Letter to the Editor. Cimetidine as a First-Line Therapy for Pedal Verruca

To the Editor:

I recently read the article by Barry R. Mullen, DPM, John V. Guiliana, DPM, MS, and Fawaz Nesheiwat, DPM, published in the May/June 2005 issue of the Journal (“Cimetidine as a First-Line Therapy for Pedal Verruca: Eight-Year Retrospective Analysis”). The authors offer their anecdotal experience in treating verruca with cimetidine. In their conclusion, they suggest that cimetidine is a safe, successful therapeutic option for treating verruca.

In their discussion section, they reference two randomized controlled trials published in the late 1990s[1,2] that found no therapeutic advantage in using cimetidine to treat verruca when compared with treatment with a placebo. Randomized controlled trials are the gold standard when determining therapeutic effectiveness; unless they contain a fatal flaw or have failed to detect a clinically important effect owing to the number of patients enrolled, their results should be considered definitive.

Case series are useful for many things, eg, to report rare conditions or adverse effects of therapeutic options, or to postulate a new hypothesis that requires more rigorous testing. However, these types of studies should not form the basis of decisions regarding therapeutic interventions if more valid level 1 evidence (randomized controlled studies) exists; case series lack a control and therefore cannot be statistically validated. Because the data collected in this type of study are uncontrolled and unsystematic, the results of the study cannot be generalized to the larger population.

My conclusion after reading the article is different from that of the authors. My conclusion is that cimetidine is an expensive placebo that should not be used in the treatment of verruca.

If the earlier randomized controlled trials were not definitive, then a repeat of their studies would be warranted to correct their methodologic errors. Publication of a series of cases on the subject serves no purpose but to confuse the issue.