Meta-analysis of serum C-reactive protein and cartilage oligomeric matrix protein levels as biomarkers for clinical knee osteoarthritis

Junfeng Zhang

The roles of C-reactive protein (CRP) and cartilage oligomeric matrix protein (COMP) in knee osteoarthritis (KOA) remain controversial, thus the present study is aimed to explore the relationships between CRP, COMP, and the incidence/progression of KOA. A systematic search was conducted on PubMed and Embase until September, 2016 for all the relevant studies. The pooled mean difference (MD) with its 95% confidence interval (95% CI) based on fixed effects model or random effects model was calculated to assess the potential role of CRP and COMP in the incidence or progression of KOA. Heterogeneity was evaluated by Cochran's Q and I2 tests. When P < 0.05 or I2 > 50%, a random effects model was chosen, otherwise, a fixed effects model was used. Moreover, the role of CRP in different degrees of pain was also analyzed. Sensitivity analysis was performed to evaluate the strength of the meta-analysis. Fourteen studies were enrolled in the meta-analysis. No difference was found between baseline CRP and CRP levels in the last follow-up period of KOA (MD = - 0.09, 95% CI: -0.30, 0.13). Pooled data showed higher CRP concentration in patients with incident KOA when compared with controls (MD = 0.33, 95% CI: 0.04, 0.63). Moreover, higher serum COMP levels were found in patients with incident KOA (MD = 1.69, 95% CI: 0.61, 2.76) Additionally, significant higher CRP concentration was observed in KOA patients with highest degree of pain (MD = 1.60, 95% CI: 0.52, 2.67). CRP and COMP serum levels were both associated with the incidence of KOA. Patients with a higher CRP and COMP concentration might have an increased probability of developing KOA. However, higher CRP serum levels was not related with KOA progression. Furthermore, KOA patients with more pain had higher CRP concentrations.