Review of Alster TS et. al. Effect of a novel low-energy pulsed-light device for home-use hair removal

June 2, 2009

Dermatol Surg. 2009 Mar;35(3):483-9.

Effect of a novel low-energy pulsed-light device for home-use hair removal

Alster TS, Tanzi EL.

Review copyright 2009

This appears to be the first clinical study of the Silk’n home use intense pulsed light for hair removal.  The authors call this “the beginning of a major trend in laser dermatology.”  Given the nicely performed study, and promising results presented, they may be right.

In this study, hair removal was evaluated in one or more treatment areas of twenty women, while matched control areas were left untreated.  The subjects generally had lighter skin and darker hair, and treated areas included underarms, forearms, legs, and bikini lines.  Hair counts were performed in treatment areas and control areas, using a reliable method of manual hair counts (average of 3 manual counts in a 2cm2 or 3cm2 template).  Follow-up measurements were performed at 3 and 6 months, which is generally accepted as the appropriate time frame to assess permanent hair reduction.

The results were quite impressive – virtually no change in hair counts of the control sites at any time, but significant reductions in hair counts (36% to 53% depending on body location) at six months.

While small, this study was appropriately powered and appropriately controlled, and used objective, quantitative outcome measures.  While it would have been nice if the study included multiple sites to eliminate the potential for site bias, a single site study is reasonable for the early stage of clinical work and small size of the study.  (According to a company press release in March 2008, more than 150 patients were treated at 4 total centers, where the results of this first study were successfully replicated.  AestheticDeviceReview hopes these results are published soon.)

A curious point of this study is the 2-week intervals in the series of 3 treatments in the study.  Typically, laser hair removal is performed with at least 4-week intervals between treatments, to maximize the amount of hair follicles in the anagen phase, which is thought to provide the best results.  Perhaps, in addition to their novel device, this novel application of bi-weekly treatments contributes to the results.  Further study is needed here.

The study’s author, Dr. Alster, purchased stock options in the company subsequent to the study.  Given these results, and the reported results from the expanded data set, we can expect these options to become quite valuable.