Association Between Earlier Introduction of Peanut and Prevalence of Peanut Allergy in Infants in Australia

To evaluate the change in prevalence of peanut allergy before and after the 2016 Australian guidelines making new recommendations for the early introduction of peanut to all infants before 12 months of age.

Two population-based, cross-sectional samples of infants aged 12 months were recruited 10 years apart using the same methodology. The original study, HealthNuts, was an Australian single center, population-based, longitudinal study designed to assess prevalence and natural history of food allergy. This study recruited 5276 infants at age 12 months from 2007 to 2011 regardless of exposure or allergy history. The comparator study, EarlyNuts, replicated the original study methodology and enrolled 1933 similar aged infants in 2018 to 2019, after the 2016 publication of early peanut introduction guideline. Some differences in demographics between the 2 studies were noted. There was a significant increase in the percentage of infants of East Asian ancestry in the later study. This is a previously documented risk factor for food allergy in Australia. Infants in the 2018 to 2019 study were more likely to have parent-reported eczema and a family history of food allergy compared with the 2007 to 2011 study.

All enrolled infants underwent skin prick testing to peanut and open oral food challenge if wheal size was equal to or greater than 1 mm. Age of peanut introduction was evaluated with a researcher-administered questionnaire. Early peanut introduction was defined as introduction of any peanut-containing product before 12 months of age. Early-onset eczema was defined as parent-reported eczema diagnosis with onset in the first 6 months of life that was managed with prescription or over the counter topical steroids. The primary outcome was peanut allergy, defined as a positive oral food challenge or a clear history of recent (within 2 months) reaction in infants with skin prick testing wheal greater than or equal to 1 mm.

Infants in the 2018 to 2019 sample (after Australian guidelines change) were introduced to peanut earlier than the 2007 to 2011 sample (85.6% vs 21.6% of participants introduced before 12 months of age). After standardizing for infant ancestry and other demographic changes, peanut allergy prevalence was not significantly different between the 2 cohorts (2.6% in 2018–2019 compared with 3.1% in 2007–2011; P = .26). In both population samples there was no significant association between the age of peanut introduction and the development of peanut allergy, except in the 2018 to 2019 sample, early peanut introduction in children of Australian ancestry (but not East Asian ancestry) was associated with lower risk of peanut allergy.

In this population-based, cross-sectional analysis, earlier introduction of peanut in infants (after guideline recommending early peanut introduction in Australia) was not associated with a statistically significant change in the prevalence of peanut allergy.

Clearly demonstrated was the successful population level change in feeding practice after the introduction of updated guidelines. Yet, the lack of a change in peanut allergy prevalence in these data suggests other factors, including earlier age of introduction, higher doses of peanut at early introduction, other risk factors for food allergy or other environmental factors, may need to be considered.