“An alternative to oral NSAIDs for acute musculoskeletal injuries,” (PURLs, J Fam Pract. 2011;60:147-148) promotes an unreasonable conclusion. The Cochrane review on which it is based found a 50% response rate to topical diclofenac for ankle sprains, compared with a 25% response to placebo. (A response was defined as ≥50% reduction in pain.) The authors of the Cochrane review seem to think this is adequate, and the authors of this PURL apparently agree.
First, they overstate the benefit. If we consider that 1 in 4 patients respond to placebo, we find that only 1 in 4 patients actually have what the authors describe as an adequate response to topical diclofenac. That still means that half the patients I see for ankle sprain could be calling at 11:00 PM to complain about inadequate pain relief.
Second, the Cochrane reviewers did not use an active control group with oral NSAIDs, leaving us to guess whether oral NSAIDs are equally effective, worse, or better than topical agents. The great majority of people I treat for ankle sprains obtain adequate pain relief with oral therapy. Studies have compared topical and oral NSAIDs, but the authors make no mention of these comparisons.
I trust and rely on the Cochrane reviews, but they are not the word of God. This review did not provide useful information. The space would have been better devoted to a topic I can put into practice.
Dean M. Center, MD
Bozeman, MT
I find it difficult to believe that these ivory tower researchers used topical diclofenac as their base. I’ve used topical agents for acute musculoskeletal pain for 40 years, costing one-tenth (or less) of the price of diclofenac. Only a few patients have complained of skin reactions. For more severe cases, capsaicin is a good choice; otherwise, a methyl salicylate product is very effective, at a concentration of 30% or more. Both are available as generics and do not require a prescription.
Robert Migliorino, DO
Lake Preston, SD
The authors respond:
We appreciate the issues raised by the letter writers. Dr. Center notes that there are few head-to-head trials with other therapy options, such as oral NSAIDs or acetaminophen. We agree. This Cochrane review demonstrates another possible option for pain relief for patients who cannot tolerate oral NSAIDs or prefer not to take them. The body of literature comparing topical to oral NSAIDs is small, but we could not find any high-quality evidence to suggest that oral NSAIDs are more effective.
Dr. Center also questions the clinical utility of a medication that must be given to 4 patients in order for 1 to have a 50% reduction in pain (number needed to treat [NNT]=4). The NNT for topical NSAIDs is about the same.1 For acute musculoskeletal injuries, 1 patient in 4 will respond to placebo, 1 in 4 will respond to active topical or oral therapy, and 2 in 4 will fail treatment. Whether these response rates are acceptable is an individual clinical decision to be made with the patient. We believe they are acceptable to most patients.
We thank Dr. Migliorino for bringing to light other topical pain medications. Diclofenac is the only topical NSAID available in the United States, which is why we chose to highlight it. The Cochrane review did not include salicylates because they are no longer classified as topical NSAIDS, and capsaicin was not included as it is not an NSAID. Both may very well offer pain relief.
The purpose of PURLs (Priority Updates from the Research Literature) is to identify and disseminate evidence that should change the practice of family medicine. We believe that this Cochrane review demonstrates that topical NSAIDs are effective options for acute musculoskeletal injuries and that many primary care physicians would be unfamiliar with this option.
Nina V. Rogers, MD
Kate Rowland, MD
Chicago