Forty placebo-controlled trials of topical NSAIDs were found. Dichotomous pain outcomes were available from 1,747 patients on active treatment and 1,492 on placebo. An additional 24 trials (4,171 patients) compared different topical NSAIDs, formulations, or routes of drug administration. Topical and oral NSAIDs were compared in 3 studies, one of which also had a placebo control.
Acute conditions (soft tissue trauma, strains, and sprains).
The pooled relative benefit for all 37 placebo-controlled comparisons was 1.7 (95% CI: 1.5, 1.9) and the number-needed-to-treat (NNT) was 3.9 (95% CI: 3.4, 4.4). The same results were produced when pooling the data from only those trials with a quality score of at least 3. The sensitivity analysis based on treatment group size showed that trials with fewer than 40 treated patients produced a significantly lower (better) NNT (2.6, 95% CI: 2.3, 3.1) than either larger trials or all trials. Larger trials with 40 to 80 treated patients produced higher (worse) estimates for the NNT (5.0, 95% CI: 3.7, 7.4) than all trials together, whilst the largest trials (more than 80 treated patients) produced an intermediate NNT (4.6, 95% CI: 3.7, 5.9). For the sensitivity analysis based on the drug (at least 3 trials), ketoprofen, felbinac, ibuprofen and piroxicam showed significant efficacy; the NNT values were 2.6, 3.0, 3.5 and 4.2, respectively. Benzydamine and indomethacin were no different from the placebo.
Chronic conditions (osteoarthritis, tendinitis).
The pooled relative benefit for all 12 comparisons was 2.0 (95% CI: 1.5, 2.7) and the NNT was 3.1 (95% CI: 2.7, 3.8). The sensitivity analyses based on quality score or treatment group size produced no significant change in these estimates; only one trial had a treatment group size of more than 80 patients, and the NNT for this trial was similar to that of the pooled estimate for all trials of more than 40 treated patients. No single topical NSAID was tested in as many as 3 placebo-controlled studies; combined estimates could not, therefore, be calculated for any single drug.
Comparison with oral NSAIDs.
Five studies compared topical with oral NSAIDs; 3 studies in acute conditions and 2 in chronic conditions. None showed significant benefit of oral over topical preparations.