A PROSPECTIVE LONGITUDINAL-STUDY OF THE OUTDOOR BEHAVIOR AND SYMPTOMSOF PHOTOSENSITIVE PATIENTS

The purpose of this study was to determine the measures that photosens itive patients use to control their sun exposure. Each week from March until September 1995, 30 patients with polymorphic light eruption (PL E) and 17 patients with chronic actinic dermatitis (CAD) returned a se t of reply paid postcards on which they recorded information about the ir outdoor behaviour and symptoms. The principal differences between t he two groups were that CAD patients had a much greater incidence of s ymptoms despite making more use of protective measures such as coverin g arms, wearing hats and applying sunscreen, than patients with PLE. A nd that as summer approached the PLE patients spent more time outdoors , whereas there was less seasonal variation in this respect among CAD patients. Tentative conclusions drawn from mathematical modelling indi cated that the incidence of rash on a particular day was influenced by ambient ultraviolet radiation and length of time spent outdoors, Ther e were indications that wearing a hat and keeping the arms covered off ered some protection, whereas use of sunscreen may actually increase t he likelihood of symptoms.