Allergens responsible for allergic contact dermatitis among children: a systematic review and meta-analysis

Objectives. To evaluate the proportion of positive reactions for allergens tested in children and to identify allergens with positive reactions in at least 1% of them. Methods. This was a systematic review of studies in PubMed (1966-2010) investigating allergens in at least 100 enrolled children. Proportions of positive reactions for each allergen were combined with random effects models across studies. Results. We included 49 studies with available data on 170 allergens. Each study tested a median of two allergens. Among the 94 allergens evaluated by at least two studies, 58 had estimates of positive reactions of at least 1% by random effects calculations, and for 21 of them the 95% confidence interval ensured that the proportion of positive reactions was at least 1%. The top five allergens tested by at least two studies included nickel sulfate, ammonium persulfate, gold sodium thiosulfate, thimerosal, and toluene-2,5-diamine (p-toluenediamine). For most allergens, the proportion of positive reactions was higher in studies published after 1995 than in earlier studies (p = 0.0065). Conclusions. This meta-analysis offers guidance on which allergens are most prevalent in the paediatric population and should have priority for inclusion in standardized allergen series.