Prevalence and Cumulative Incidence of Food Hypersensitivity in the First 3 Years of Life

Venter C, Pereira B, Voigt K, et al. Allergy. 2008;63(3):354–359 PURPOSE OF THE STUDY. To investigate the prevalence and incidence of food hypersensitivity. STUDY POPULATION. The authors studied a whole population-based birth cohort of 969 children (91% of the target population) born on the Isle of Wight (United Kingdom) between 2001 and 2002. METHODS. At age 1, 2, and 3 years, all children/parents were invited to attend a clinic for a medical examination and to answer a questionnaire pertaining to food hypersensitivity (FHS), defined as any adverse reaction to food. In addition, all children were asked to participate in skin-prick testing (SPT) to milk, egg, wheat, peanut, sesame, fish, aero-allergens, and other allergens as guided by history. Children with a positive SPT result to a food that they have eaten without difficulty and children who had previous adverse reactions to specific foods were asked to undergo food challenges. With the exception of peanut and sesame, food challenges were performed after 6 months of age. Food challenges to peanut and sesame were held until the children were 3 years of age. Children with large SPT diameters considered to be >95% predictive of allergy did not undergo challenge. Frequency tables were produced at each time point, and comparisons between prevalence rates in this study and a historical reference population (Bock SA. Prospective appraisal of complaints of adverse reactions to foods in children during the first 3 years of life. Pediatrics. 1987;79[5]:683–688) was made by using Fisher's exact test. RESULTS. Over the 3-year study period, 942 (97.2%) of the children were evaluated at 1, 2, or 3 years, whereas 83.3% were seen at 1, 2, and 3 years. Sensitization rates as determined by positive SPT results at 1, 2, and 3 years were 2.2%, 3.8%, and 4.5%, respectively. Of those who were evaluated at all visits, 33.7% reported food-related problems. FHS was reported in 8.3% of those who were evaluated at their 2-year visit and 8.3% at their 3-year visit. The cumulative incidence of FHS, according to open food challenges and a clinical history, was 6% (58 of 969; 95% confidence interval [CI]: 4.6–7.7), whereas the cumulative incidence according to double-blinded, placebo-controlled food challenges was 5% (48 of 969; 95% CI: 3.7–6.5). On the basis of those with a positive open food-challenge result and clear history, the prevalence of FHS at ages 2 and 3 years was determined to be 2.5% (21 of 858; 95% CI: 1.5–3.7) and 3.0% (27 of 891; 95% CI: 2.0–4.4), respectively. Nine children who were not invited to undergo food challenges were excluded because their SPT diameter was >95% of the positive predictive value. Also, 11 and 19 of the subject's families that declined food challenges at ages 2 and 3, respectively, had histories and testing results that suggested FHS. In addition, the percentages of those diagnosed with FHS on the basis of positive food-challenge results and a clear history and were SPT-positive was 26% (age 1 year), 44% (age 2 years), and 71% (age 3 years). CONCLUSIONS. The authors reported that the cumulative incidence of FHS, according to food challenges and a clinical history, by 3 years of age was 5% to 6%. They concluded that when comparing their findings with the 1987 US study performed by Bock, there were no significant differences in the cumulative incidence of FHS. REVIEWER COMMENTS. A major strength of this study is that the authors used an unselected population that may be more representative of patients seen by pediatricians than those followed by subspecialists. Because the authors set the definition of FHS to depend on agreeing to participate and meeting criteria for participation in food challenges, the reported incidence and prevalence of true adverse reactions to food is likely to be underestimated. Additional bias could exist because many subjects did not participate in food challenges because they either had skin-testing results that suggested that they would have a clinical reaction or they had histories of recent reactions or clinical improvement with elimination of the offending food. The importance of this study is that using the authors’ very conservative definition of FHS, the reported incidence of FHS is conservatively 5% to 6%, which represents a significant pediatric health problem and underscores the need for appropriate evaluation and management of adverse reactions to food.