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.


Review of Coleman, SR et. al. Clinical Efficacy of Noninvasive Cryolipolysis and Its Effects on Peripheral Nerves

May 3, 2009

Aesthetic Plast Surg. 2009 Mar 19

Clinical Efficacy of Noninvasive Cryolipolysis and Its Effects on Peripheral Nerves

Coleman SR, Sachdeva K, Egbert BM, Preciado J, Allison J.

Review copyright 2009

Coleman and colleagues present the first clinical report on the ‘love handles’ of 10 patients using the Zeltiq non-invasive fat reduction device.  The investigators used repeatable data collection methods, and proper data analysis procedures, resulting in a highly credible paper.

During a single patient visit, the Zeltiq treatment was administered to one of two love handles, with two to three applications of the cooling device, so as to sufficiently cover the area to be treated.  The opposite love handle was left untreated and used as the control. Follow up visits for fat thickness measurements were performed at 2 months and 6 months.

Fat thickness reduction (from ultrasound images) was used as an quantitative measure of efficacy, at various follow-up points compared to baseline.  The investigators went to great lengths to ensure measurement accuracy, using a transparency to align ultrasound measurements at the various time points, and collecting up to 12 evenly spaced ultrasound measurements at each location.  Generous amounts of ultrasound coupling gel were used to prevent the ultrasound probe from compressing the dermis and fat.  Overall fat layer thickness reduction was calculated by subtracting the ‘fat thickness change on the control side’ from the ‘fat thickness change on the treated side,’  where the fat thickness change for each patient was the average of the up-to-12 individual measurements.  The authors properly used this internal control, unlike so many papers in this field.

Additionally, efficacy was also measured by photographic assessment of treated versus control area, using standardized photography setup at a series of viewing angles every 22.5 degrees from 0 degrees to 360 degrees.  Three blinded reviewers compared baseline and 4-month post-treatment photos for five subjects for whom four month follow-up was available.  Again the investigators used blinding properly, to produce reliable results.

Transient numbness is a common, non-serious complication of the Zeltiq treatment.  Sensory neurologic assessment of the treated area was performed in nine patients at baseline and weekly post-treatment for 2 months. In one patient, nerve biopsies were collected at 3 weeks and 6 weeks post-treatment, at the treated site and a contralateral control, and evaluated for signs of sensory impairment.

There were no serious adverse events.  One patient had a non-serious adverse event during treatment.  After treating the median area of the love handle, the applicator was applied to the left anterior area.  After several minutes the subject reported pain and the treatment was aborted.  Other than redness that lasted six hours there was no other effect.  This subject did not complete the treatment, so no follow-ups were performed.

Erythema was observed in all 25 treatment locations of 9 patients who completed study. Numbness was reported at 24 of 25 treatment locations, which improved at a 1-week phone follow-up and resolved completely by the 2 month follow-up visit. Three of nine subjects did not complete the 6 month follow-up ultrasound, and two subjects did not complete the 6-month follow-up photographs.

Unlike prior reports of non-invasive body contouring, the authors in this paper present their results as a percent reduction, rather than a centimeter reduction.  AestheticDeviceReview speculates that the authors found a correlation between starting fat thickness and the amount of reduction, and so chose to report a percentage rather than an absolute amount.  In the six patients with six-month data, ultrasound fat thickness reduction was 20.4% +/- 4.9% in the treated side versus control at two months, and 25.5% +/- 9.5% at six months.  All patients had at least 11.5% reduction at 2 months, and 10.7% reduction at 6 months.  These are impressive results for a single treatment,demonstrating that results last for at least six months. 

For the blinded photographic assessment, the blinded reviewers were able to correctly pick the follow-up versus the baseline image 93% of the time.  If there were no treatment effect, we would expect the reviewers to be correct 50% of the time.  Again, these are impressive results, and objectively indicate cosmetic improvement.

For the nine subjects who completed the battery of sensory tests, 3 subjects had no change from baseline during the study on any test, and the other 6 showed steady improvement over six weeks with full resolution at week seven.  Nerve biopsy results on one patient showed completely normal nerves at 6 weeks, suggesting cryolipolysis does not cause any long-term damage.  Given the small number of patients, these results do not completely rule out the possibility of long-term nerve damage in a larger population of patients.  We need to await further results.

Transient hypo-esthesia seems to be a common complication of the Zeltiq technique.  It is not explained why one patient felt pain and could not complete treatment.  Fat thickness measurements were performed in a well controlled manner, and the treatment side was properly analyzed versus controls.  Unusually, fat thickness reductions were reported as a percentage reduction, and centimeter reduction was not reported.  There was no correlation between the fat thickness change and weight change in this group.  Blinded photographic assessment shows that the clinical changes are visible to trained observers.  It is not clear if the clinical changes are evident to patients, especially since the changes take a long time to become visible. Patient satisfaction was not measured, and it is not known if the patients were offered subsequent treatment of the contralateral side.  It is not known why there were so many drop-outs for follow-up; possibilities include the large number of follow-up visits, the long duration between the treatment and the 4 and 6 month follow-up visits, or a lack of subject interest in the result.  Nevertheless, the main results – sustained fat thickness reduction and cosmetic improvement – are credible and compelling.

Review of Boulos PR et. al. In the eye of the beholder–skin rejuvenation using a light-emitting diode photomodulation device

April 12, 2009

Dermatol Surg. 2009 Feb;35(2):229-39.

In the eye of the beholder–skin rejuvenation using a light-emitting diode photomodulation device

Boulos PR, Kelley JM, Falcão MF, Tremblay JF, Davis RB, Hatton MP, Rubin PA

Review copyright 2009

In an unusual article, Boulos and colleagues present compelling evidence that the GentleWaves LED device simply does not work, and that patient satisfaction is simply the result of a placebo effect.

In this study, 36 patients were treated with the GentleWaves device weekly for 8 weeks, as suggested by several other researchers.  Standardized photography was performed pre-treatment, immediately post-treatment, and 1 month post-treatment.  The unblinded investigator also performed clinical assessments at the same time points.

Thirty raters were asked to select the “after” photo from a randomly ordered before/after pair, looking at one of five aspects of the treatment – redness, wrinkles, dark spots, skin roughness, and general appearance.  Unfortunately, the results were not different from chance.

The data were re-evaluated by using a consensus of three raters for each aspect.  Still, the results were no different from chance.

Next, statistical power was increased by using raters’ confidence in their own judgements to weight the data.  In other words, this analysis more highly weighted the decisions that the raters felt sure about, and underweighted the decisions where the raters felt unsure.  Nevertheless, results again were not different from chance.

Finally, the unblinded investigator’s clinical assessments showed that “there was essentially no effect, or if anything, a negative effect.”

Despite the lack of any objective evidence of improvement whatsoever, patients were quite pleased with the results.  The authors conclude that the treatment is a classic placebo, where patients feel better because they believe that the treatment will work, even though it does nothing.  At AestheticDeviceReview, we would like to see more devices subjected to this type of study.