Time trends of contact allergy to amodified European baseline series in Beijing between 2001 and 2006

Background. Monitoring trends of sensitivity rates in a population is useful for epidemiological surveillance. The time trends for sensitivity rates of allergens have not previously been reported in China. Objectives. The aim of the present study was to determine the prevalence and trends of contact allergy in patients with suspected allergic contact dermatitis in Beijing, China. Patients/Methods. A retrospective analysis of all patch test data from our database was performed. A total of 1354 patients with suspected allergic contact dermatitis between 2001 and 2006 were studied. Patch tests with 20 allergens or mixtures of allergens were performed and analysed. Results. Sensitivity to potassium dichromate (50.1%) was most frequent, and sensitivity to imidazolidinyl urea(3.0%) was least frequent. Increasing trends insensitivity rates for 10 allergens with significant linear regression were observed (p < 0.05), including mercapto mix, black rubber mix, potassium dichromate, formaldehyde, epoxy resin, benzocaine, ethylenediamine dihydrochloride, paraben mix, tixocortol-21-pivalate, and sesquiterpene lactone mix. Sensitivity rates for the other 10 allergens remained stable or showed only a trend (fragrance mix) towards an increase (p(trend) > 0.05). Conclusions. High sensitivity rates were observed in the study. Significant increasing trends in sensitivity rates for 10 allergens, probably reflecting increasing changes in exposure, were found.