Because controlled comparative studies of laser hair removal systems are lacking, dermatologists often have to compare several studies and draw their own conclusions, Christine C. Dierickx, M.D., said.

At this point, light systems used for hair removal include ruby, alexandrite, diode, and Nd:YAG lasers, as well as the flashlamp pulsed light system, said Dr. Dierickx, who practices in Boom, Belgium, but is currently a visiting faculty member at Harvard Medical School.

"The laser is an effective hair removal system, but we need to avoid creating false expectations in patients. We need also to be wary of pressure from laser companies' marketing departments," she said at the 57th annual meeting of the American Academy of Dermatology.

For the dermatologist who would like to offer laser hair removal, it is difficult to compare the different devices beacuse no controlled comparative studies have been performed. Dr. Dierickx said comparisons are further complicated by the lack of standardized efficacy parameters by which to judge a hair removal system.

"Efficacy should be evaluated by the hair count before and after treatment," she said. "The patient should experience one complete growth cycle for that particular body area, plus an additional six months' recovery time, before permanent hair loss can be claimed."

FOLLOW-UP DIFFERS BY SITE

The hair regrowth cycle differs by anatomical site. For the facial beard areas, the ideal follow-up period after laser treatment would be approximately 20 months. Follow-up periods should be 10 to 12 months for the eyebrows, 12 to 18 months for the legs, back and axilla; and 9 to 13 months for the arms, thighs, bikini area and upper lip.

"These are the minimum follow-up times before you can claim permanent hair loss for these areas," Dr. Dierickx said.

Several studies indicate the efficacy of a light-based hair removal system increases with higher fluences and with multiple treatments. In a multicenter study involving the ruby Epilaser (Palomar), Dr. Dierickx and colleagues treated 220 patients, of which 175 were followed for at least 6 months or longer after the last treatment. The number of treatments varied between 1 and 6, with a mean of 3. Patients of skin types I to V were involved. The different body sites used included the face, chest, armpits, arms, back, abdomen, bikini areas, and legs. Operators used a mean fluence of 34J/cm2, with 7 mm or 10 mm spot sizes. Efficacy was graded blindly from pre- and post-pictures.

Follow-up of the 175 patients showed 60 percent had greater than 75 percent hair loss.

"Legs, armpits, and chests responded better than backs and upper lips," she said.

Two other studies investigated the diode and ruby lasers, respectively, with patients followed at least two years in the ruby study and one year in the diode study. In the ruby study, 77 percent of the 100 participants had permanent hair reduction. The test sites were either on the back or legs. Half of each patient's 12 sites received one treatment; the other half received two treatments. Each patient was tattooed at each of the 4-by-3 cm test sites to ensure accuracy; each of the sites on each patient were treated with different fluences, ranging from 20J/cm2 to 40J/cm2.

Digital images of each test site were stored to allow for hair counts. Follow-up visits were at one, three, six, nine, 12, and 24 months after beginning treatment.

"We found a dose response such that the higher the fluence, the higher the percentage of hair loss. There is also an additive effect with a second treatment," Dr. Dierickx said. "We also found that the hair loss we saw at six months continued at 12 months and 24 months."

The diode study had a one year follow-up and included 100 patients with eight test sites. Investigators again compared increasing fluences and one vs. two treatments.

"We had the same dose response and additive effects findings for the diode as for the ruby, and we again saw a stabilization of hair counts at six months," Dr. Dierickx said. "In this study, 89 percent of patients had a permanent hair reduction. Another advantage to the diode was that we could treat dark skin types more safely, even skin type VI."

Palomar funded the research for the different studies. Dr. Dierickx has no proprietary interest in any laser manufacturer.