Response to: D Van Neste and D. Hugh Rushton. Eur J Dermatol 2009; 19 (6): (this issue)

ARTICLE

Auteur(s) : Rolf Hoffmann

Kaiser-Joseph-Str. 262, D-79098 Freiburg

In the article [1] published in the EJD, I reported on the effect of eflornithine 11.5% cream in women complaining about unwanted facial hair. Hirsutism is characterized by increased hair growth rates and increased hair shaft diameters. Thus, investigating changes of hair growth cycle phases is not the topic of this article. The therapeutic interest of using topical eflornithine for the treatment of facial hirsutism is to reduce hair growth activity, especially hair growth rate. The ornithindecarboxylase (ODC) which is blocked by eflornithine is mainly present and active during the growing phase of the hair cycle [2]. Thus eflornithine can only inhibit and influence actively growing hair. The aim of the study was therefore the analysis of the clinically visible hairs, their status of growth activity and, as a final endpoint, the cumulative hair length. The latter is a combined value of the length of all hairs in the test field. On the upper lip it makes no practical difference whether measurements are taken at 3 days or 7 days when calculating average daily growth rates. However, in daily practice patients are more likely to return to a clinic on a weekly basis rather than twice within one week.

In addition, with this technique, in contrast to the method used by Dr. Van Neste, hairs are shaved to the skin surface with no hair left on the surface. If you shave to the skin surface, it is technically very possible to measure precisely after 7 days and to measure the lengths of all regrown hairs.

Dr. Van Neste claims that hair length has no published validation data. This is incorrect and Dr. Van Neste omitted to check the currently published literature. The GCP-validation of the 3.0 TrichoScan Research edition used for the study analysis was recently published in the Eur J Dermatol [3]. In this trial, hair length was also validated. He is, however, correct in saying that there can be no negative growth. I looked at the clinical summary report of this trial again, and attached is figure 1, which is part of the summary report.

There was an error in labelling of the y-axis while re-editing the images for publication in the EJD. I sincerely apologise for this mistake which is now corrected. Nevertheless, this mistake has no impact on the data and curves in the image. With the correct y-axis the growth rates are also corrected.

Dr. Van Neste regards the published study as an apparent self-marketing of a commercial product (TrichoScan). I read this with surprise as I wonder how a study on the efficacy of a drug can be published without mentioning the analytical tools used for the measurements of efficacy? In addition, I wonder why Dr. Van Neste cites his own service of contrast-enhanced phototrichogram here and in his publications [4], which is used in clinical trials and is offered in a commercial setting by Dr. Van Neste, but complains about perceived self-marketing by others?

References

2 Nancarrow MJ, Nesci A, Hynd PI, Powell BC. Dynamic expression of ornithine decarboxylase in hair growth. Mech Dev 1999; 84: 161-4.

3 Gassmueller J, Rowold E, Fraser T, Hughes-Formella B. Validation of TrichoScan ^® technology as a fully-automated tool for evaluation of hair growth parameters. Eur J Dermatol 2009; 19: 224-31.

4 Van Neste D. Female patients complaining about hair loss: documentation of defective scalp hair dynamics with contrast-enhanced phototrichogram. Skin Res Technol 2006; 12: 83-8.