Patterns of tree nut sensitization and allergy in the first 6 years of life in a population-based cohort

Abstract

Longitudinal population-based data regarding tree nut allergy are limited. We sought to determine the population prevalence of tree nut allergy at age 6years and explore the relationship between egg and peanut allergy at age 1year and development of tree nut allergy at age 6years. A population-based sample of 5276 children was recruited at age 1year and followed up at age 6years. At age 1year, allergies to egg and peanut were determined by means of oral food challenge, and parents reported their child's history of reaction to tree nuts. Challenge-confirmed tree nut allergy was assessed at age 6years. At age 1year, the prevalence of parent-reported tree nut allergy was 0.1% (95% CI, 0.04% to 0.2%). Only 18.5% of infants had consumed tree nuts in the first year of life. At age 6years, challenge-confirmed tree nut allergy prevalence was 3.3% (95% CI, 2.8% to 4.0%), with cashew the most common (2.7%; 95% CI, 2.2% to 3.3%). Of children with peanut allergy only at age 1year, 27% (95% CI, 16.1% to 39.7%) had tree nut allergy at age 6years compared with 14% (95% CI, 10.4% to 17.9%) of those with egg allergy only and 37% (95% CI, 27.2% to 47.4%) of those with both peanut and egg allergy. Tree nut allergy is uncommon in the first year of life, likely because of limited tree nut consumption. At age 6years, tree nut allergy prevalence is similar to peanut allergy prevalence. More than a third of children with both peanut and egg allergy in infancy have tree nut allergy at age 6years. Understanding how to prevent tree nut allergy should be an urgent priority for future research.