Natural History of Peanut Allergy and Predictors of Resolution in the First 4 Years of Life: A Population-Based Assessment

Abstract

RATIONALE: There is no prospectively collected data available on the natural history of peanut allergy in early childhood. Previous studies have been biased by failure to challenge high-risk children when IgE antibody levels are high, potentially biasing towards persistent allergy.We sought to describe the natural history of peanut allergy between ages 1 and 4 years and develop thresholds for skin prick test (SPT) and serum specific-IgE (sIgE) that have 95% positive predictive value (PPV) to persistent peanut allergy. METHOD(S): Challenge-confirmed peanut allergic 1-year-old infants (n=156) from the population-based, longitudinal HealthNuts Study (n=5276) were followed up at 4 years of age with repeat oral food challenge, SPT and sIgE (n=103). Challenges were undertaken at both ages 1 and 4 years, irrespective of risk profile. RESULT(S): Peanut allergy resolved in 22% (95% CI 14-31%) of children by age 4 years. Falling wheal size predicted tolerance while increasing wheal size was associated with persistence. Thresholds for SPTand sIgE at age 1 with 95% PPV to persistent peanut allergy are SPT > 13mm and sIgE >= 5.0 kU/L. Thresholds for SPT and sIgE at age 4 with 95% PPV to persistent peanut allergy are SPT >= 8mm and sIgE >= 2.1 kU/L. Ara h2, tree nut and house dust mite sensitisation, coexisting food allergies, eczema and asthma were not predictive of persistent peanut allergy. CONCLUSION(S): These thresholds are the first to be generated from a unique dataset where all participants underwent OFC at both diagnosis and follow-up, irrespective of SPT and sIgE.