Response to: “Treatment of hidradenitis suppurativa using a long-pulsed hair removal neodymium:yttrium-aluminium-garnet laser: A multicenter, prospective, randomized, intraindividual, comparative trial”
Authors: Nneamaka Ezekwe, David M. Ozog, Iltefat H. Hamzavi
Journal: Journal of the American Academy of Dermatology (2021)

To the Editor: Passeron and colleagues published findings on neodymium:yttrium-aluminium-garnet (Nd:YAG) laser for hidradenitis suppurativa (HS) and should be commended for conducting the first multicenter trial. Their study was conducted over 30 weeks across 8 centers in France and included 36 patients with skin phototypes (SPT) I-V. However, only 2.8% were SPT V. There are significant differences between the work by Passeron et al and our research at the Henry Ford Hospital, which were the first prospective trials to assess the efficacy of Nd:YAG in HS and contained a wider, more generalizable variation in SPTs, with 22.7% of V-VI.1Tierney E. Mahmoud B.H. Hexsel C. Ozog D. Hamzavi I. Randomized control trial for the treatment of hidradenitis suppurativa with a neodymium-doped yttrium aluminium garnet laser.Dermatol Surg. 2009; 35: 1188-1198https://doi.org/10.1111/j.1524-4725.2009.01214.xCrossref PubMed Scopus (113) Google Scholar,2Mahmoud B.H. Tierney E. Hexsel C.L. Pui J. Ozog D.M. Hamzavi I.H. Prospective controlled clinical and histopathologic study of hidradenitis suppurativa treated with the long-pulsed neodymium:yttrium-aluminium-garnet laser.J Am Acad Dermatol. 2010; 62: 637-645https://doi.org/10.1016/j.jaad.2009.07.048Abstract Full Text Full Text PDF PubMed Scopus (95) Google Scholar There were key differences in the treatment parameters between these studies. Our study showed sustained improvement of treated lesions, and as one of the largest HS centers in North America, this has been supported over a decade of treating several hundred patients (I.H. Hamzavi, personal communication, September 2021). We have a standard for treating HS lesions (Table I) and significantly more effects occur with second pulses if given before tissue temperature returns to baseline. It is unclear how the inflammatory areas were treated in the Passeron et al study, and there may have been variability as few patients were treated at each center.Table ILaser settings for CO2 excisional surgery for hidradenitis suppurativaHenry Ford Health System Department of Dermatology laser settingsFor all skin types: Double pulsation of inflammatory lesions (nodules, abscesses) Single pulsation of surrounding areasLaser type: Neodymium:yttrium-aluminium-garnet laser 1064 nm (Cutera Inc) using 10-mm spot with pre-, parallel, and post-coolingFitzpatrick skin phototypePulse durationFluence I-III20 milliseconds35-60 J/cm2 IV-VI35 milliseconds35-60 J/cm2 Open table in a new tab There were also differences in the measurable outcomes used to assess treatment efficacy. Passeron et al assessed the number of inflammatory lesions at baseline, week 22, and week 30 as the primary end point and used the Hidradenitis Suppurativa Clinical Response as the secondary end point. The primary end point was significant at 1 month but not at 3 months, and although 73.7% of patients achieved Hidradenitis Suppurativa Clinical Response of the treated side compared with 52.6% of the control, there was no significant difference (P = .27). The lack of significance could be explained by the index chosen. Hidradenitis Suppurativa Clinical Response does not measure the improvement or formation of sinus tracts. If sinus tracts developed on the nontreated side but not on the treated side, this would not have been captured and would miss the true magnitude of effect. Scoring systems such as HS-LASI and IHS4 weight sinus tract formation over other inflammatory lesions and may be more appropriate to measure disease burden in clinical trials. Previous HS laser study trials that exhibited significant degrees of improvement used HS-LASI.1Tierney E. Mahmoud B.H. Hexsel C. Ozog D. Hamzavi I. Randomized control trial for the treatment of hidradenitis suppurativa with a neodymium-doped yttrium aluminium garnet laser.Dermatol Surg. 2009; 35: 1188-1198https://doi.org/10.1111/j.1524-4725.2009.01214.xCrossref PubMed Scopus (113) Google Scholar, 2Mahmoud B.H. Tierney E. Hexsel C.L. Pui J. Ozog D.M. Hamzavi I.H. Prospective controlled clinical and histopathologic study of hidradenitis suppurativa treated with the long-pulsed neodymium:yttrium-aluminium-garnet laser.J Am Acad Dermatol. 2010; 62: 637-645https://doi.org/10.1016/j.jaad.2009.07.048Abstract Full Text Full Text PDF PubMed Scopus (95) Google Scholar, 3Abdel Azim A.A. Salem R.T. Abdelghani R. Combined fractional carbon dioxide laser and long-pulsed neodymium : yttrium-aluminium-garnet (1064 nm) laser in treatment of hidradenitis suppurativa; a prospective randomized intra-individual controlled study.Int J Dermatol. 2018; 57: 1135-1144https://doi.org/10.1111/ijd.14075Crossref PubMed Scopus (25) Google Scholar Finally, there was no significant difference in the number of flares between the treated and untreated sides. However, there is no established definition of disease flare. Patient-reported outcomes support that Nd:YAG laser may reduce flares, but standardizing the definition of flare is essential to categorize treatment success accurately.4Vossen A.R.J.V. van der Zee H.H. Terian M. van Doorn M.B.A. Prens E.P. Laser hair removal alters the disease course in mild hidradenitis suppurativa.J Dtsch Dermatol Ges. 2018; 16: 901-903https://doi.org/10.1111/ddg.13563Crossref Scopus (21) Google Scholar Fortunately, HS flare is one of the core outcomes in the Core Outcome Set for HS clinical trials that is currently being developed by the group HISTORIC.5Kirby J.S. Moore B. Leiphart P. et al.A narrative review of the definition of "flare" in hidradenitis suppurativa.Br J Dermatol. 2020; 182: 24-28https://doi.org/10.1111/bjd.18035Crossref PubMed Scopus (14) Google Scholar Despite differences, we applaud the authors and editors of the JAAD for publishing this important and informative trial. Nd:YAG laser offers a less invasive and less expensive option for the treatment of Hurley stage I and II and may reduce the progression of HS to stage III. Well-designed clinical trials like this add to our knowledge of best practices in management. Additional studies will hopefully provide a basis for standardizing this treatment. Dr Hamzavi is on the advisory board of AbbVie; is the principal investigator for Pfizer Inc, Bayer, Lenicura, and Incyte; is a consultant for Incyte, Pfizer Inc, UCB, and Boehringer Ingelheim; and is the president of HS Foundation and receives no compensation for this role. Drs Ozog and Ezekwe have no conflicts of interest to declare. All grants have been paid to the institution.