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: Subjects 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 ⩾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.
- BMI, body mass index
- CTx-II, type II collagen C-terminal cross linked peptide
- JSN, joint space narrowing
- JSW, joint space width
- RCT, randomised controlled trial
- uCr, urinary creatinine concentration
- knee osteoarthritis
- osteoarthritis biomarkers
- type II collagen
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Published Online First 8 December 2005
Supported in part by NIH grants R01 AR43348, R01 AR43370, R01 AR37318, and P60 AR20582.