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Am Fam Physician. 2003;68(9):1714-1717

to the editor: The recent article, “Molluscum Contagiosum and Warts,”1 is a praiseworthy attempt to update family physicians on the current treatment options for this commonly encountered problem. However, this paper does not guide physicians on which treatment to choose based on good evidence.

It should be made clear that the methodologic quality of research on various local treatments is mediocre at best. According to the updated systematic review2,3 on local treatments for cutaneous warts in healthy people, there is only good evidence for the therapeutic efficacy and safety of simple topical salicylic acid. Little evidence exists for the efficacy of the other choices of treatment that were mentioned in the article.1 We, as physicians, have no convincing evidence that cryotherapy is any more effective than simple topical treatments.

in reply: Dr. Chow's comments astutely refer physicians to availing themselves to the best possible evidence in the care of our patients. First, Dr. Chow requests guidance as to which treatments to choose based on good evidence. Dr. Chow has referred to the same Cochrane Review1 that Dr. Hutchinson and I refer to in our article,2 which reviews the most appropriate studies to offer assistance in the treatment approach to warts. In addition to referencing that work, our article presents several small studies that explore other treatment options that are prevalent in clinical practice, with reference to the nature of the study, its size, and its outcome. The accompanying table summarizes the estimated treatment success rates based on the information presented in the Cochrane review,1 in our article,2 and in a recent article about using duct tape to treat warts.3

TreatmentEfficacy (%)
None/placebo30 (range: 0 to 70)
Topical salicylic acid75
Cryotherapy30 to 75*
Cimetidine (in children)46 to 75 †
Cimetidine with levamisole86
Candida or mumps injection74
Duct tape853

Two of Dr. Chow's statements, nearly verbatim from the Cochrane review,1 are best interpreted together. (1) “There is only good evidence for the therapeutic efficacy and safety of simple topical salicylic acid,” and (2) “no convincing evidence that cryotherapy is any more effective than simple topical treatments.” Cryotherapy is not more effective, but, if it is equally effective as two of the allowed studies in the Cochrane review1 indicate, then it should be an acceptable treatment, because many patients prefer a one-time treatment to weeks or months of daily applications.

The Cochrane review1 included only randomized controlled trials and did not include data from most of the large trials involving cryotherapy, because those trials primarily compared various methods of cryotherapy. It is my understanding that many trials are appropriate studies comparing variations of treatments without imposing a placebo arm, just as we would hope in chemotherapy trials testing new versus established therapies or in trials comparing aspirin and coumadin (Warfarin) for clotting disorders. An analysis of the large trials that compare various forms of cryotherapy with the estimated spontaneous resolution rate of 30 percent from the Cochrane analysis1 might yield useful information.

Perfect data are not available but based on the best available evidence, cryotherapy appears to be approximately 60 percent effective in the treatment of warts and topical salicylates are approximately 75 percent effective. Data from population studies and control arms of studies show spontaneous resolution to be approximately 30 percent. Physicians will make the decision with their patients as to which treatment or nontreatment will best suit the individual, based on tolerance of the time and work involved in the treatment, and the side effects and efficacy of the treatment.

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This series is coordinated by Kenny Lin, MD, MPH, deputy editor.

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