Review of Bousquet-Rouaud, High-frequency ultrasound evaluation of cellulite treated with the 1064 nm Nd:YAG laser

March 8, 2009

http://www.ncbi.nlm.nih.gov/pubmed/19214861

J Cosmet Laser Ther. 2009 Mar;11(1):34-44

High-frequency ultrasound evaluation of cellulite treated with the 1064 nm Nd:YAG laser.

Bousquet-Rouaud R, Bazan M, Chaintreuil J, Echague AV.

Dermatological Laser Unit, Millenium Clinic, Montpellier, France.

 

This article presents the first evaluation of the use of a high-power pulsed Nd:YAG laser for the treatment of cellulite.  Three of the four authors are employees of Candela Corporation, the maker of the laser.

The study at first appears to be well-designed.  Quantitative endpoints of dermis thickness and ultrasound density were chosen, and preliminary studies were performed to show that measurement methods were not subject to intra-observer or inter-observer error.  Twelve patients were treated, with one thigh randomized to treatment and the other randomized to control.  In addition to pre-treatment ultrasound measurements, follow-up measurements were performed at 1 month and 3 months after the final treatment of the series of three treatments.  Adjunctive photographs were taken before each treatment, and presumably at the follow-up visits.  The example photograph appears to be of high quality.  The treatments were appropriately standardized to minimize the impact of dosage variation on outcome.  Likewise, the patient population appears to be reasonably homogenous in terms of age, body mass index, and pre-treatment evaluation of cellulite severity, to minimize the impact of patient variation on outcome variation.

Given the apparent care taken in the study design, the analysis was extremely disappointing.  The analysis presents only the variation in ultrasound measurements of the treated thigh, and completely ignores the control thigh.  The authors claim that the mean dermal thickness of treated thighs decreases from the beginning to the end of the study, but this is a flawed claim.  Because they do not present data on the control thigh, we cannot know if this result stems from a treatment effect, or from a natural variation in the patient population over time.  For all we know, the dermal thickness of the control thigh improved more than the treated leg.  This is the whole point of having a control thigh.  No other control variables, such as BMI or weight, were presented.

Further, the authors include the raw data for the dermal thickness measurements in all 12 patients, but offer no explanation why some patients have increased thickness at 1 month follow-up which then decreases at 3 months, while other patients show decreased thickness at 1 month with subsequent increases at 3 months.  Presumably, the treatment effect would go in generally the same direction in this homogeneous group that recieved the same treatment regime.  This variation adds to the concern that something else was going on with these patients during the study that might effect dermal thickness.  The same comments apply to the raw data on dermal echogenicity.

The exclusion of measurements of the control thigh from the analysis renders any conclusions moot.  The authors further present patient satisfaction data.  This type of data is notoriously challenging to interpret, as patients often feel satisfied that they are taking steps towards treating a condition. In this case, on average the patients reported being somewhat satisfied, and no patients reported being very satisfied.  Readers of the article should not be satisfied at all.

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