Search

Contact allergy (CA) surveillance networks provide information to a multitude of stakeholders, which is indispensable for evidence-based decision-making in the field of prevention. Methods and results of the German surveillance system on CA are reviewed and discussed with reference to other systems. The German network structure comprises 56 departments of dermatology and includes all patients who are patch-tested for suspected CA. Data analysis considers the results of patch testing and further pertinent information for each patient. Following aspects are addressed: (i) the description of the clinical population, (ii) evaluation of patch test reactions, (iii) relationship between patch test results and population characteristics. Trend analyses on chromate (decreasing), epoxy resin (increasing) and nickel (heterogeneous) served as examples for surveillance system analyses, with the identification of sentinel events, as well as proof of success or failure of prevention. In addition, external data sources can be used such as sales data of patch test preparations to estimate frequencies of sensitization on a population level. National prescription data of drugs and statistics of labelling of preservatives on cosmetics can be included, the latter two approaches allowing for risk estimates conferred by specific allergens.

Genetic factors presumably play a role in contact allergy (CA). There is, however, a lack of conclusive evidence from clinical studies. This may be on account of the strongly competing or modifying impact of exogenous factors, namely the potency of allergens and the intensity of exposure, and the fact that - in principle - everybody can be sensitized. Regarding phenotype, in contrast, polysensitization (PS) seems to indicate a subset of individuals at greater risk. In human sensitization experiments with dinitrochlorobenzene, induction was facilitated in PS, and elicitation enhanced. Recent clinical epidemiological data, taking confounders for PS, such as age, sex, and other skin diseases into account, demonstrated the following: (i) PS was the greatest risk factor to be sensitized to a number of (even weak) index allergens, indicating higher susceptibility on the level of induction; (ii) patch test reactions in PS patients were generally stronger indicating higher susceptibility on the level of elicitation. These findings are complemented by reports on polymorphisms of TNF-alpha and IL-16 in PS patients. Future studies on the genetics of CA should be performed in subgroups with PS, focussing on polymorphisms relevant for CA-specific and nonspecific (inflammatory) processes.

Background: This study assessed the hypothesis that a decreased exposure to childhood infectious diseases is associated with signs and symptoms of ‘atopic’ hypersensitivity diseases. Methods: A cross-sectional survey was performed among 1368 Spanish and German first-year university students between 1997 and 1999, including self-administered questionnaire data and serological tests. Results: No association between the disease outcomes and hepatitis A, Helicobacter pylori infection and herpes simplex infection was observed in logistic regression analyses, adjusting for potential confounders (centre, sex, smoking, parental education). In contrast, vaccination against hepatitis B was associated with a decreased risk for the outcomes allergic rhinitis (OR 0.63, 95% CI: 0.42–0.95) and total serum IgE above 100 U/ml (OR 0.56, 95% CI: 0.39–0.81). Conversely, seropositivity to HBc antigen was significantly associated with high total serum IgE (OR 2.04, 95% CI: 1.34–3.06). Conclusions: Our study partly confirmed and partly contradicted previous evidence and hypotheses, respectively, concerning the role of the infections considered. The observation of a decreased risk in persons vaccinated against hepatitis B warrants further, prospective investigation.

Background: Patch testing is the standard clinical procedure to prove contact sensitization. It is a common practice to attach multiple patch tests at the same time. However, synchronous reactions to unrelated allergens may not be completely unassociated. If so, the reaction in a given test field might be influenced by other positive test reactions in a distance-related degree. This article analyses whether there is a distance-related effect of synchronous positive patch test reactions on the outcome of a target patch test. Methods: Data collected from patients patch tested for diagnostic purposes with 15 standard allergens attached in a specific pattern between 1992 and 2004 in 20 centres in a Central European network were retrospectively evaluated. The association between the target patch test result (allergic vs negative reaction to the thiuram mix) and the number and cumulated strength of synchronous positive reactions (positive patch test load) to allergens placed in nearby or distant positions to the target patch was analysed by using logistic regression analysis. Results: The likelihood of a positive reaction to thiuram mix significantly increased with an increasing synchronous positive patch test load generated by positive reactions to allergens unrelated to thiuram mix. The effect of allergens neighbouring the target allergen was not significantly stronger than that of allergens placed in distant positions. Conclusion: For the interpretation of patch test results, the potentially enhancing effects of a synchronous positive patch test load should be considered. The local distribution of the patches on the back is, however, not critical.

The role of atopic eczema (AE) as risk factor for the development of allergic contact dermatitis is discussed controversially, as well as its influence on patch test results due to increased irritability. In this study, we analysed the pattern of positive patch test results to most frequent contact allergens in patients with AE (n = 9020) and age matched nonatopic (n = 15 263) individuals. The pattern and the frequencies of the observed sensitizations did not differ greatly from nonatopic individuals. Bufexamac is an exception: in AE patients sensitization is observed three times more often. For the other substances tested only minor differences were detected. Moreover, the frequencies of single, double or polyvalent sensitizations were nearly identical between the two groups. The analysis of the anatomical sites of dermatitis shows differences between the groups: in AE patients, the face (7.2%) and hand dermatitis (6.6%) was more common, and leg dermatitis (4.0%) less common. Analysis of occupation, suspected allergen source, and accompanying factors revealed no major differences between the both groups. Conclusion: The chronic and long-term exposure to external drugs and emollients presumably carries a risk for sensitization against specific contact allergens in AE patients. However, the sensitization of contact allergens differs surprisingly little between patients with or without AE.

Background: Patch test patients have two or more positive reactions to unrelated allergens more often than to be expected by chance. This study evaluates synchronous patch test reactions to test the hypothesis that in such cases an allergen-independent disposition for contact sensitization may be involved. Methods: Data of 87 834 patients tested with a standard patch test series in 42 centers of a Central European Network were retrospectively evaluated. Analyses were done for synchronous positive reactions of graded strength to nickel sulfate, fragrance mix, and to those five allergens that followed in frequency of positive results. All seven allergens selected were not related by chemical structure or exposure. Descriptive univariate and bivariate analyses as well as a polytomous logistic regression analysis were performed. Odds ratios with 95% confidence intervals were calculated. Results: With an increasing strength of a positive reaction to nickel or to fragrance mix the likelihood of further positive reactions to unrelated contact allergens increased significantly, and the mean strength of such additional reactions raised steadily with an increasing strength of a nickel or fragrance reaction. Conclusions: Our findings support the idea that patients who respond with a strong patch test reaction may have a particular general disposition to acquire contact sensitivity to additional unrelated allergens. They should therefore not only be advised to avoid their known allergen but in addition to minimize exposure other contact allergens.

Background: Previous research indicates that positive patch tests to nickel (II) sulphate, cobalt (II) chloride and potassium dichromate commonly occur together. Methods: To further examine the relationship between nickel, cobalt, chromate, and the factors that may potentially be related to concurrent sensitizations to two or all three metal allergens, data from the Information Network of Dermatology Departments (IVDK, http://www.ivdk.org) have been investigated. Results: Women had a higher conditional odds of concurrent nickel–cobalt (OR = 6.80; 95% CI: 5.65–8.19) and nickel–chromate (OR = 2.13; 95% CI: 1.67–2.72) reactions than men. Construction workers had a significantly higher odds of cobalt–chromate reactions (OR = 13.89; 95% CI: 10.36–18.64), while the odds of isolated cobalt allergy was only 0.92 (95% CI: 0.48–1.74). Patients with underlying atopic eczema/dermatitis syndrome had a 40–90% higher chance of any positive outcome, which involved chromate. Polysensitization, defined as the number of positive reactions to standard series substances other than nickel, cobalt, and chromate, was also significantly associated with the concurrent reactions; moreover, steady and significant effect gradients were noted. Conclusions: This research confirms the occupational nature of cobalt–chromate concurrent reactions, in particular, in construction workers. Polysensitization, which is considered to represent susceptibility to delayed-hypersensitivity in general, is also associated with the concurrent reactions to the metals. Hence, not only coupled exposure, but also individual susceptibility may be responsible for concurrent reactions to metals in man.