Background The HealthNuts study previously reported interim prevalence data showing the highest prevalence of challenge-confirmed food allergy in infants internationally. However, population-derived ...prevalence data on challenge-confirmed food allergy and other allergic diseases in preschool-aged children remain sparse. Objective This study aimed to report the updated prevalence of food allergy at age 1 year from the whole cohort, and to report the prevalence of food allergy, asthma, eczema, and allergic rhinitis at age 4 years. Methods HealthNuts is a population-based cohort study with baseline recruitment of 5276 one-year-old children who underwent skin prick test (SPT) to 4 food allergens and those with detectable SPT results had formal food challenges. At age 4 years, parents completed a questionnaire (81.3% completed) and those who previously attended the HealthNuts clinic at age 1 year or reported symptoms of a new food allergy were invited for an assessment that included SPT and oral food challenges. Data on asthma, eczema, and allergic rhinitis were captured by validated International Study of Asthma and Allergies in Childhood questionnaires. Results The prevalence of challenge-confirmed food allergy at age 1 and 4 years was 11.0% and 3.8%, respectively. At age 4 years, peanut allergy prevalence was 1.9% (95% CI, 1.6% to 2.3%), egg allergy was 1.2% (95% CI, 0.9% to 1.6%), and sesame allergy was 0.4% (95% CI, 0.3% to 0.6%). Late-onset peanut allergy at age 4 years was rare (0.2%). The prevalence of current asthma was 10.8% (95% CI, 9.7% to 12.1%), current eczema was 16.0% (95% CI, 14.7% to 17.4%), and current allergic rhinitis was 8.3% (95% CI, 7.2% to 9.4%). Forty percent to 50% of this population-based cohort experienced symptoms of an allergic disease in the first 4 years of their life. Conclusions Although the prevalence of food allergy decreased between age 1 year and age 4 years in this population-based cohort, the prevalence of any allergic disease among 4-year-old children in Melbourne, Australia, is remarkably high.
Background Several indicators suggest that food allergy in infants is common and possibly increasing. Few studies have used oral food challenge to measure this phenomenon at the population level. ...Objective To measure the prevalence of common IgE-mediated childhood food allergies in a population-based sample of 12-month-old infants by using predetermined food challenge criteria to measure outcomes. Methods A sampling frame was used to select recruitment areas to attain a representative population base. Recruitment occurred at childhood immunization sessions in Melbourne, Australia. Infants underwent skin prick testing, and those with any sensitization (wheal size ≥1 mm) to 1 or more foods (raw egg, peanut, sesame, shellfish, or cow's milk) were invited to attend an allergy research clinic. Those who registered a wheal size ≥1 mm to raw egg, peanut, or sesame underwent oral food challenge. Results Amongst 2848 infants (73% participation rate), the prevalence of any sensitization to peanut was 8.9% (95% CI, 7.9-10.0); raw egg white, 16.5% (95% CI, 15.1-17.9); sesame, 2.5% (95% CI, 2.0-3.1); cow's milk, 5.6% (95% CI, 3.2-8.0); and shellfish, 0.9% (95% CI, 0.6-1.5). The prevalence of challenge-proven peanut allergy was 3.0% (95% CI, 2.4-3.8); raw egg allergy, 8.9% (95% CI, 7.8-10.0); and sesame allergy, 0.8% (95% CI, 0.5-1.1). Oral food challenges to cow's milk and shellfish were not performed. Of those with raw egg allergy, 80.3% could tolerate baked egg. Conclusion More than 10% of 1-year-old infants had challenge-proven IgE-mediated food allergy to one of the common allergenic foods of infancy. The high prevalence of allergic disease in Australia requires further investigation and may be related to modifiable environmental factors.
Background Epidemiological evidence has shown that pediatric food allergy is more prevalent in regions further from the equator, suggesting that vitamin D insufficiency may play a role in this ...disease. Objective To investigate the role of vitamin D status in infantile food allergy. Methods A population sample of 5276 one-year-old infants underwent skin prick testing to peanut, egg, sesame, and cow’s milk or shrimp. All those with a detectable wheal and a random sample of participants with negative skin prick test results attended a hospital-based food challenge clinic. Blood samples were available for 577 infants (344 with challenge-proven food allergy, 74 sensitized but tolerant to food challenge, 159 negative on skin prick test and food challenge). Serum 25-hydroxyvitamin D levels were measured by using liquid chromatography tandem mass spectrometry. Associations between serum 25-hydroxyvitamin D and food allergy were examined by using multiple logistic regression, adjusting for potential risk and confounding factors. Results Infants of Australian-born parents, but not of parents born overseas, with vitamin D insufficiency (≤50 nmol/L) were more likely to be peanut (adjusted odds ratio aOR, 11.51; 95% CI, 2.01-65.79; P = .006) and/or egg (aOR, 3.79; 95% CI, 1.19-12.08; P = .025) allergic than were those with adequate vitamin D levels independent of eczema status. Among those with Australian-born parents, infants with vitamin D insufficiency were more likely to have multiple food allergies (≥2) rather than a single food allergy (aOR, 10.48; 95% CI, 1.60-68.61 vs aOR, 1.82; 95% CI, 0.38-8.77, respectively). Conclusions These results provide the first direct evidence that vitamin D sufficiency may be an important protective factor for food allergy in the first year of life.
Background Ninety-five percent positive predictive values (PPVs) provide an invaluable tool for clinicians to avoid unnecessary oral food challenges. However, 95% PPVs specific to infants, the age ...group most likely to present for diagnosis of food allergy, are limited. Objective We sought to develop skin prick test (SPT) and allergen-specific IgE (sIgE) thresholds with 95% PPVs for challenge-confirmed food allergy in a large population-based cohort of 1-year-old infants with challenges undertaken irrespective of SPT wheal size or previous history of ingestion. Methods HealthNuts is a population-based, longitudinal food allergy study with baseline recruitment of 1-year-old infants. Infants were recruited from council-run immunization sessions during which they underwent SPTs to 4 allergens: egg, peanut, sesame, and cow’s milk/shrimp. Any infant with a detectable SPT response was invited to undergo oral food challenge and sIgE testing. Results Five thousand two hundred seventy-six infants participated in the study. Peanut SPT responses of 8 mm or greater (95% CI, 7-9 mm), egg SPT responses of 4 mm or greater (95% CI, 3-5 mm), and sesame SPT responses of 8 mm or greater (95% CI, 5-9 mm) had 95% PPVs for challenge-proved food allergy. Peanut sIgE levels of 34 kUA /L or greater (95% CI, 14-48 kUA /L) and egg sIgE levels of 1.7 kUA /L or greater (95% CI, 1-3 kUA /L) had 95% PPVs for challenge-proved food allergy. Results were robust when stratified on established risk factors for food allergy. Egg SPT responses and sIgE levels were poor predictors of allergy to egg in baked goods. Conclusion These 95% PPVs, which were generated from a unique dataset, are valuable for the diagnosis of food allergy in young infants and were robust when stratified across a number of different risk factors.
Increasing the accuracy of peanut allergy diagnosis by using Ara h 2 Dang, Thanh D., BBiomedSc (Hons); Tang, Mimi, MBBS, PhD, FRACP, FRCPA, FAAAAI; Choo, Sharon, MBBS, FRACP, FRCPA ...
Journal of allergy and clinical immunology,
04/2012, Letnik:
129, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Background Measurement of whole peanut-specific IgE (sIgE) is often used to confirm sensitization but does not reliably predict allergy. Ara h 2 is the dominant peanut allergen detected in 90% to ...100% of patients with peanut allergy and could help improve diagnosis. Objectives We sought to determine whether Ara h 2 testing might improve the accuracy of diagnosing peanut allergy and therefore circumvent the need for an oral food challenge (OFC). Methods Infants from the population-based HealthNuts study underwent skin prick tests to determine peanut sensitization and subsequently underwent a peanut OFC to confirm allergy status. In a stratified random sample of 200 infants (100 with peanut allergy and 100 with peanut tolerance), whole peanut sIgE and Ara h 2 sIgE levels were quantified by using fluorescence enzyme immunoassay. Results By using the previously published 95% positive predictive value of 15 kUA /L for whole peanut sIgE, a corresponding specificity of 98% (95% CI, 93% to 100%) was found in this study cohort. At the equivalent specificity of 98%, the sensitivity of Ara h 2 sIgE is 60% (95% CI, 50% to 70%), correctly identifying 60% of subjects with true peanut allergy compared with only 26% correctly identified by using whole peanut sIgE. We report that when using a combined approach of plasma sIgE testing for whole peanut followed by Ara h 2 for the diagnosis of peanut allergy, the number of OFCs required is reduced by almost two thirds. Conclusion Ara h 2 plasma sIgE test levels provide higher diagnostic accuracy than whole peanut plasma sIgE levels and could be considered a new diagnostic tool to distinguish peanut allergy from peanut tolerance, which might reduce the need for an OFC.
Background There is a paucity of data examining the natural history of and risk factors for egg allergy persistence, the most common IgE-mediated food allergy in infants. Objective We aimed to assess ...the natural history of egg allergy and identify clinical predictors for persistent egg allergy in a population-based cohort. Methods The HealthNuts study is a prospective, population-based cohort study of 5276 infants who underwent skin prick tests to 4 allergens, including egg. Infants with a detectable wheal were offered hospital-based oral food challenges (OFCs) to egg, irrespective of skin prick test wheal sizes. Infants with challenge-confirmed raw egg allergy were offered baked egg OFCs at age 1 year and follow-up at age 2 years, with repeat OFCs to raw egg. Results One hundred forty infants with challenge-confirmed egg allergy at age 1 year participated in the follow-up. Egg allergy resolved in 66 (47%) infants (95% CI, 37% to 56%) by 2 years of age; however, resolution was lower in children with baked egg allergy at age 1 year compared with baked egg tolerance (13% and 56%, respectively; adjusted odds ratio, 5.27; 95% CI, 1.36-20.50; P = .02). In the subgroup of infants who were tolerant to baked egg at age 1 year, frequent ingestion of baked egg (≥5 times per month) compared with infrequent ingestion (0-4 times per month) increased the likelihood of tolerance (adjusted odds ratio, 3.52; 95% CI, 1.38-8.98; P = .009). Mutation in the filaggrin gene was not associated with the resolution of either egg allergy or egg sensitization at age 2 years. Conclusion Phenotyping of egg allergy (baked egg tolerant vs allergic) should be considered in the management of this allergy because it has prognostic implications and eases dietary restrictions. Randomized controlled trials for egg oral immunotherapy should consider stratifying at baseline by the baked egg subphenotype to account for the differential rate of tolerance development.
Background Infant feeding guidelines have long recommended delaying introduction of solids and allergenic foods to prevent allergy in high-risk infants, despite a paucity of evidence. Objective We ...aimed to determine whether confirmed egg allergy in 12-month-old infants is associated with (1) duration of breast-feeding and (2) ages of introducing egg and solids. Methods In a population-based cross-sectional study (HealthNuts) parents reported on infant feeding and potential confounding factors before skin prick testing for egg white. Egg-sensitized infants were then offered an egg oral food challenge. Multiple logistic regression was used to investigate associations between diet and egg allergy adjusted for possible confounding factors. Results A total of 2589 infants (73% response) participated. Compared with introduction at 4 to 6 months, introducing egg into the diet later was associated with higher risks of egg allergy (adjusted odds ratios ORs, 1.6 95% CI, 1.0-2.6 and 3.4 95% CI, 1.8-6.5 for introduction at 10-12 and after 12 months, respectively). These findings persisted even in children without risk factors (OR, 3.3 95% CI, 1.1-9.9; 10-12 months). At age 4 to 6 months, first exposure as cooked egg reduced the risk of egg allergy compared with first exposure as egg in baked goods (OR, 0.2 95% CI, 0.06-0.71). Duration of breast-feeding and age at introduction of solids were not associated with egg allergy. Conclusions Introduction of cooked egg at 4 to 6 months of age might protect against egg allergy. Changes in infant feeding guidelines could have a significant effect on childhood egg allergy and possibly food allergy more generally.
Background The diagnosis of food allergy (FA) can be challenging because approximately half of food-sensitized patients are asymptomatic. Current diagnostic tests are excellent makers of ...sensitization but poor predictors of clinical reactivity. Thus oral food challenges (OFCs) are required to determine a patient's risk of reactivity. Objective We sought to discover genomic biomarkers of clinical FA with utility for predicting food challenge outcomes. Methods Genome-wide DNA methylation (DNAm) profiling was performed on blood mononuclear cells from volunteers who had undergone objective OFCs, concurrent skin prick tests, and specific IgE tests. Fifty-eight food-sensitized patients (aged 11-15 months) were assessed, half of whom were clinically reactive. Thirteen nonallergic control subjects were also assessed. Reproducibility was assessed in an additional 48 samples by using methylation data from an independent population of patients with clinical FA. Results Using a supervised learning approach, we discovered a DNAm signature of 96 CpG sites that predict clinical outcomes. Diagnostic scores were derived from these 96 methylation sites, and cutoffs were determined in a sensitivity analysis. Methylation biomarkers outperformed allergen-specific IgE and skin prick tests for predicting OFC outcomes. FA status was correctly predicted in the replication cohort with an accuracy of 79.2%. Conclusion DNAm biomarkers with clinical utility for predicting food challenge outcomes are readily detectable in blood. The development of this technology in detailed follow-up studies will yield highly innovative diagnostic assays.
To the Editor: Oral food challenges (OFCs) remain the gold standard for diagnosing food allergy.1 However, to date, most studies describing the use of OFCs for the purposes of diagnosing food allergy ...have been retrospective clinical audits that have not clearly described crucial methodological characteristics, such as eligibility for challenge and exclusion and inclusion criteria.2,3 Study outcomes from these retrospective audits are difficult to generalize to other clinic or population cohorts because undeclared physician and parent selection bias is likely to significantly affect the inclusion or exclusion of, for instance, a child with a history of anaphylaxis. ...we thank ALK-Abelló, Spain, for donating food allergens for skin prick tests.
Background There are no prospectively collected data available on the natural history of peanut allergy in early childhood. Previous studies of predictors of tolerance development have been biased by ...failure to challenge high-risk children when IgE antibody levels are high, therefore potentially introducing bias to persistent allergy. Objectives We sought to describe the natural history of peanut allergy between 1 and 4 years of age and develop thresholds for skin prick test (SPT) results and specific IgE (sIgE) levels measured at age 1 and 4 years that have 95% positive predictive value (PPV) or negative predictive value for the persistence or resolution of peanut allergy. Methods One-year-old infants with challenge-confirmed peanut allergy (n = 156) from the population-based, longitudinal HealthNuts Study (n = 5276) were followed up at 4 years of age with repeat oral food challenges, SPTs, and sIgE measurements (n = 103). Challenges were undertaken in all peanut-sensitized children at 1 and 4 years of age, irrespective of risk profile. Results Peanut allergy resolved in 22% (95% CI, 14% to 31%) of children by age 4 years. Decreasing wheal size predicted tolerance, and increasing wheal size was associated with persistence. Thresholds for SPT responses and sIgE levels at age 1 year with a 95% PPV for persistent peanut allergy are an SPT-induced response of 13 mm or greater and an sIgE level of 5.0 kU/L or greater. Thresholds for SPT and sIgE results at age 4 years with a 95% PPV for persistent peanut allergy are an SPT response of 8 mm or greater and an sIgE level of 2.1 kU/L or greater. Ara h 2, tree nut, and house dust mite sensitization; coexisting food allergies; eczema; and asthma were not predictive of persistent peanut allergy. Conclusion These thresholds are the first to be generated from a unique data set in which all participants underwent oral food challenges at both diagnosis and follow-up, irrespective of SPT and sIgE results.
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