Characteristics of childhood peanut allergy in the Australian Capital Territory, 1995 to 2007

Background: It is unknown whether clinical features of peanut allergy have changed in the past decade alongside possible increasing prevalence. Objective: The clinical features of peanut allergy over 13 years were examined with regard to age of onset, sex distribution, severity, and incidence. Methods: Retrospective study of 778 patients (age 4 months to 66 years) diagnosed with peanut allergy at a community-based specialist allergy practice in the Australian Capital Territory. Results: Most peanut allergy (90%) developed by age 72 months. In this group, there were no significant time-dependent changes in sex distribution, reaction severity, or age of first reaction (mean/median 12/15.1 months). Later age of first reaction was associated with an increased risk of anaphylaxis in the overall population (P < .01) and in those with onset by 72 months, in whom risk increased by 22.7% (CI, 3.3-45.7) for every additional year of age (P < .02). Asthma was associated with increased risk of anaphylaxis (odds ratio, 1.9; P < .001). In children with peanut allergy, 22% experienced anaphylaxis with first exposure and 30% with anaphylaxis had preceding milder reactions. The estimated minimum incidences of peanut allergy and sensitization by age 72 months for children born in the Australian Capital Territory in 2004 were 1.15% and 1.53%, respectively (by end December 2007), compared with 0.73% and 0.84% for those born in 2001. Conclusion: Although most characteristics of peanut allergy have changed little over the period of the last 13 years (onset age, sex, comorbidity, severity), later onset was associated with greater risk of anaphylaxis. Our data are consistent with a rise in incidence.