Prevalence and Clinical Impact of IgE-Mediated Food Allergy in School Children With Asthma: A Double-Blind Placebo-Controlled Food Challenge Study

PURPOSE: Recent studies indirectly suggest a possible link between food allergy (FA) and asthma. Most of them have evaluated the occurrence of FA in asthmatic children, especially in the first year of life, using questionnaire-based studies or specific IgE (sIgE) assay. The aim of this study was to evaluate the prevalence and clinical impact of IgE-mediated FA in school children with asthma using a double-blind placebo-controlled food challenge (DBPCFC). METHODS: The study group consisted of school children with atopic asthma who were admitted to the Department of Pediatric Allergology, Gastroenterology and Nutrition, Medical University of Lodz, for the evaluation of food hypersensitivity. The diagnosis of FA was established using questionnaires, sIgE analysis, and the DBPCFC. Asthma severity and asthma control state were also assessed. RESULTS: A relationship between consumed food and complaints was reported in 180 children (49.7%). Seventy children (19.3%) were sensitized to food allergens. IgE-mediated FA was confirmed in 24 children (6.6%), while 11 children (3%) demonstrated respiratory symptoms. Food-induced asthma exacerbations were observed in 9 patients (2.5%). Statistically significant differences in the prevalence of atopic dermatitis (P<0.002), urticaria (P<0.03), digestive symptoms (P<0.03), rhinitis (P<0.02), sIgE level (P<0.001), positive family history of atopy (P<0.001) and FA in history (P<0.001) were found between asthmatic children with FA and those without. Children with food-induced asthma exacerbations demonstrated significantly greater severity, poorer controls, and worse morbidity compared to those without. CONCLUSIONS: Although food-induced respiratory reactions in children with asthma were rare, they were classified as severe and associated with worse morbidity, greater severity, and poorer control. As the most commonly observed symptoms were coughing and rhinitis, which can be easily misdiagnosed, a proper diagnosis is essential for improving the management of both clinical conditions.

Use of Specific IgE and Skin Prick Test to Determine Clinical Reaction Severity.

Aims: To determine whether specific IgE and skin prick test correlate better in predicting reaction severity during a double-blinded placebo controlled food challenge (DBPCFC) for egg, milk, and multiple tree nut allergens. Study design: Prospective study. Place and Duration of Study: Department of Pediatrics, Stanford University School of Medicine, August 2009 and ongoing. Methodology: We examined the reaction severity of twenty-four subjects to nine possible food allergens: milk, egg, almond, cashew, hazelnut, peanut, sesame, pecan and walnut. Specific IgE and SPT were performed before each DBPCFC. DBPCFC results were classified into mild (1), moderate (2), or severe (3) reactions using a modified Bock’s criteria. Results: Twenty four subjects underwent a total of 80 DBPCFC. Eighty percent of all DBPCFCs resulted in a positive reaction. A majority, 71%, were classified as mild. No reactions occurred with a SPT of zero mm while three reactions occurred with a negative specific IgE. All reactions were reversible with medication. Conclusion: These data suggest that SPT and specific IgE levels are not associated with reaction severity (p<0.64 and 0.27, respectively). We also found that combining specific IgE and SPT improved specificity but did not help to achieve clinically useful sensitivity. For instance, an SPT > 5mm had a sensitivity of 91% and specificity of 50%. Combining SPT > 5mm and IgE > 7 resulted in a reduced sensitivity of 64%. Unexpectedly, a history of anaphylaxis 70% (n=17) was not predictive of anaphylaxis on challenge 4% (n=2).

Identification of IgE-mediated food allergy and allergens in older children and adults with asthma and allergic rhinitis.

Background and objective. Prevalence of immunoglobulin (Ig) E-mediated food allergy is primarily reported for certain pediatric populations and adults. The present study was aimed to investigate the relative prevalence of food allergy and allergens in older children and adults with asthma and allergic rhinitis. Methods. Patients (12-62 years) were screened using standard questionnaire and skin prick-test (SPT) with common foods and aeroallergens. Specific IgE level was determined by enzyme linked immunosorbent assay (ELISA) and allergy was established by blinded food challenges. Results. Of 1860 patients screened, 1097 (58.9%) gave history of food allergy. Of the history positive patients skin tested (n=470), 138 (29.3%) showed a marked positive reaction to food extracts. Rice elicited positive SPT reaction in maximum number of cases 29 (6.2%) followed by blackgram 28 (5.9%), lentil 26 (5.5%), citrus fruits 25 (5.3%), pea 18 (3.8%), maize 18 (3.8%) and banana 17 (3.6%). The SPT positive patients showed elevated specific IgE levels (range: 0.8-79 IU/mL) against respective food allergens than normal controls (0.73 IU/mL, mean±2SD). Food allergy was confirmed in 21/45 (46.6%) of the patients by blinded controlled food challenges. The prevalence of food allergy was estimated to be 4.5% (2.6%-6.34%) at 95% confidence interval (95% CI) in test population (n=470). Sensitisation to food was significantly associated with asthma (p=0.0065) while aeroallergens were strongly related to rhinitis (p<0.01). Conclusions. Food allergy is estimated to be 4.5% in adolescents and adults with asthma, rhinitis or both. Rice, citrus fruits, blackgram and banana are identified as major allergens for inducing allergic symptoms.

Diagnosis and Treatment of Food Allergy in Children / 소아알레르기및호흡기학회지

Food allergy is a common allergic manifestation in early childhood. However, some medical practitioners remain sceptical about the role of food allergies in a number of clinical syndromes, such as atopic dermatitis, colic and gastrooesophageal reflux in infancy, despite increasing evidences that food allergy can contribute to these conditions. Symptoms usually begin in the first 2 years of life, often after the first exposure to the known food. Diagnosis is made using medical history and can usually be detected by skin prick testing (SPT) or measuring food-specific serum IgE antibody levels. But to obtain final confirmation a double blind controlled food challenge (DBPCFC) must be performed. Delayed-onset reactions (occurring within several hours to days after ingestion) are often difficult to diagnose. The patients usually show negative SPT, so elimination or challenge protocols are required to make a definitive diagnosis. These forms of food allergy are not usually associated with anaphylaxis. Prevention and treatment are based on the avoidance of the culprit food. Children often develop tolerance to cows milk, egg, soy and wheat by school age, whereas allergies to nuts and shellfish are more likely to be lifelong. This article will help general practitioners and other clinicians understand the principles of diagnosis and management of food allergy in childhood, and suggests when to refer patients to specialist.