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Peanut Introduction, Sensitization and Allergy Development in an Unselected Canadian Cohort

      Rationale

      Delayed introduction of peanut has been shown to increase the likelihood of peanut allergy among high-risk children.

      Methods

      Caregivers of participants in the Canadian Healthy Infant Longitudinal Development (CHILD) Study prospectively reported their children’s ages of dietary introduction to peanut. At ages 1 and 3 years, the children underwent skin prick testing (SPT) to peanut and other allergens (sensitized >2 mm above saline wheal) and a clinical assessment for peanut allergy and other allergic conditions by a pediatric allergist or trained researcher. We evaluated peanut allergy diagnosis at age 3 years versus age of dietary peanut introduction before and after 1 year.

      Results

      At age 3 years, 103 children (3.85%) were sensitized to peanut; 35 (1.35%) had gained and 60 (2.32%) had lost peanut sensitization since age 1 year. Peanut allergy was diagnosed at the clinical assessment for 52 children (1.73%) and confirmed by peanut SPT (median wheal size 6.25 mm [interquartile range: 3.50-9.00, p<0.0001 versus non-allergic]). At age 3 years, 5% of children diagnosed with peanut allergy had negative peanut SPT and 1% without peanut allergy had positive peanut SPT. After adjustment for eczema and egg sensitization, children with peanut introduced after age 1 year had increased odds of peanut allergy diagnosis at 3 years (OR 2.45, 95% CI: 1.12-5.33).

      Conclusions

      In an unselected Canadian cohort, larger peanut skin prick test wheal size was strongly predictive of peanut allergy diagnosis. Children who began eating peanut after age 1 year were more likely to be diagnosed with peanut allergy at age 3 years.