Peanut allergic children residing in Olmsted County, MN: an examination of the prevalence in 2007, incidence rates from 1999-2007 and association between peanut-specific IgE level, tolerance and reaction severity.

Abstract

INTRODUCTION Peanut allergy is a significant concern due to increased prevalence over the last few decades, potential severity of a reaction, and the large percentage of children who do not acquire tolerance. This dissertation evaluated rates of diagnosis over time and examined whether peanut-specific IgE level has clinical relevance regarding tolerance and reaction severity. METHODS Data on all children with a peanut allergy diagnosis between 1999-2007 in Olmsted County, MN was collected using the Rochester Epidemiology Project. The first study estimated the prevalence in 2007 and incidence rate of peanut allergy diagnoses from 1999-2007. This study further examined whether the number of peanut allergy diagnoses from 1999-2007 varied by reaction severity. The second study estimated the percentage of children that developed tolerance to peanuts and assessed the association between peanut-specific IgE level and tolerance. The third study evaluated the association between peanut-specific IgE level and reaction severity. RESULTS The 2007 prevalence of peanut allergy was 0.59%. There were statistically significant lower rates of peanut allergy diagnoses among females (82.0%) as compared to males and among children aged 3-17 years (99.9%) as compared to those aged 0-2 years. There was a significant 1.7-fold increase in peanut allergy diagnoses from 3.84 cases per 10,000 children in 1999-2001 to 6.53 per 10,000 children in 2005-2007. There was not a significant difference in the number of children having had mild as compared to moderate/severe reactions over time. In this sample, 16.4% developed tolerance to peanuts. Children with peanut-specific IgE class levels 4-6 as compared to those with levels 1-3 had a significant 91.0% reduced likelihood to develop tolerance after adjustment for number of atopic conditions and a 2.15 non-significant greater odds for a moderate/severe reaction after adjustment for age at diagnosis. CONCLUSION The incidence rate of peanut allergy increased irrespective of severity of first reaction and most children did not acquire tolerance. The majority of those diagnosed with peanut allergy were males and 0-2 years old. Peanut-specific IgE level was not associated with initial reaction severity, but was found to be a useful prognostic tool for tolerance.