Randomised controlled trials (RCTs) comparing any topical NSAID with placebo or vehicle, of at least 4 weeks' duration, were eligible for inclusion. Studies of topical therapies other than NSAIDs, or of patients using any other therapies alongside topical NSAIDs, except for rescue medication, were excluded. Active treatment in the included studies consisted of topical diclofenac or diclofenac or eltenac gel. The comparator in all but one trial was placebo; one trial used a vehicle control (dimethyl sulphoxide). The duration of treatment varied between studies and lasted between 4 and 12 weeks. Studies of patients with primary knee OA, confirmed by radiology, were eligible for inclusion. Studies of mixed patient populations, of patients with nonarthritic joint pain, or of patients with OA of joints other than the knee, were excluded. Most of the participants included in the treatment groups were women (range: 61 to 82%), and the mean age ranged from 60.8 to 67 years old. The primary end point was pain score. The authors reported that different pain measurement scales were used in the included studies but did not provide further details.
The authors did not report how the papers were selected for the review, or how many reviewers performed the study selection.