Prevalence and longitudinal trends of food allergy during childhood and adolescence: Results of the Isle of Wight Birth Cohort study

BackgroundThe prevalence and time trends of food allergy change during childhood depending on the age of the child and the type of food. ObjectiveTo study prevalence and longitudinal trends in food allergy from birth to 18years in an unselected birth cohort in the Isle of Wight. MethodInformation on food allergy was collected at ages 1, 2, 4, 10 and 18years from the Isle of Wight Birth Cohort (n=1456). Skin prick testing (SPT) was performed at the age of 1 and 2years in symptomatic children. At 4, 10 and 18years of age, participants were tested to a panel of food and aeroallergens. Food allergy was diagnosed based on the criteria: symptoms suggestive of a typical IgE-mediated reaction and reaction <4hours following exposure to a known food allergen. McNemar's test was used to determine significance of changes in prevalence over time. ResultsThe prevalence of food allergy remained relatively constant in early childhood (5.3%, 4.4% and 5.0% at 1, 2 and 4years, respectively), with significant decline at 10years (2.3%, P<.001 vs 4years) followed by significant rise at 18years (4%, P=.02 vs 10years). Cow's milk (1.6%-3.5%) and egg (1.1%-1.4%) were the most common allergens in the first 10years with peanut (1%) and tree nuts (0.5%) becoming more prevalent beyond 10years. Fruit and wheat allergy were less common at 10years, and shellfish and kiwi emerged during adolescence. The prevalence of food allergy plus positive SPT was 1.3%, 0.8%, 0.8%, 0.9% and 2.2% at 1, 2, 4, 10 and 18years, respectively. ConclusionFood allergy is highly prevalent in infancy with partial resolution during late childhood. However, a number of children acquire new food allergy during adolescence resulting in a relatively higher prevalence at 18years.