Evaluation of Skin Prick Test Reading Time at 10 versus 15 min in Young Infants

Introduction: The optimal time point for reading the mean wheal diameter (MWD) of a skin prick test (SPT) in infants is not established. We aimed to assess if either of two reading time points of the SPT, 10 or 15 min, was superior to detect allergic sensitization (AS) in 6-month-old infants. Methods: In 1,431 6-month-old infants from the population-based Preventing Atopic Dermatitis and ALLergies in children (PreventADALL) mother-child cohort, the SPT was performed with standard solutions for egg, cow’s milk, peanut, wheat, soy, birch, timothy, dog, and cat. The MWD was measured after 10 and 15 min. AS was defined as a positive SPT with MWD ≥2 mm larger than the negative control. Results: Overall, 149 (10.4%) infants were sensitized to at least one allergen at 10 and/or 15 min, while 138 (9.6%) had a positive SPT at 10 min and 141 (9.9%) at 15 min. A total of 12,873 allergen pricks were performed with 212 (1.6%) being positive at any time point, 194 (1.5%) positive at 10 min, and 196 (1.5%) positive at 15 min. The mean (95% CI) histamine MWD of 3.8 (3.8, 3.9) mm at 10 min was significantly larger than the 3.6 (3.6, 3.7) mm at 15 min. Discussion/Conclusions: Reading the SPT after both 10 and 15 min increased the number of 6-month-old infants with documented AS compared to reading after one time point only. As neither 10 nor 15 min reading time was superior to the other in detecting AS, our results indicate that readings at both time points should be considered. However, the histamine MWD was significantly larger at 10 min compared to 15 min. Reappraisal of SPT reading in infancy may be warranted

Impaired skin barrier and allergic sensitization in early infancy

Background: Factors predicting allergic sensitization in the first 6 months of life are poorly understood. We aimed to determine whether eczema, dry skin, and high transepidermal water loss (TEWL) at 3 months were associated with allergic sensitization at 6 months of age and, secondarily, to establish whether these characteristics predicted sensitization from 3 to 6 months of age. Methods: At 3 months of age, 1,994 infants from the population-based PreventADALL birth cohort in Norway and Sweden were assessed for eczema and dry skin on the cheeks and/or extensors; impaired skin barrier function, defined as TEWL in the upper quartile (>9.4 g/m(2)/h), and allergen-specific IgE levels <0.1 kU(A)/L, available in 830. At 6 months, we assessed allergic sensitization to any food (egg, cow's milk, peanut, wheat, soy) or inhalant (birch, timothy grass, dog, and cat) allergen by a skin prick test wheal diameter >= 2 mm larger than negative control. Results: Any sensitization was found in 198 of the 1,994 infants (9.9%), the majority to food allergens (n = 177, 8.9%). Eczema, dry skin, and high TEWL at 3 months increased the risk of sensitization at 6 months; adjusted odds ratios 4.20 (95% CI 2.93-6.04), 2.09 (95% CI 1.51-2.90) and 3.67 (95% CI 2.58-5.22), respectively. Eczema predicted sensitization with 55.6% sensitivity and 68.1% specificity; dry skin with 65.3% sensitivity and 57.3% specificity; and high TEWL with 61.7% sensitivity and 78.1% specificity. Conclusion: Eczema, dry skin, and high TEWL at 3 months predicted allergic sensitization at 6 months of age

Early food intervention and skin emollients to prevent food allergy in young children (PreventADALL): a factorial, multicentre, cluster-randomised trial

Background: Primary prevention of food allergy by early introduction of allergenic foods seems promising. We aimed to determine whether early food introduction or the application of regular skin emollients in infants from a general population reduced the risk of food allergy. Methods: This 2 × 2 factorial, cluster-randomised trial was done at Oslo University Hospital and Østfold Hospital Trust, Oslo, Norway, and Karolinska University Hospital, Stockholm, Sweden. Infants of women recruited antenatally at the routine 18-week ultrasound examination were cluster-randomised at birth to the following groups: (1) no intervention group; (2) the skin intervention group (skin emollients; bath additives and facial cream; from age 2 weeks to <9 months, both at least four times per week); (3) the food intervention group (early complementary feeding of peanut, cow's milk, wheat, and egg from age 3 months); or (4) combined intervention group (skin and food interventions). Participants were randomly assigned (1:1:1:1) using computer-generated randomisation based on clusters of 92 geographical areas and eight 3-month time blocks. Study personnel performing clinical assessments were masked to group allocation. The primary outcome was allergy to any interventional food at 36 months of age. The primary efficacy analysis was done by intention-to-treat analysis, which included all participants who were randomly assigned, apart from three individuals who withdrew their consent. This was a study performed within ORAACLE (the Oslo Research Group of Asthma and Allergy in Childhood; the Lung and Environment). This study is registered as ClinicalTrials.gov, NCT02449850. Findings: We recruited 2697 women with 2701 pregnancies, from whom 2397 newborn infants were enrolled between April 14, 2015, and April 11, 2017. Of these infants, 597 were randomly assigned to the no intervention group, 575 to the skin intervention group, 642 to the food intervention group, and 583 to the combined intervention group. One participant in each of the no intervention, food intervention, and skin intervention groups withdrew consent and were therefore not included in any analyses. Food allergy was diagnosed in 44 children; 14 (2·3%) of 596 infants in the non-intervention group, 17 (3·0%) of 574 infants in the skin intervention group, six (0·9%) of 641 infants in the food intervention group, and seven (1·2%) of 583 infants in the combined intervention group. Peanut allergy was diagnosed in 32 children, egg allergy in 12 children, and milk allergy in four children. None had allergy to wheat. Prevalence of food allergy was reduced in the food intervention group compared with the no food intervention group (risk difference -1·6% [95% CI -2·7 to -0·5]; odds ratio [OR] 0·4 [95% CI 0·2 to 0·8]), but not compared with the skin intervention group (0·4% [95% CI -0·6 to 1· 5%]; OR 1·3 [0·7 to 2·3]), with no significant interaction effect (p=1·0). Preventing food allergy in one child required early exposure to allergenic foods in 63 children. No serious adverse events were observed. Interpretation: Exposure to allergenic foods from 3 months of age reduced food allergy at 36 months in a general population. Our results support that early introduction of common allergenic foods is a safe and effective strategy to prevent food allergy