COPPER-SALICYLATE GEL FOR PAIN RELIEF IN OSTEOARTHRITIS - A RANDOMIZED CONTROLLED TRIAL

Objective: To assess the efficacy and safety of a copper-salicylate ge l in osteoarthritis of the hip and knee. Design: Randomised, double-bl ind, placebo-controlled study. Setting: Rheumatology Clinic of St Vinc ent's Hospital, Sydney, New South Wales (a tertiary referral hospital) , June 1993 to October 1994. Patients: 116 patients with pain associat ed with osteoarthritis of the hip and/or knee (diagnosed by criteria o f the European League against Rheumatism), drawn from patients attendi ng the Clinic or self-referred after newspaper advertisements. Interve ntion: Copper-salicylate or placebo gel (1.5 g) applied twice daily to the forearm for four weeks. Outcome measures: Self-assessment of pain before the trial and after two and four weeks of treatment; patient a nd investigator assessments of efficacy; additional analgesia required ; adverse reactions; and withdrawal rates. Results: Pain scores at res t and on movement decreased in both the copper-salicylate and placebo groups by 13%-20%. There was no significant difference between the two groups for decrease in pain score, patient and investigator efficacy ratings, number of patients requiring paracetamol for extra analgesia (active, 77%; placebo, 71%) and average dose of paracetamol (active, 5 55 mg/day; placebo, 600 mg/day). Significantly more patients in the co pper-salicylate group reported adverse reactions (83% versus 52% of th e placebo group), most commonly skin reactions, and withdrew from the trial because of these reactions (17% versus 1.7% of the placebo group ). Conclusion: Copper-salicylate gel applied to the forearm was no bet ter than placebo gel as pain relief for patients with osteoarthritis o f the hip or knee, but produced significantly more skin rashes.