Commentary on: Derry S, Moore RA, Rabbie R. Topical NSAIDs for chronic musculoskeletal pain in adults. Cochrane Database Syst Rev 2012;9:CD007400. Context Topical non-steroidal anti-inflammatory drugs (NSAIDS) are readily available from chemists and supermarkets worldwide and are commonly used in the treatment of a number of painful conditions. Their overall efficacy in the long term, particularly in relation to chronic painful conditions such as osteoarthritis, has not been fully established.

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... ethods Derry and colleagues have conducted a thorough and comprehensive review of the area including data from The Cochrane Library, MEDLINE, EMBASE and www. clinicaltrials.gov, as well as their in-house clinical trials registers from 2004 to June 2012. The selection criteria were clearly defined and the methodological quality of each study was appropriately assessed using the Oxford Quality Scale. The studies consisted of randomised double blind studies lasting ≥2 weeks comparing topical NSAID with placebo or an active comparator in ongoing chronic painful conditions. All topical formulations were scrutinised including creams, gels, patches and solutions. The primary outcome of the review was 'clinical success', defined as a 50% reduction in pain, or equivalent measure such as a 'very good' or 'excellent' global assessment of treatment, or 'none' or 'slight' pain on rest or movement, measured on a categorical scale. Secondary outcomes included the number of participants with adverse events, both local and systemic, with particular emphasis on serious gastrointestinal (GI) complications and treatment withdrawals. Findings Results from 7688 participants in 34 studies from 32 publications were analysed and of these, 23 studies directly compared a topical NSAID formulation with placebo. Topical NSAIDS were found to be significantly better than placebo at reducing pain in knee and hand osteoarthritis, but not in other painful conditions. The strongest data was for topical diclofenac-in osteoarthritis of the knee and hand the number needed to treat (NNT) for at least 50% pain relief over 8-12 weeks was 6.4 (4.6-10) for NSAID solution and 11 (7.7-17) for NSAID gel. Analysis of all the studies comparing topical with oral NSAID revealed that the proportion of patients experiencing successful treatment with a topical NSAID was 55% (479/877, range 40-66%) compared with 54% with oral NSAIDS (462/858, range 34-70%) indicating no difference in efficacy. An increase in local adverse events was seen with topical NSAIDs most commonly mild skin reactions such as dry skin, erythema and pruritis. There was no increase in serious adverse events compared with control.