The dietary supplement chondroitin sulfate significantly reduced the progression of joint space narrowing among patients with knee osteoarthritis in a multicenter, prospective, double-blind study presented in a late-breaking abstract session at the annual meeting of the American College of Rheumatology.
This radiologic finding represents a structure-modifying effect in the clinical progression of the disease, according to the Institute Biochimique SA (Pambio-Noranco, Switzerland), the manufacturer of Chondrosulf, the chondroitin formulation used in the study.
The two-year Study on Osteoarthritis Progression Prevention (STOPP) included 622 patients with mild to moderate ostheoarhritis from 40 centers in Europe and the United States, randomized to receive oral chondroitin sulfate 800mg/day or placebo. Rescue acetaminophen and non-steroidal anti-inflammatory drugs were permitted. All had tibiofemoral knee osteoarthritis evaluated for pain on a visual analog scale and radiologically on digital x-rays using a high-performance Lyon schuss slightly modified semiflexed view.
The minimal level of pain for inclusion was 33 mm for the past three months, and the minimum joint space was greater than one mm at the narrowest point.
Patients were 45-80 years old, with a mean body mass index of 29 kg/m2, and were less overweight than patients in some similar trials such as the National Institutes of Health’s Glucosamine/Chondroitin Arthritis Intervention Trial. If both knees were affected, the more severely affected knee was chosen as the index joint.
There were 206 completers in both groups. In an intention-to-treat analysis of the primary outcome measure-joint space narrowing at the medial compartment of the knee over 24 months — a significantly greater mean joint space narrowing of 0.24 mm was seen among patients receiving placebo, compared with 0.10 mm among those receiving chondroitin.
The change in joint space was linear among patients receiving placebo, around 0.1 mm/year. For patients receiving chondroitin, “the final difference was 55 percent prevention in joint space narrowing, which was statistically significant at the end of the second year. Significant differences were seen in VAS pain scores and Western Ontario and McMaster Universities osteoarthritis index scores. The chondroitin group also used 20 percent fewer NSAIDs, compared with the placebo group.