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QUESTION: In patients with common paediatric warts, is duct tape occlusion treatment more effective than cryotherapy for improving wart resolution?
Madigan Army Medical Center, Tacoma, Washington, USA.
61 patients (age range 3–22 y) who had common warts. Exclusion criteria included immunodeficiency states; chronic skin diseases (eg, eczema or psoriasis); allergy to adhesive tape; warts located on the face, periungual, perianal, or genital areas; and previous cryotherapy for the same wart. Follow up was 84% (mean age 9 y, 51% girls).
Patients were allocated to duct tape occlusion treatment for a maximum of 2 months or until resolution of the wart (n=30) or cryotherapy every 2–3 weeks for a maximum of 6 treatments or until resolution of the wart (n=31). Patients in the duct tape group received a supply of standard duct tape. The first piece of duct tape, cut as close to the size of the wart as possible, was applied to the wart in the clinic by nursing personnel and left in place for 6 days. After 6 days, the wart was debrided, and the tape left off over night and reapplied the next morning. Patients in the cryotherapy group received a standard application of liquid nitrogen to the wart for 10 seconds.
Main outcome measures
Complete resolution of the wart being studied.
More warts in the duct tape group than in the cryotherapy group had completely resolved at the end of the treatment period (table).
In patients with common paediatric warts, duct tape occlusion treatment was more effective than cryotherapy for improving wart resolution.
Viral warts are common complaints. Although they are painful over a pressure point, the main reason for seeking treatment is cosmetic appearance. In addition to over the counter topical treatments, cryotherapy is available from physicians who widely believe that it is more effective. The trial by Focht et al and the systematic review by Gibbs et al raise a number of methodological issues that have been discussed elsewhere.1–2 Both studies call into question the effectiveness of freezing warts with liquid nitrogen. Should physicians abandon cryotherapy?
In the trial, duct tape was found to be more effective than cryotherapy, but the absolute effectiveness of cryotherapy was difficult to determine because no placebo group was used. In the systematic review, the average placebo cure rates were 30% in the 17 trials that used a placebo group. Surprisingly little is known about the longer term natural history of viral warts. A study by Massing and Epstein of 1000 institutionalised children suggested that over two thirds of warts (single and multiple) disappeared without any form of treatment after 2 years.3 Similar 2 year clearance rates have been reported elsewhere,4 reinforcing the point that “no treatment” must remain a viable option to many patients, or that at least a “no treatment” group should be included in future clinical studies to assess the additional benefit of treatment.
Thirteen years ago, Glover commented in a review of warts that “the knowledge of the disease and its treatments is often inversely proportional to the frequency of the disease”.5 The well done systematic review on local treatments by Gibbs et al confirms that little has changed since Glover threw down the gauntlet. The history of RCTs for viral warts is largely a shambles, characterised by a profusion of small poor quality studies that do not take several important factors into account. These include age of patient, location of the warts on the feet or hands, type of wart, duration of wart and previous treatment, source of participants (from primary or secondary care), as well as factors relating to the intervention such as timing, duration, and frequency of cryotherapy. Long term studies are needed to capture wart recurrences.1 Altman goes on to discuss design options for future RCTs, such as within patient comparisons and the importance of considering individual people and not warts as the unit of analysis.2
In the meantime, as we await better evidence, when faced with someone presenting with a wart, it may be prudent to first consider doing nothing given the high rate of natural resolution of some warts. Then we should try out treatments that are best supported by the available evidence base and those with the least propensity to cause harm, such as topical salicylic acid gels or duct tape. Cryotherapy could be reserved as a third option should these 2 fail.