Results and Assessment of Photopatch Testing in Spain: Towards a New Standard Set of Photoallergens

Abstract

Introduction While the standardization of exploration with photoallergy tests or photopatch testing runs its course in Europe, we have carried out an epidemiological study about the current situation of photoallergy in our country. Material and methods We have gathered the results of photopatch testing in seven hospital centres of Madrid, Cataluña, Galicia and Comunidad Valenciana during the years 2004 and 2005. The exploration has included, at least, the standard set of the Spanish Photobiology Group (GEF), with 16 (photo) allergens, that have been irradiated with 10 J/cm 2. We have assessed the total number of explored patients, their sex, present, past or unknown relevance of positive photopatch testing, cross reactions, and allergens responsible for photosensitization. Results Of 224 patients explored by photopatch testing, 39.3% show one or more positive tests. Seventyone percent (103) were considered relevant with respect to clinical history, 14 cases (9.6%) were cross reactions, and 28 (19.3%) were considered of unknown relevance. The most prevalent allergens were nonsteroidal antiinflammatory drugs, specially ketoprophen (43 patients), followed by bencydamine (7 patients) and etofenamate (5 patients). The mixture of four sunscreens from the standard set of the GEF only detected 10 of 16 patients with photoallergy to sunscreens. Photopatch testing of unknown relevance was mainly due to antiseptics (fenticlor) and topical antihistamines. Conclusions We propose the modification of the standard set of photoallergens from the GEF, that should include the majority of nonsteroidal antiinflammatory drugs and sunscreens available in Spain. Ketoprophen continues to be the most frequent photoallergen in our country. It is also important for the cross sensitizations that may present. Sunscreens should be explored separately and not in form of a mixture.