A 5-year randomized controlled, double-blind study of glycosaminoglycan polysulphuric acid complex (Rumalon) as a structure modifying therapy in osteoarthritis of the hip and knee.

Objective: To determine the structure (disease) modifying effect of a glycosaminoglycan polypeptide association complex (GP-C; Rumalon) in patients with knee and hip osteoarthritis (OA).

Methods: Double-blind, randomized, placebo-controlled five-year study. Primary assessment criterion was change in radiographic joint space width between baseline and follow-up at 5 years. Secondary outcome criteria included Lequesne algofunctional index (LAI), pain on passive motion and consumption of non-steroidal antiinflammatory drugs (NSAIDs). The patients received 10 courses of injections of placebo or GP-C 2 ml intramuscularly in 5 years (two courses each year). Each course included 15 injections administered twice weekly.

Results: There were 277 patients with knee OA and 117 patients with hip OA. Control and GP-C treated groups were comparable as to sex, age, duration of disease, body weight, X-ray stage and value of LAI at the baseline. Knee joint space at 5 years decreased 0.37+/-0.08 (mean+/-standard deviation) mm for GP-C and 0.42+/-0.08 mm for placebo groups (P=0.68). Hip joint space at 5 years decreased 0.21+/-0.08 mm for GP-C and 0.22+/-0.08 mm for placebo groups (P=0.53). In a subset of patients with hip OA, Kellgren-Lawrence> or =2 and JSW> or =1 mm, there was a trend in favor of GPC for lower joint space narrowing in 5 years (P=0.11). In addition, there were no statistical differences between the treatment groups in LAI, pain on passive motion and consumption of NSAIDs. Side-effects after GP-C (14.5%) were rare, mild and not more frequent than in the placebo group (15%).

Conclusion: We were not able to demonstrate a structure modifying effect of GP-C in OA of the hip or knee. Radiographic progression of OA in both knee and hip OA was lower than expected in both study groups.