BC06: Efficacy of lasers and light-based devices in long-term hair reduction defined by body site-specific growth cycles: a systematic review
A. Krasniqi1 and S. Rajpara2,3
1University of Aberdeen and 2NHS Grampian, Aberdeen, UK, and 3Harley Street Dermatology Clinic, London, UK
Over 40% of women in the general population suffer from adverse psychological effects due to unwanted hair (Blume-Peytavi U, Gieler U, Hoffmann R et al. Unwanted facial hair: affects, effects and solutions. Dermatology 2007; 215: 139–46). Laser and light-based devices provide scope for ‘hair removal’; however, their long-term efficacy and factors affecting this efficacy remain undetermined. Hair repeatedly undergoes three growth cycle phases: anagen (growth), catagen, (regression) and telogen (rest). The time taken to complete a full growth cycle varies depending on body site (Laughlin SA, Dudley DK. Long-term hair removal using a 3-millisecond alexandrite laser. J Cutan Med Surg 2000; 4: 83–8). Thus, body site-specific growth cycles should be accounted for when measuring ‘long-term’ outcomes. The aim of this study was to determine the efficacy of laser and light-based devices in long-term hair reduction and the effect of different body sites on efficacy. A systematic review of randomized controlled trials (RCTs) was conducted. Trials selected for inclusion were required to have follow-up periods equal to or greater than the length of one complete hair growth cycle in the specific body site treated. Only five eligible RCTs were identified for inclusion and comprised 223 patients. The average long-term hair reduction reported for treatment with neodymium:yttrium aluminium garnet (Nd:YAG) laser (n = 2) ranged from 30% to 74%, with the greatest long-term hair reduction seen in leg hair (1-year growth cycle) and lowest in facial hair (6-month growth cycle). Diode laser treatment (n = 3) produced an average hair reduction of 32–69% in the long term. Average long-term hair reduction in trials of alexandrite laser (n = 3) ranged from 35% to 84%. The greatest long-term hair reduction was seen in the leg area and lowest in the facial area. Three trials investigated the long-term efficacy of intense pulsed-light therapy with average long-term hair reductions of 53–27%. The lowest long-term hair reduction was seen in treating facial hair (6-month growth cycle) and greatest in treating axillary hair (7-month growth cycle). Overall, synthesis of the limited data currently available on the long-term efficacy of laser and light-based ‘hair-removal’ devices did not demonstrate the superiority of one device over another. However, a trend towards greater long-term hair reduction on body sites with longer hair growth cycles was observed. Therefore, to provide more accurate data on treatment outcomes and better inform patient and practitioner decisions, it is important that follow-up periods in studies assessing the efficacy of laser and light-based devices in hair reduction account for variation in hair growth cycles at individual body sites.
