Role of Serum cartilage oligomeric matrix protein (COMP) in the diagnosis of rheumatoid arthritis (RA): A case–control study

OBJECTIVE To analyse the role of serum cartilage oligomeric matrix protein (COMP) levels in the differential diagnosis of rheumatoid arthritis (RA). METHODS This case-control study analysed the clinical and laboratory characteristics of patients with RA and healthy control subjects. The diagnostic ability of COMP for RA was evaluated by comparing it with anti-cyclic citrullinated peptide antibody levels. The sensitivity, specificity, positive and negative predictive values were calculated. RESULTS The study enrolled 82 patients with RA and 34 healthy control subjects. The serum COMP level was significantly higher in patients with RA compared with control subjects (mean ± SD 29.51 ± 9.21 ng/ml versus 17.85 ± 5.55 ng/ml, respectively). The serum COMP level was significantly higher in patients with active RA compared with patients with RA in remission (mean ± SD 33.08 ± 8.80 ng/ml versus 24.94 ± 7.65 ng/ml, respectively). The cut-off value for COMP to discriminate patients with RA from healthy individuals was 21.51 ng/ml (sensitivity 0.817, specificity 0.882, positive predictive value 0.944, negative predictive value 0.667, and accuracy 0.836). CONCLUSION The serum COMP level has the potential to be used as a biological marker for differentiating between patients with RA and healthy individuals.