Pitfalls in facial hair growth assessment with TrichoScan

ARTICLE

Auteur(s) : Dominique Van Neste¹, D Hugh Rushton²

¹Skinterface, 9 rue du Sondart, B-7500 Tournai
²School of Pharmacy & Biomedical Sciences, University of Portsmouth, Portsmouth Hants, PO1 2DT, UK

We would like to share our comments about a paper reporting on facial growth [1] and have detailed those areas of concern and offer the following comments.

In the introduction, the author mentions that unwanted facial hair should be quantified by measuring hair growth rate, density and thickness [1] but in this pharmacodynamic study there is no mention of the growth phase of the hair cycle i.e. anagen, the phase sensitive to eflornithine. Why?

Further, while average facial hair growth rates in hirsute females are similar to or sometimes higher than those of scalp hair (facial hair, range: 0.4-1.2 mm/d [2]; scalp hair: range 0.35-0.42 mm/d [3]), with notably slower grow rates for vellus hair (average 0.06 mm/d [4]). We would firstly ask about the rationale for the use of a 7-day interval between shaving at (d0) and imaging (d7) instead of the 2 or 3 day interval employed for scalp hair growth measurements.

Secondly, we were surprised to see females complaining of excessive facial hair growth with negative hair growth rate values. For example, in figure 7 at least 1 subject at baseline, and 3, 6, and 5 subjects respectively after one, two and four months of repeated application of eflornithine (11.5%; 2 times daily) were reported to have negative values. Positive measurements appear in all figures i.e. 4, 5 and 6, thus the reported negative values cannot be the result of mathematical manipulation. Consequently, the only explanation would be an unidentified error in the measurement system. A further possible measurement error also occurs in figure 7 where the Y-axis scale indicates hair growth rates in mm per day (mm/d); if correct then women with exceptionally fast growing moustaches must have taken part in this trial. In any event we can find no peer-reviewed publication validating the use of the TrichoScan in facial hair growth assessment.

Finally, we were troubled by the apparent self-marketing of a commercial product in a scientific paper. This is wholly inappropriate and should have been identified at peer-review or by the editorial board. We would refer the interested readers, who would like to deepen their reflection on sound scientific publication policies and dogmatic statements about what a technique can appropriately measure, to editorials dealing with such matters [5, 6].

References

2 Hines G, Moran C, Huerta R, Folgman K, Azziz R. Facial and abdominal hair growth in hirsutism: A computerized evaluation. J Am Acad Dermatol 2001; 45: 846-50.

3 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.

4 Blume U, Ferracin I, Verschoore M, Czernielewski JM, Schaefer H. Physiology of the vellus hair follicle: hair growth and sebum excretion. Br J Dermatol 1991; 124: 21-8.

5 Goldsmith LA, Hall RP, Qaqish B. Errors in the lab and in publications. J Invest Dermatol 2006; 126: 1195-6.

6 Van Neste D. Placebo pills, lotions or potions and the natural progression of patterned hair loss in males: another step away from “trichoquakery”? Eur J Dermatol 2008; 18: 373-5.