title: Role of Serum cartilage oligomeric matrix protein (COMP) in the diagnosis of rheumatoid arthritis (RA): A case-control study.
abstract: 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).
  
  
  CONCLUSIONS
  The serum COMP level has the potential to be used as a biological marker for differentiating between patients with RA and healthy individuals.
authors.affiliation: Department of Rheumatology and Immunology, Weifang People's Hospital, Weifang City, Shandong Province, China.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Liu
authors.affiliation: Department of Rheumatology and Immunology, Weifang People's Hospital, Weifang City, Shandong Province, China.
authors.forename: Xijuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Rheumatology and Immunology, Weifang People's Hospital, Weifang City, Shandong Province, China.
authors.forename: Xude
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Haematology, Weifang People's Hospital, Weifang City, Shandong Province, China.
authors.forename: Cuiai
authors.initials: C
authors.lastname: Ren
authors.affiliation: Department of Orthopaedic Surgery, Weifang People's Hospital, Weifang City, Shandong Province, China aqlfx@163.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Xin
mesh_terms: D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000175:diagnosis* / Q000276:immunology; D064236:Cartilage Oligomeric Matrix Protein / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology; D012372:ROC Curve
chemical_list: D064236:Cartilage Oligomeric Matrix Protein; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide
keywords: Cartilage oligomeric matrix protein; anti-cyclic citrullinated peptide antibody; rheumatoid arthritis