Chondroitin May Act as Disease Modifier in Knee Osteoarthritis

NEW YORK (Reuters Health) Feb 09 - Long-term use of prescription-grade chondroitins 4 and 6 sulfate (CS) for treatment of knee osteoarthritis reduces pain and slows joint narrowing, investigators report in the February issue of Arthritis and Rheumatism.
The Study on Osteoarthritis Progression Prevention (STOPP) involved 622 patients in Europe and the US, ages 45-80 years, with primary knee osteoarthritis of the medial tibiofemoral compartment. Mean baseline pain scores were 57 mm on a 100-mm visual analog scale.
Patients were randomly assigned to 2 years of daily treatment with an 800-mg sachet of highly purified CS of bovine origin (n = 309) or identical placebo (n = 313). The per-protocol analysis included 206 and 217 patients, respectively. Radiographs of the target knee were obtained using the Lyon Schuss view and assessed by digital image analysis.
Structural effects and pain relief increased with time in the CS group, lead author Dr. Andre Kahan, at Cochin Hospital in Paris, and colleagues report.
The intent-to-treat analysis at 24 months showed a significantly smaller minimum joint space width loss in the CS group (-0.07 mm vs -0.31 mm; median difference 0.14 mm, p < 0.0001). The authors observed a 33% relative risk reduction for joint narrowing.
In addition, the percentage of patients with radiographic progression of less than 0.25 mm was lower in the CS group (28% vs 41% in the control group, p <0.0005).
The decrease in pain scores also favored CS, with significant differences from placebo between months 1 and 9.
The per-protocol analysis showed a median 0.20 mm difference over 24 months in minimum joint space width loss (p < 0.0001), and better global efficacy scores at 6 months (median 50 vs 35, p = 0.03) associated with CS use.
In the per protocol radiographic analysis, the number of patients needed to treat was 5. In the intent-to-treat analysis, the number needed to treat was 8.
Tolerability was deemed good or very good by more than 90% of subjects, with no significant difference between groups in the frequency of adverse events.
The authors note that because the CS used in the STOPP trial is a prescription drug, the results cannot be generalized to chondroitin products sold as dietary supplements.
"The long-term combined structure-modifying and symptom-modifying effects of CS suggest that it could be a disease-modifying agent in patients with knee osteoarthritis," Dr. Kahan and associates conclude.