Prevalence of contact allergy in the general population in different European regions

Background Population/based studies about contact allergy are scarce. Objectives To obtain reliable estimates of the prevalence of contact allergy in the general population in Europe. Methods A cross-sectional study of a random sample from the general population, aged 18-74 years, in five different European countries (Sweden, the Netherlands, Germany, Italy and Portugal). In total, 12 377 subjects were interviewed and a random sample (n = 3119) patch tested to TRUE Test panels 1-3 and Fragrance Mix (FM) II, hydroxyisohexyl 3-cyclohexene carboxaldehyde (HICC) and sesquiterpene lactone mix. A positive patch test reaction is considered as contact allergy. Results In total, 27.0% [95% confidence interval (CI) 25.5-28.5] had at least one positive reaction to an allergen of the European baseline series, with a significantly higher prevalence in women than in men. The highest age-standardized prevalences (>= 1%) were found for nickel (14.5%, 95% CI 13.2-15.8), thiomersal (5.0%, 95% CI 4.2-5.8), cobalt (2.2%, 95% CI 1.7-2.7), FM II (1.9%, 95% CI 1.5-2.5), FM I (1.8%, 95% CI 1.4-2.3), HICC (1.4%, 95% CI 1.0-1.9), p-tert-butylphenol formaldehyde resin (1.3%, 95% CI 0.9-1.7) and para-phenylenediamine (1.0%, 95% CI 0.6-1.3). Only nickel and thiomersal showed a statistically significantly different prevalence for contact allergy among the different European populations. Subjects reporting contact dermatitis in their lifetime (age-standardized prevalence 15.1%, 95% CI 13.8-16.3) had an increased risk for contact allergy (odds ratio 1.9, 95% CI 1.5-2.5). The risk of having a contact allergy was not increased in those with atopic dermatitis (prevalence 7.6%, 95% CI 6.7-8.6; odds ratio 1.0, 95% CI 0.7-1.4). Conclusions Contact allergy to at least one allergen of the European baseline series was diagnosed in more than one-quarter of the general European population. Therefore measures to improve the primary prevention of contact allergy have to be enforced.