Prevalence of contact allergy in the general population: A systematic review and meta-analysis

A substantial number of studies have investigated the prevalence of contact allergy in the general population and in unselected subgroups of the general population. The aim of this review was to determine a median prevalence and summarize the main findings from studies on contact allergy in the general population. Published research mainly originates from North America and Western Europe. The median prevalence of contact allergy to at least 1 allergen was 21.2% (range 12.5-40.6%), and the weighted average prevalence was 19.5%, based on data collected on all age groups and all countries between 1966 and 2007. The most prevalent contact allergens were nickel, thimerosal, and fragrance mix. The median nickel allergy prevalence was 8.6% (range 0.7-27.8%) and demonstrates that nickel was an important cause of contact allergy in the general population and that it was widespread in both men and women. Numerous studies demonstrated that pierced ears were a significant risk factor for nickel allergy. Nickel was a risk factor for hand eczema in women. Finally, heavy smoking was associated with contact allergy, mostly in women. Population-based epidemiological studies are considered a prerequisite in the surveillance of national and international contact allergy epidemics.

Population-based studies about contact allergy are scarce.

We aimed to determine the prevalence of contact sensitization in the general population and to investigate associations with important sociodemographic and medical characteristics. Within a population-based nested, case-control study in Germany, we performed patch tests with 25 standard allergens in 1141 adults (50.4% female, age median 50 years). Additional information was obtained by a dermatologic examination, a standardized interview, and blood analysis. At least one positive reaction was exhibited by 40.0% of the subjects, with reactions most frequently observed to fragrance mix (15.9%), nickel (13.1%), thimerosal (4.7%), and balsam of Peru (3.8%). Women were sensitized more often than men (50.2% vs 29.9%, OR 2.36, CI 1.84-3.03), and this was also significant for fragrance mix, nickel, turpentine, cobalt chloride, and thimerosal. Contact sensitization was more frequent in subjects who reported adverse skin reactions (53.8% vs. 32.6%; OR 2.41, CI 1.85-3.14), and this was particularly true for sensitization to nickel (45.5% vs 8.8%, OR 8.64, CI 5.67-13.17) and fragrance mix (29.0% vs 14.0%, OR 2.51, CI 1.60-3.91) and the corresponding intolerance of fashion jewelry and fragrances. Contact sensitization decreased with increasing degree of occupational training (unskilled 45.9%, apprenticeship 40.1%, technical college 40.4%, and school of engineering 12.5%; P=0.023; trend test P=0.042). Significant associations of contact sensitization and presence of allergen-specific IgE antibodies, atopic eczema, or psoriasis were not observed. Frequency estimates for the general adult population based on these findings were 28.0% for overall contact sensitization and 11.4% for fragrance mix, 9.9% for nickel, and 3.2% for thimerosal. It is concluded that contact allergy is influenced by sociodemographic parameters and plays an important role in the general population.