title: Urinary levels of type II collagen C-telopeptide crosslink are unrelated to joint space narrowing in patients with knee osteoarthritis.
abstract: OBJECTIVE
  To determine whether urinary concentrations of the cross linked C-telopeptide of type II collagen (CTx-II) distinguish subjects with progressive radiographic or symptomatic knee osteoarthritis from those with stable disease.
  
  
  METHODS
  
  
  
  METHODS
  were 120 obese women with unilateral knee osteoarthritis who participated in a 30 month, randomised, placebo controlled trial of structure modification by doxycycline, in which a standardised semiflexed anteroposterior view of the knee was obtained at baseline and 30 months. Subjects were selected from a larger sample to permit comparisons of urinary CTx-II levels between 60 progressors and 60 non-progressors with respect to medial joint space narrowing. Each group contained 30 subjects who, across five semi-annual assessments, reported on at least two occasions an increase of > or =20% in 50 ft walk pain (minimum = 1 cm on a 10 cm visual analogue scale), relative to the previous visit. The remainder reported no increases in knee pain. Urine samples were obtained semi-annually for determination of the CTx-II and creatinine concentrations.
  
  
  RESULTS
  In an analysis of the placebo group only, the frequency of radiographic progressors in the upper and middle tertiles (48% and 60%, respectively) of the baseline CTx-II distribution was not significantly different than that in the lower tertile (64%). These results were unchanged after inclusion of data from subjects in the doxycycline group. Furthermore, serial CTx-II levels did not distinguish subjects with progressive radiographic or symptomatic knee osteoarthritis from those with stable disease.
  
  
  CONCLUSIONS
  In this pilot study, urinary CTx-II concentration was not a useful biomarker of osteoarthritis progression.
authors.affiliation: Indiana University School of Medicine, Department of Medicine, Rheumatology Division, Long Hospital Room 545, 1110 W Michigan St, Indianapolis, IN 46202-5100, USA. smazzuca@iupui.edu
authors.forename: S A
authors.initials: SA
authors.lastname: Mazzuca
authors.forename: K D
authors.initials: KD
authors.lastname: Brandt
authors.forename: D R
authors.initials: DR
authors.lastname: Eyre
authors.forename: B P
authors.initials: BP
authors.lastname: Katz
authors.forename: J
authors.initials: J
authors.lastname: Askew
authors.forename: K A
authors.initials: KA
authors.lastname: Lane
mesh_terms: D015415:Biomarkers / Q000652:urine; D016022:Case-Control Studies; D024043:Collagen Type II / Q000652:urine*; D018450:Disease Progression; D004318:Doxycycline / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D016018:Least-Squares Analysis; D008875:Middle Aged; D009765:Obesity / Q000150:complications / Q000000981:diagnostic imaging / Q000652:urine; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000652:urine*; D010446:Peptide Fragments / Q000652:urine*; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011859:Radiography
chemical_list: D015415:Biomarkers; D024043:Collagen Type II; D010446:Peptide Fragments; D004318:Doxycycline