Rheumatology Advance Access originally published online on March 26, 2007
Rheumatology 2007 46(6):938-943; doi:10.1093/rheumatology/kel409
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A 5-yr longitudinal study of type IIA collagen synthesis and total type II collagen degradation in patients with knee osteoarthritis—association with disease progression
1Department of Anatomy, University of Bristol 2Academic Rheumatology Unit, Bristol Royal Infirmary, Bristol, UK 3Molecular Markers, Synarc, Lyon, France 4Washington University School of Medicine, Department of Orthopaedic Surgery, St Louis, Missouri, USA 5Institut National de le Santé et de la Recherche Médicale (INSERM) Research Unit 664, Lyon, France
Correspondence to: M. Sharif, Department of Anatomy, University of Bristol, Southwell Street, Bristol BS2 8EJ, UK. E-mail: mo.sharif{at}bris.ac.uk.
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Abstract |
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Objectives. The 5-yr longitudinal study tested the hypothesis that serum and urinary markers of type II collagen metabolism would be associated with radiological progression of disease in patients with mild-to-moderate knee osteoarthritis (OA).
Methods. Synthesis of type IIA collagen and degradation of total type II collagen were assessed in 135 patients with mild-to-moderate knee OA over 5 yrs using serum concentration of the N-propeptide of collagen type IIA (PIIANP) and urinary excretion of crosslinked C-telopeptide (CTX-II), respectively. The markers were measured at baseline, 2, 3 and 5 yrs’ follow-up corresponding to X-ray time points. Analysis of variance (ANOVA) was performed to determine longitudinal changes over 5 yrs in the biomarkers in all patients and between progressors and non-progressors.
Results. Complete X-ray progression data over 5 yrs, serum PIIANP and urinary CTX-II were available for 84/135 patients. There were 24 progressors and 60 non-progressors. Overall, over the 5-yr study period average PIIANP and CTX-II levels were higher in progressors compared with non-progressors (P < 0.05 for both, ANOVA). The patients with serum PIIANP in the highest quartile of 5-yr levels of PIIANP had a significantly higher risk of progression than the other patients [relative risk (95% CI): 3.2 (1.1–9.2)]. Increased levels of urinary CTX-II were also associated with a higher risk of progression with a relative risk (95% CI) of 3.4 (1.2–9.4) in patients with 5-yr levels above the median. The risk of progression was highest in patients with 5-yr levels of PIIANP in the highest quartile and/or CTX-II in the two highest quartiles with a relative risk (95% CI) of progression, 11.8 (2.5–54).
Conclusions. The data presented here suggest that progression of knee OA is associated with alterations of systemic levels of biological markers of type II collagen metabolism. The data also suggest that the combined measurement of serum PIIANP and urinary CTX-II may be useful to identify patients with knee OA at increased risk of disease progression.
KEY WORDS: Type II collagen, Synthesis, Degradation, Osteoarthritis, Disease outcome
Submitted 5 May 2006; Accepted 7 November 2006