Letters

Many patients with psoriasis use sunbeds

EDITORPsoriasis usually improves in sunlight, but many patients look for an alternative source of ultraviolet light, either because they are embarrassed to sunbathe in public or because of the unpredictable availability of sunlight. Sunbeds that emit ultraviolet A light might seem an attractive option, but their use, at least for tanning purposes, is discouraged by dermatologists and other healthcare workers. ^{1 2}

To investigate our patients' use of sunbeds, we posted a questionnaire to the latest 339 patients who were new referrals aged 16-65 years and in whom a diagnosis of plaque psoriasis was made (localised and guttate psoriasis were excluded). All had had psoriatic lesions for at least a year when they received the questionnaire. We received replies from 248 patients (response rate 73% (248/339)), of whom 128 (52%) had used a sunbed to treat their psoriasis. Linear logistic regression showed highly significant and non-interacting effects of age and sex (P<0.001), indicating that sunbed use was generally higher among females and tended to decrease with increasing age (see table). Of the 97 patients who reported the effect of sunbed use on their psoriasis, two found that their condition worsened, 17 reported no change, and 78 reported an improvement. We detected no associations between perceived efficacy and age, sex, or tanning ability (² P>0.1). Of the sunbed users, 56% (72/128) reported that they had treated themselves more than 20 times in a year, and 13% (17/128) had treated themselves more than 80 times in a year.

Our results suggest that a larger proportion of patients with psoriasis use sunbeds than the 13% reported for randomly selected British adults³ and that their frequency of use may also be higher. Ultraviolet A accounts for about 99% of the ultraviolet emission from a typical sunbed lamp. Although highly effective for treating psoriasis when combined with psoralen (PUVA treatment), the effect of ultraviolet A alone is unknown as controlled trials have not been performed. Exposure to ultraviolet A can cause several adverse reactions in the skin and is a probable risk factor for non-melanoma skin cancer. Of most concern is whether the risk of melanoma attributed to sunbed use⁴ will become significantly higher with longer follow up of sunbed users. The British Photodermatology Group suggested a maximum of 20 exposures annually for people who, despite its advice, wished to use sunbeds.¹ While it has been argued that this recommended maximum is pragmatic,³ it is worrying that this exposure level was exceeded by over half of our patients who used sunbeds to treat their psoriasis.