Fleischer, D.M., 2007. The natural history of peanut and tree nut allergy. Current Allergy and Asthma Reports. 7:175–181.
Peanut and tree nut allergies were once thought to be permanent. Recent studies have shown that about 20% and 10%, respectively, of young patients may outgrow peanut and tree nut allergies. For the majority of patients, however, the natural history is not favorable. In addition, approximately 8% of patients who outgrow peanut allergy may suffer a recurrence. The rising prevalence of these allergies, coupled with the knowledge that allergic reactions to these foods have the potential to be severe or fatal and that accidental exposures are common, makes developing effective treatments to alter the natural history of peanut and tree nut allergies even more crucial for those who will not outgrow them. At this time, avoidance of the offending foods and being prepared to treat a potential reaction after accidental ingestion is the only treatment, but many promising therapeutic interventions are being investigated.
Clark, A.T., K. Anagnostou, P. W. Ewan, 2007. Cashew nut causes more severe reactions than peanut: case matched comparison in 141 children. Allergy. 62:913–916.
Background: Cashew nut allergy is becoming common, but the risk of severe reactions in comparison with peanut allergy is unknown. Method: A case-matching study of children with a recent history of a reaction after definite nut ingestion, with positive skin prick test. Children whose worst ever reaction was to cashew nut (cashew group), were matched with two children each whose worst ever reaction was to peanut (peanut group) for sex, age of reaction and presentation, amount ingested, and asthma. Severity of the worst clinical reactions to date was compared. Results: A total of 47 children in the cashew group were matched to 94 in the peanut group. There were no differences in clinical features between groups for matching criteria, except asthma (more prevalent in the peanut group). Wheezing and cardiovascular symptoms were reported more frequently during reactions in the cashew compared with the peanut group: odds ratios (OR) 8.4 (95% CI: 3.2–22.0) and 13.6 (95% CI: 5.6–32.8), respectively. The cashew group received intramuscular adrenaline more frequently: OR 13.3 (95% CI: 5.5–32.2). Overall, the OR for a severe reaction (severe dyspnoea and/or collapse) in the cashew group was 25.1 (95% CI: 3.1–203.5). Conclusions: Previous studies show cashew nut can cause severe reactions; this is the first study to show by case-matching that severe clinical reactions occur more frequently in cashew compared with peanut allergy. The nut type which caused the worst reaction to date should be considered when providing emergency medication.
Rona, R.J., T. Keil, C. Summers, D. Gislason, L. Zuidmeer, E. Sogergren, S.T. Sigurdardottir, T. Lindner, K. Goldhahn, J. Dahlstrom, D. McBride, C. Madsen, 2007. The prevalence of food allergy: a meta-analysis. Allergy Clin Immunol. 120:638-646.
Background: There is uncertainty about the prevalence of food allergy in communities. Objective: To assess the prevalence of food allergy by performing a meta-analysis according to the method of assessment used. Methods: The foods assessed were cow’s milk, hen’s egg, peanut, fish, shellfish, and an overall estimate of food allergy. We summarized the information in 5 categories: self-reported symptoms, specific IgE positive, specific skin prick test positive, symptoms combined with sensitization, and food challenge studies. We systematically searched MEDLINE and EMBASE for publications since 1990. The meta-analysis included only original studies. They were stratified by age groups: infant/preschool, school children, and adults. Results: A total of 934 articles were identified, but only 51 were considered appropriate for inclusion. The prevalence of self-reported food allergy was very high compared with objective measures. There was marked heterogeneity between studies regardless of type of assessment or food item considered, and in most analyses this persisted after age stratification. Self-reported prevalence of food allergy varied from 1.2% to 17% for milk, 0.2% to 7% for egg, 0% to 2% for peanuts and fish, 0% to 10% for shellfish, and 3% to 35% for any food. Conclusion: There is a marked heterogeneity in the prevalence of food allergy that could be a result of differences in study design or methodology, or differences between populations. Clinical implications: We recommend that measurements be made by using standardized methods, if possible food challenge. We need to be cautious in estimates of prevalence based only on self-reported food allergy.
Vlieg-Boerstra, B.J., S. van der Heide, C.M.A. Bijleveld, J. Kukler, E.J. Duiverman, S.A.A. Wolt-Plompen, A.E.J. Dubois, 2006. Dietary assessment in children adhering to a food allergen avoidance diet for allergy prevention. European Journal of Clinical Nutrition. 60:1384–1390.
Objective: The purpose of this investigation was to verify if avoidance of allergenic foods in children adhering to a food allergen avoidance diet from birth was complete and feasible, and whether dietary assessment can be used as a tool in predicting the outcome of double-blind, placebo-controlled food challenges (DBPCFCs). Design: Children adhering to an allergen avoidance diet from birth underwent DBPCFCs. The investigator-dietician verified whether the elimination was complete, using food frequency questionnaires for common allergenic foods. Setting: University Medical Centre Groningen, the Netherlands. Subjects: Thirty-eight children aged 1–13 years, who were consecutively referred to the University Medical Centre Groningen for DBPCFC between January 2002 and February 2004. Results: Among the 38 children undergoing DBPCFCs, there were 15 challenges with egg, 15 with peanut, five with hazelnut and three with soy. Fifteen food challenges (39%) were positive. Small quantities of allergenic foods were inadvertently present in the diets of 13 patients (34%), were possibly present in the diets of 14 patients (37%) and could not be identified in the diets of 11 patients (29%). Seven patients (54%) who had inadvertently ingested small quantities of allergenic foods without sequelae had a positive DBPCFC. Conclusion: Dietary avoidance was incomplete and not feasible in most cases. Tolerance of small amounts of allergenic foods does not preclude positive challenge reactions. Dietary assessment does not seem a useful tool in predicting the outcome of DBPCFC in children adhering to an elimination diet. Sponsorship: The Stichting Astma Bestrijding (Foundation for the Prevention of Asthma), The Netherlands.
