Twelve had early RA and another 12 had established disease with joint destruction; 5 of each group had knee effusion. The serum COMP was significantly higher in the patients (19.54±5.47μg/ml) compared with the control (5.93±1.95μg/ml) (p<0.001). It was significantly higher in the patients with established disease (23.9±3.1μg/ml) compared to early ones (15.1±3.2μg/ml) (p<0.001). Synovial COMPA was also significantly increased in established cases compared to early (31.2±9.8μg/ml vs 51.6±10.4μg/ml, p=0.013). The serum and synovial COMP significantly correlated with the age, disease duration, BMI, DAS28 and modified Larsen score. On performing the regression analysis in the RA patients, only the BMI could predict the serum level of COMP (p=0.02).
Conclusions In conclusion, COMP is a promising biomarker of disease activity in RA making it a potential therapeutic target. The obvious correlation with the body mass index throws light on the importance of weight control not only in OA but in RA.
Disclosure of Interest None declared