Cartilage turnover, but not novel synovial collagen marker, is associated with joint damage progression in osteoarthritis patients

Objective To investigate the relative contribution of cartilage and synovial turnover to predict progression in patients with knee or hip osteoarthritis (OA). Methods 449 patients with symptomatic knee or hip OA (mean age: 62 yr, 62% women) with a Kellgren-Lawrence (KL) score > =2 from the prospective KHOALA cohort study were investigated. Progression was defined as a one-point increase in the KL scores from knee or hip radiographs and/or a joint replacement during 5 years follow-up. The association of baseline urinary CTX-II and serum Col 3–4, biochemical markers of cartilage and synovial turnover, respectively, with progression was assessed by multivariable discrete-time survival models. Results Increased baseline CTX-II levels were associated with an increased risk of knee and/or hip OA progression, patients with levels in the fourth quartile having an odds-ratio (OR; 95%CI) of 2.57 (1.57–4.18) compared with subjects with levels in first quartile, after adjustment for demographical and OA clinical variables and KL scores. When analyses were restricted to patients with knee or hip OA progression only, similar findings were obtained with corresponding ORs (95% CI) of 2.36 (1.32–4.21) and 3.39 (1.42–8.11), respectively. There was no significant association of baseline Col 3–4 and the risk of knee or hip progression. Conclusions Increased urinary CTX-II, but not Col 3–4, is independently associated with a higher risk of structural progression in patients with knee or hip OA. Cartilage turnover may play a more important role than synovial activity as assessed with Col 3–4 to mediate joint damage in established OA. Clinical Trial registration ClinicalTrials.gov; NCT00481338