PURPOSE OF THE STUDY.
To evaluate for agreement between the results of skin prick tests (SPTs) and serum-specific immunoglobulin E (SSIgE) testing for sensitivity to environmental aeroallergens and food allergens in children. The authors of this study also assessed the associations between SPTs with positive results and the presence of atopic dermatitis in children from ages 1 to 6 years.
Test results were available for 204 children from rural areas in France, who were recruited through the Protection against Allergy: Study in Rural Environments (PASTURE) project, which included a cohort of European children managed from birth to 10 years of age to determine the effect of farm exposure on the occurrence of allergies.
SPTs, atopic dermatitis evaluations using Scoring Atopic Dermatitis Severity Scores, and SSIgE levels were completed at the following ages: 1 year, 4.5 years, and 6 years. SPTs and SSIgE testing were performed for a panel of common aeroallergens and food allergens at each visit. An overall SPT with positive results was defined as at least 1 SPT resulting in a reaction covering ≥3 mm of skin, induced by an allergen from among the following categories: seasonal aeroallergen, perennial aeroallergen, food allergen, or any allergen. An overall SSIgE test with positive results was defined as at least 1 SSIgE test with positive results from among the same categories, and 4 different cutoffs for positive results of SSIgE testing were used for analysis (0.2, 0.35, 0.7, and 3.5 IU/mL). κ-Coefficients were calculated to assess for agreement, and a value of >0.61 was defined as good agreement.
One hundred and thirty-seven children completed all 3 study visits. Overall, SPTs and SSIgE tests had inconsistent results, despite analyzing with different immunoglobulin E cutoffs. There were some specific exceptions in which the 2 tests trended toward agreement, but that agreement level did not reach statistical significance. SPT and SSIgE test results approached agreement for both perennial and seasonal aeroallergens at 6 years of age when they used an immunoglobulin E cutoff of >0.7 IU/mL (κ-coefficient = 0.69, 95% confidence interval [CI]: 0.52–0.86; and κ-coefficient = 0.66, 95% CI 0.49–0.83, respectively). Test results trended toward consistency between SPTs and SSIgE testing at 6 years of age when using an SSIgE cutoff of >3.5 IU/mL, but only for seasonal aeroallergens (κ-coefficient = 0.69, 95% CI: 0.51–0.87). As for the occurrence of atopic dermatitis at any time point during the follow-up period lasting up to 6 years of age, positive SPT results at 1 year of age to at least 1 aeroallergen or food allergen was associated with an increased diagnosis of atopic dermatitis (P = .007). The majority of these atopic dermatitis patients with positive results from SPTs at 1 year of age were sensitized to food (91.6%), most commonly eggs (83%).
There is poor agreement between the results of SPTs and SSIgE tests in early childhood, particularly in testing for sensitivity to food allergens and in testing at a younger age; therefore, these 2 tests cannot be used interchangeably. At least 1 SPT with positive results for sensitivity to an aeroallergen or food allergen at 1 year of age was predictive of the occurrence of atopic dermatitis during the follow-up period lasting up to 6 years of age.
This birth cohort study is unique in that it evaluates for consistency between the results of SPTs and SSIgE levels over time in the early childhood population. Exploration in a more diverse population that is not limited to the rural setting and in a larger cohort would be beneficial because a low number of subjects in this study had positive SPT results. The poor correlation between SPT and SSIgE test results seen in this study provides additional insight regarding the development and natural course of sensitization in early childhood and suggests that correlation with clinical outcomes remains essential.
- Copyright © 2017 by the American Academy of Pediatrics