Time trends of contact allergy to a modified 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 in sensitivity 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.