Glucosamine sulphate has been shown in a large double-blind, placebo-controlled clinical trial to prevent structural damage and improve clinical symptoms of osteoarthritis (OA). We investigated whether early response in a newly developed biochemical marker of collagen type II degradation (CTX-II, CartiLaps ELISA) could reflect the long-term preservation of hyaline cartilage.
Study subjects comprised 212 knee OA patients participating in a clinical trial of the effects of glucosamine sulphate. Disease symptoms were assessed quarterly by WOMAC scoring and X-ray analysis was performed at baseline and after 3 years. Urine samples were obtained at baseline and after 1, 2 and 3 years for measurement in the CartiLaps assay. The measurements were corrected for creatinine.
At baseline the patients had an average concentration of urinary CTX-II of 222.4 +/- 159.5 ng/mmol creatinine. This was significantly above the CTX-II levels measured in urine samples from 415 healthy controls (169.1 +/- 92.3 ng/mmol, p < 0.0001). There was no significant difference in the CTX-II response in the placebo group and the glucosamine treated group. However, those with high cartilage turnover presented a significant decrease in CTX-II after 12-month glucosamine treatment. Thus, three group with CTX II concentrations above normal average + 1SD decreased 15.5% after 12-month therapy. The 12 months change in CTX-II in OA patients with elevated CTX-II at baseline correlated with the change in average joint space width observed after 36 months (R = 0.43, p < 0.05). Increased baseline levels of CTX-II were associated with a worsening of the WOMAC index (p < 0.01).
The data indicate that measurement of urinary collagen type II C-telopeptide fragments enables the identification of OA patients with high cartilage turnover who at the same time are most responsive to therapy with structure modifying drugs.