Data from two randomised, double-blind, placebo-controlled studies were considered in order to investigate the efficacy and safety of a bio-adhesive plaster for topical administration containing diclofenac epolamine (DHEP) in patients with symptomatic knee osteoarthritis (OA).
Patients with radiologically confirmed symptomatic knee OA were included. The 14-day treatment consisted of two daily applications of either DHEP or placebo plaster. The algofunctional Lequesne index and pain intensity, measured by means of the Huskisson's visual analogue scale (VAS), were considered as main efficacy parameters. The main analysis of the pooled data was by intention-to-treat.
Of the 258 patients included, 235 completed the study. At the end of the study, the mean decrease in the Lequesne index was 35% in the DHEP group and 15% in the placebo group (p < 0.0001). The mean decrease in pain intensity was 59.5% in the DHEP group and 29.9% in the placebo group. No interaction resulted between treatment and study effects (p > or = 0.2 whatever the test). The non-parametric Hodges-Lehmann estimator of the treatment effect resulted in a reduction of 21.9% for the Lequesne index and of 30.0% in pain intensity. The number needed to treat (NNT) for at least a 50% reduction of pain was 3.0 and the effect size for pain was 0.75.
Topical application of DHEP plaster was shown to be an efficacious and safe short-term treatment for symptomatic knee OA, reducing pain and increasing physical function and may be similar in efficacy to oral non-steroidal anti-inflammatory drugs (as indicated by relative benefit data and NNT value).