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Dear Editor,

We would like to answer the points made by Dr. Bertolotti and Dr. Derancourt in their letter to the editor regarding the paper “A Multicentre, randomised clinical trial to compare a topical Nitrizinc® complex solution versus cryotherapy for the treatment of anogenital warts,” by Pontini et al.

First of all, we thank the authors for their observations, which mainly reflect the difficulties in planning studies on the treatment of anogenital warts.

We will try to respond to each point that was raised:

  • Nitrizinc complex solution was applied following the manufacturer’s instructions. It is true that certain practical skills are needed to obtain the best results; these are difficult to describe. The same can be said about the use of cryoprobe. The procedure described by Bertolotti is what is usually done; we decided on a shorter interval (10 instead of 14 days) for practical issues, although we understand that this can represent a bias in comparing randomized clinical trials (RCTs).

  • Blinding is a serious issue in planning RCTs in the field of anogenital warts. The suggestions made are quite complicated to perform in practice. We tried to keep our trial as simple as possible and also to maintain the context of daily clinical practice. To collect objective results, we decided that the investigator who evaluated the severity and response to treatment should be blind to the treatment applied, thereby reducing potential bias in the interpretation of results. We decided to treat all the patients for ethical reasons, due to the risk of partner contamination. It is not always easy to take photographs of the genital areas, and it may be disturbing for some patients.

  • The majority of recurrences are reported to occur within the first 3 months. Certainly a longer evaluation period of 6–12 months would be interesting; however, in our experience, the number of patients not coming back after 6–12 months following treatment could be very high, preventing the collection of strong enough data for accurate interpretation. We therefore decided to follow up the patients for a period of 3 months, which we believed would give good enough data.

Finally, we want to thank again Dr. Bertolotti and colleague for their observations, and we completely agree with their final statement.