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Plantar wart therapy smackdown: Cryotherapy vs. salicylic acid


 

EXPERT OPINION FROM SDEF HAWAII DERMATOLOGY SEMINAR

MAUI, HAWAII – Are British academic podiatrists out to bring down dermatology?

That possibility was raised, tongue firmly in cheek, by Dr. Andrew C. Krakowski at the Hawaii Dermatology Seminar sponsored by Global Academy for Medical Education/Skin Disease Education Foundation in light of the results of the EVerT (Effective Verruca Treatments) trial.

EVerT was a multicenter clinical trial in which university podiatrists in England, Scotland, and Ireland randomized 240 patients with plantar warts to one of two venerable treatments: cryotherapy or salicylic acid.

Dr. Andrew Krakowski of San Diego

The investigators declared salicylic acid the winner – or as they put it in more rococo British fashion, "cryotherapy is the dominated alternative" – on the grounds that although the two treatments showed equal efficacy, cryotherapy cost an average of 101 British pounds (U.S.$153) more per patient over the course of the 12-week study.

"Will dermatologists be out of business? Cryotherapy is sort of our livelihood. It’s something we all do every day," noted Dr. Krakowski, a pediatric dermatologist at the University of California, San Diego.

So, is this the end of the line for a bread-and-butter dermatologic procedure? Not bloody likely. While the EVerT trial is sure to draw the attention of U.K. health policy makers – it was, after all, funded by the U.K. National Institute for Health Research Health Technology Assessment Programme – the study was a bit of a dog’s breakfast, with numerous methodologic flaws that undermined the investigators’ conclusions, in Dr. Krakowski’s view.

Patients in the cryotherapy arm received up to four liquid-nitrogen treatments 2-3 weeks apart. Those assigned to salicylic acid were instructed to file and pare the wart and apply 50% salicylic acid at home daily for up to 8 weeks. The primary endpoint – complete plantar wart clearance at 12 weeks by photographic assessment – was attained in 14.3% of the salicylic acid group and 13.6% of cryotherapy-treated patients, a nonsignificant difference.

Fourteen adverse events, none serious, were noted in each study arm. Self-reported clearance of warts at 6 months was similar in both groups as well: 31% in the salicylic acid group and 34% with cryotherapy (BMJ 2011;342:d3271).

A subsequent comprehensive cost-effectiveness analysis tabulated the mean total cost of cryotherapy through 12 weeks at 150.39 pounds ($228), compared with 49.22 pounds ($75) for treatment with salicylic acid (J. Foot Ankle Res. 2012;5:28).

From the perspective of a dermatologist, however, there are problems aplenty with EVerT, according to Dr. Krakowski.

For one, the cryotherapy was done mainly by nurses; dermatologists – the acknowledged experts in cryotherapy – weren’t part of the study. The technique wasn’t standardized, and it’s not clear that all cryotherapy applications followed the accepted 10-second freeze/create-an-iceball approach. In addition, the notion that patients would be compliant with a home regimen entailing daily wart filing and application of salicylic acid requires a considerable leap of faith. Moreover, basing outcome analysis on evaluation of photographs was considerably less convincing than if wart clearance was assessed by direct patient examination by a dermatologist using a dermoscope, which can show definitively whether a wart is completely gone.

Last, the investigators downplayed the importance of their patient satisfaction data: 62% of patients whose plantar warts were treated using liquid nitrogen pronounced themselves "happy with their treatment," compared with just 41% of those in the salicylic acid group, Dr. Krakowski noted.

He added that his own "best and most used" treatment for cutaneous warts, including plantar warts, combines both elements of the EVerT trial: paring with duct tape with application of salicylic acid at home along with in-office cryotherapy.

"I freeze it, then in the next 2 days there may or may not be some home therapy that goes on, although that’s what I try to push. Then I see the patients back in a month and freeze the wart again," the dermatologist explained.

One of his favorite techniques is to utilize a hemostat or tweezers to tackle warts in challenging locations.

"The thing I do the most for any wart that’s tricky is I’ll grab an Adson forceps with teeth and freeze it – just drop it into a Styrofoam cup and put in liquid nitrogen to make the tip cold – then I’ll pick up the forceps very carefully, sometimes using gauze to protect my fingers, and I’ll either grab the wart with the forceps or just touch it. You can be very careful in that way such that the surrounding skin isn’t even affected," according to Dr. Krakowski.

SDEF and this news organization are owned by the same parent company.

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