title: Change in serum measurements of cartilage oligomeric matrix protein and association with the development and worsening of radiographic hip osteoarthritis.
abstract: OBJECTIVE
  To determine the association between changes in serum levels of cartilage oligomeric matrix protein (COMP) and serum N-telopeptide crosslinks (NTX) over a 6-year interval with the development and progression of radiographically apparent hip osteoarthritis (RHOA) in a community sample of elderly women over 8.3 years of follow-up.
  
  
  METHODS
  Pelvic radiographs were obtained a mean of 8.3 years apart in Caucasian women > or =65 years of age enrolled in the Study of Osteoporotic Fractures. From a cohort of 5928 subjects, we randomly sampled study subjects ( approximately 170 per group) to perform two nested case-control studies, one of RHOA incidence and the other of RHOA progression. Baseline and year 6 serum COMP and serum NTX levels were measured by enzyme linked immunosorbent assay in duplicate and percentage change in serum levels was calculated. Odds ratios (ORs) and 95% confidence intervals (CIs) for 1 standard deviation (SD) change in the serum COMP and NTX level differences were calculated using logistic regression analysis and used to predict the development or progression of RHOA, adjusting for potential covariates.
  
  
  RESULTS
  The percentage change in the level of serum COMP from baseline to year 6 was found to be a risk factor for the development of incident RHOA [adjusted OR of 1.58 per 1 SD increase (95% CI: 1.19-2.09)], and reduction of progression of RHOA [adjusted OR of 0.74 per 1 SD increase (95% CI: 0.58-0.96)]. Quartile analysis of serum COMP changes revealed that the three highest quartiles of change in serum COMP were associated with (1) a five-fold greater risk of developing incident RHOA [adjusted OR=5.42 (95% CI: 2.80-10.60)], and (2) a 50% decreased risk of developing progression of RHOA [adjusted OR=0.48 (95% CI: 0.30-0.80)]. No significant association was found between changes in serum NTX levels from baseline to year 6 with either incident RHOA or the progression of existing RHOA.
  
  
  CONCLUSIONS
  Measurement of serum COMP at two distinct timepoints may be a method of identifying patients at risk for developing incident RHOA and those with baseline RHOA that will not rapidly progress.
authors.affiliation: New York Presbyterian Hospital, Weill Cornell Medical College, New York, NY, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Chaganti
authors.forename: A
authors.initials: A
authors.lastname: Kelman
authors.forename: L
authors.initials: L
authors.lastname: Lui
authors.forename: W
authors.initials: W
authors.lastname: Yao
authors.forename: M K
authors.initials: MK
authors.lastname: Javaid
authors.forename: D
authors.initials: D
authors.lastname: Bauer
authors.forename: M
authors.initials: M
authors.lastname: Nevitt
authors.forename: N E
authors.initials: NE
authors.lastname: Lane
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D064236:Cartilage Oligomeric Matrix Protein; D016022:Case-Control Studies; D024042:Collagen Type I / Q000097:blood; D018450:Disease Progression; D016326:Extracellular Matrix Proteins / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D064235:Matrilin Proteins; D015207:Osteoarthritis, Hip / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D010455:Peptides / Q000097:blood; D011379:Prognosis; D011859:Radiography
chemical_list: D015415:Biomarkers; D064236:Cartilage Oligomeric Matrix Protein; D024042:Collagen Type I; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D064235:Matrilin Proteins; D010455:Peptides; C577553:TSP5 protein, human; C052929:collagen type I trimeric cross-linked peptide