[595 nm pulse dye laser therapy for viral warts: a single-blind randomized comparative study versus placebo]

Pulse dye laser (PDL) appears an attractive method to treat warts. However, data concerning the efficacy of this approach are based chiefly upon open clinical studies or case reports and results vary widely from one study to another. The purpose of this study was to compare the efficacy and safety of PDL with a placebo in the treatment of a homogeneous group of patients presenting palmoplantar warts.

This was a randomized, prospective, placebo-controlled, single-blind study conducted between December 2004 and July 2005 in patients consulting for palmoplantar warts at the Dermatology Department of the University Teaching Hospital of Nice. The treatment settings used for the 595-nm PDL were as follows: spot diameter 5 mm, pulse duration 0.45 ms, fluence 9 J/cm2 with 5 passes at a frequency of 1 Hz. Cryogen spray cooling (system incorporated in the machine) was given at a rate of 50 spurts of 40 ms prior to each laser pulse. In patients in the placebo group, cooling pulses alone were given. For the plantar warts (in both groups), hyperkeratosis was removed manually with a scalpel before each session. A maximum of three sessions was administered at 3-week intervals. The type and number of warts was counted and recorded in a treatment schedule before the start of therapy, at each session and 5 weeks after the final session. The global safety of the treatment was evaluated using a visual analog scale between 0 (intolerable) and 10 (completely safe).

Nineteen patients were included in the laser group and 16 were included in the placebo group. Sixty-four per cent (48/75) of warts in the laser group resolved completely compared with 13% (4/30) in the placebo group (p<0.001). In the PDL group, 6 of 19 patients (31.5%) no longer had warts by the end of the study compared with 3 of 16 patients (18.75%) in the placebo group (p=0.46). The global safety score of the treatment as assessed by the patients themselves was 8.31 in the laser group and 9.81 in the placebo group.

Pulse dye laser appears to be an effective treatment in palmoplantar warts but the efficacy of this method seems to be only equivalent to that of standard treatments (cryotherapy or salicylic acid preparations). Safety is excellent and constitutes one of the major advantages of this technique. The absence of any proven superiority over the standard treatments in terms of efficacy, coupled with the high costs involved, means that PDL should only be used second-line therapy in patients wishing to avoid constraints affecting their professional activity.