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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Review of Faurschou A, Pulsed dye laser vs. intense pulsed light for port-wine stains

February 22, 2009

http://www.ncbi.nlm.nih.gov/pubmed/19120324

Br J Dermatol. 2008 Dec 11.

 

Pulsed dye laser vs. intense pulsed light for port-wine stains: a randomized side-by-side trial with blinded response evaluation.

 

Faurschou A, Togsverd-Bo K, Zachariae C, Hædersdal M.

 

Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, DK-2400 Copenhagen NV, Denmark.

 

This study is from the same Denmark group that recently compared the pulse dye laser (LPDL) to the intense pulsed light (IPL) for the treatment of photoaging.  In this study, Annesofie Faurschou reports another head-to-head study comparing these two device types, this time for the treatment of portwine stains.  The study was supported by the laser manufacturer and the local sales agent for the IPL, but neither sponsor participated in the conduct or analysis of the study.  In particular, this study compared the Candela VBeam Perfecta (long pulse 595nm dye laser) with the Palomar StarLux IPL with a Lux G handpiece.

The study was adequately, though not optimally, designed to demonstrate the differences with each type of treatment.  First, each study participant received one split-lesion treatment, with the one half of the lesion randomized to each device type, which properly controls for non-study effects (e.g. additional sun exposure).  The use of a split-face design also appropriately controls for patient variability.  However, the use of a series of multiple treatments would have magnified any possible outcome differences, and would better reflect clinical practice.   Second, one evaluation was performed photographically by a blinded assessor.  Blinding appropriately prevents bias, but the introduction of photographic artifact may obscure outcome differences.  Third, a second evaluation was performed with a skin reflectance meter, also performed by a assessor blinded to device-types used on each half.  Blinding appropriately prevents bias, but this meter has been validated for the use of evaluating erythema and pigmentation rather than portwine stains.

In this study, while both devices achieved measurable PWS lightening and no adverse events were found, the pulsed dye laser showed superior efficacy, both by blinded photographic evaluation and by blinded skin photometer.  The difference in lightening was both statistically and clinically significant (i.e. the difference in lightening was visually apparent to the blinded reviewer and the patient), even though only one treatment was performed.  As far as patient preference, 18 of 20 patients preferred to have subsequent treatments with the LPDL, while 2 preferred the IPL.

The superior results of the pulse dye laser may not be considered definitive based solely on this study, as there was no-pre-defined study hypothesis to be proven.  However, the authors refer to several other studies to underline their proposal that the LPDL be considered the first choice modality for PWS treatment, with the IPL reserved for poor-LPDL-responders.  This is an appropriate guideline.


Review of Jørgensen GF, et.al. Long-pulsed dye laser versus intense pulsed light for photodamaged skin

January 30, 2009

http://www.ncbi.nlm.nih.gov/pubmed/18563775

Lasers Surg Med. 2008 Jul;40(5):293-9.

Long-pulsed dye laser versus intense pulsed light for photodamaged skin: a randomized split-face trial with blinded response evaluation.

Jørgensen GF, Hedelund L, Haedersdal M.

Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Copenhagen, Denmark.

 

 

In this paper, Gitte Jørgensen reports a rarely seen type of study in the aesthetic space – a randomied comparison of two competing device technologies.  The study was co-sponsored by both device manufacturers, but neither manufacturer participated in the conduct or analysis of the study.  Most aesthetic device studies compare a device treatment to an untreated control, to show that the treatment causes some effect.  In contrast, this study compared the Candela VBeam Perfecta (long pulse 595nm dye laser) with the Ellipse Flex (Intense Pulsed Light) for the treatment of photodamaged skin, to see if the treatments caused different outcomes

The study was well-designed to demonstrate the differences with each type of treatment.  First, the patient population was homogenous (light skin females).  Reduction of patient variability reduces confounding of outcomes and enables smaller sample sizes.  Second, each study participant received a series of 3 split-face treatments with the one side randomized to each device type, which properly controls for non-study effects (e.g. additional sun exposure).  The use of the series of 3 treatments would magnify outcome differences, if there were any.  Third, the evaluation was performed on-site by a blinded, independent physician, to prevent bias and to prevent the introduction of photographic artifact.  Although blinding adequately prevents bias, agreement from multiple blinded observers would be useful to reduce individual subjectivity in the assessment of improvement.

While both devices demonstrated improved outcomes in this study, the long pulse 595nm dye laser achieved overall superior results, due to superior performance on vascular lesions.  Fourteen of 20 patients obtained better clearing of telangiectasias with the pulsed dye laser and the remainder saw no difference.  The difference in lightening was both statistically and clinically significant (i.e. the difference in lightening was visually apparent to the blinded reviewer and the patient). Both devices achieved similar improvements for irregular pigmentation and skin texture.  Neither device showed any improvement in wrinkles/rhytids.  Eighteen of 20 patients preferred the pulsed dye laser, both because of improved vascular clearance and because there was less treatment-related pain.

Despite an excellent study design, there are some limitations to the study conclusions.  The superior results of the pulse dye laser should not be considered definitive, as there was no-pre-defined study hypothesis to be proven.  The study was too small to determine whether there was a significant difference in the rates of adverse effects between the two devices.  Because both devices demonstrated improvement in outcomes, practitioners may be able to achieve pulsed-dye-laser results by simply performing additional IPL treatments.  Possibly, other IPL systems may perform better than the Ellipse product used in this study.