Atopy and contact sensitisation: relationship reassessed

Background. Throughout medical literature, there are conflicting data on the relationship between atopy and contact sensitisation. Some authors believe that atopy is a protective factor against contact allergy, whereas others say it is a risk factor. Facing this contradiction, this study was undertaken to reassess the possible relationship.

Methods. In 5 vocational schools, 1 randomly selected class in each was invited to participate. Altogether 135 students were tested, 73 females and 62 males aged 18-19 years. As markers of atopy, positive skin prick tests, Phadiatop and elevated total IgE (>120 kU/l) were selected. Patch tests were used for the detection of contact sensitivity. Skin tests included 10 contact allergens and 16 aeroallergens relevant for this population. The tests were carried out and scored according to the ICDRG and EAACI guidelines. Statistical analysis of the relationships included Fisher's chi-square test and odds ratios.

Results. Positive patch tests (at least 1+ reaction) were found in 28.1% of the study subjects, positive prick test (wheal diameter at least 3 mm) in 23.7%, positive Phadiatop in 20.0%, and elevated total IgE in 23.7%. No statistically significant relationship between atopy markers and patch test results could be found. For each analysed feature, odds ratios remained close to the value of 1. As a "positive control" for the study design, the known relationship between female gender and positive patch test could be reconfirmed (for nickel: p=0.003, OR=12.0, 95%CI: 2.7-54.1).

Conclusion. In the general population, there is no (or negligible) correlation between atopy and contact sensitisation.

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