Negative Food Challenge Research Articles

PRIMARY HYPERPARATHYROIDISM AS A RARE INTRINSIC CAUSE OF CHRONIC URTICARIA AND ANGIOEDEMA

<h3>Introduction</h3> Chronic urticaria and angioedema(CUA) has an incidence of approximately 0.05%,²of which autoimmune conditions contribute about 50% of the cases.³ Immune mediated Primary hyperparathyroidism, has been linked to CUA due to autoantibodies against the calcium-sensing receptors.^3,4 We present a patient with hyperparathyroidism induced CUA, who experienced four episodes of urticaria with angioedema. She was diagnosed with hyperparathyroidism after the second episode. <h3>Case Description</h3> A 70-year-old female with a history of recurrent kidney stones, Hashimoto's thyroiditis, lymphedema, SVT, osteoarthritis, and nonsmoker presented to the Emergency Department(ED) with facial and upper extremities urticaria and erythema associated with tongue swelling, dyspnea and syncope after eating crab. Since that visit, she had 3 additional episodes of urticaria and angioedema without eating crab or suspected allergens. Extensive allergy and immunology workup was negative for common CUA causes. She was prescribed Fexofenadine, Cetirizine and Famotidine daily with Epi-pen as needed. Despite this regimen, she had recurrent CUA. During the second episode, her calcium was elevated in the ED, and follow-up outpatient hyperparathyroidism workup was positive. Parathyroid scan showed an inferior right pole adenoma. She underwent partial parathyroidectomy, then experienced resolution of episodes to date and negative crab food challenge test. <h3>Discussion</h3> Primary hyperparathyroidism very rarely causes CUA through an autoimmune process. Our patient's clinical manifestations, treatment course, and improved outcomes after surgery, suggest hyperparathyroidism induced CUA. Previous reported similar presentations of primary hyperparathyroidism induced CUA resolved after partial parathyroidectomy.³ Our aim is to increase awareness of hyperparathyroidism as a potential cause of CUA and curative treatment with parathyroidectomy.

The psychological impact of food allergy and undergoing a food challenge test in adult age.

Introduction. Despite an increasing number of adults being affected by food allergy, there is currently limited research regarding the psychological impact of living with this condition in this age group and the effect of undergoing food challenge testing - the gold standard for diagnosis - on health-related quality of life (HRQoL). Objective. To assess whether ruling out a food allergy using an open food challenge could improve HRQoL and emotional well-being. To evaluate whether HRQoL gains are higher among people testing negative for food allergy and whether people higher on health anxiety would be less reassured by a negative food challenge. Methods. A cross-sectional study (n = 276) and a prospective study (n = 53) were performed. Adults with a positive (n = 34), or negative food challenge (n = 34), or with an allergy confirmed via other means (No challenge, n = 208), completed the Food Allergy Quality of Life Questionnaire-Adult Form, General Health Questionnaire-12, State-Trait Anxiety Inventory short form, Positive and Negative Affect Schedule, shortened version of the Health Anxiety Questionnaire in addition to clinical and demographic variables. A prospective study examined these measures before and three months after a food challenge (negative, n = 45; positive, n = 8). Results. Adults with a negative food challenge outcome had better HRQoL than those with a food allergy confirmed via other means (No challenge), with no differences between the two allergy positive groups (food challenge vs no challenge). No group differences in emotional distress, health anxiety or mood were found. The prospective study showed HRQoL significantly improved following a food challenge (F(1,39) = 16.868; p minor 0.001; Intention-to-treat F(1,52) = 15.346; p minor 0.001). High health anxiety was not associated with lower reassurance following a negative test. Conclusions. People who have a food allergy excluded following a food challenge have better HRQoL. There was a significant improvement in HRQoL following an open food challenge which supports the need to increase provision of food challenge testing in this age group.

Improving Successful Introduction after a Negative Food Challenge Test: How to Achieve the Best Result?

Oral food challenges (OFC) confirm or exclude the presence of a food allergy. The outcome can be positive (allergic symptoms), inconclusive, or negative (no symptoms). In the case of a negative OFC, parents and children are advised to introduce the challenged food allergen into their diet. However, previous studies showed difficulties in a successful introduction at home. The aim of this prospective non-randomized intervention study is to evaluate the effect of a new strategy with more guidance regarding the dietary introduction after a negative food challenge test. We compared two cohorts: an historical (retrospective) control group of 157 children, previously described, who did not receive any special advice after a negative OFC, versus a new cohort consisting of 104 children, who were guided according to our new strategy of written introduction schemes, food diaries, and several phone calls. In the historical control group, introduction was successful in 56%, partially successful in 16%, and 28% failed to introduce at home. After introduction of our new strategy, complete introduction was found in 82%, 11% had partially introduced, and only 8% failed to introduce the allergen. In conclusion, comprehensive advice and dietary recommendation after a negative OFC results in an increase in successful home introduction. Therefore, more attention, guidance, and follow-up of children and parents are desirable after a negative OFC.

Reactions on re-exposure following negative and inconclusive follow-up food challenges in children with acute FPIES

Reactions on re-exposure following negative and inconclusive follow-up food challenges in children with acute FPIES

Successful introduction of milk after a negative double-blind placebo-controlled food challenge test is independent of the total dose and milk product used during the challenge test.

BackgroundFailure of milk introduction after a negative food challenge test is reported in a substantial number of patients. For this reason, guidelines recommend that the total dose of milk protein for a food challenge test should be comparable to a normal serving.ObjectiveOur aim is to compare the success rate of milk introduction after a negative double‐blind placebo‐controlled challenge test performed with different doses of milk protein and different milk products.MethodsWe conducted a retrospective chart review of 485 patients challenged with a low or high dose of milk protein. Pasteurized milk and milk protein powder were used for the low‐dose challenge tests, and condensed milk for the high‐dose challenge tests. Successful introduction was defined as regular milk consumption, and discontinuation of further introduction due to the reappearance of symptoms as unsuccessful introduction. We also evaluated the association between milk products and successful introduction.ResultsThe outcome of 288 (59.4%) double‐blind placebo‐controlled food challenge tests was negative. There were no significant differences between the low and high dose of milk protein in patient characteristics, percentage of patients lost to follow‐up (15% vs 20%), in whom introduction had not yet been performed (4% vs 3.1%), reappearance of symptoms (18% vs 17%), and successful introduction (88.0% and 83.4%). Age, gender, specific immunoglobulin E for milk, dose of milk protein, and atopy were not associated with successful introduction. Children who experienced symptoms during the introduction were less likely to consume milk (P < .001). There was a nonsignificant trend toward higher successful introduction rate if pasteurized milk was used as test material compared to milk protein powder, and condensed milk.Conclusion and Clinical RelevanceSuccessful introduction of milk after a negative challenge test is independent of the total dose of milk protein, and milk product used during the challenge test.

Correlation of negative skin-prick test results for tree nuts and successful tree nut challenges among children with peanut allergy.

Background: Children with peanut allergy are regularly instructed to avoid all tree nuts. However, children with peanut allergy are likely not allergic to all tree nuts. Objective: In our cohort of patients with peanut anaphylaxis and who underwent oral immunotherapy, we sought to determine the correlation of skin-prick testing (SPT) results for tree nuts and the likelihood of successfully passing a tree nut challenge. Methods: SPT was performed for peanut and tree nuts (macadamia, pine nut, coconut, hazelnut, brazil nut, cashew, pecan, walnut, pistachio, almond) in 27 patients with known peanut allergy. The probability of a negative SPT result (wheal < 3 mm) for each nut was determined. Results: All the patients demonstrated positive results in peanut allergy diagnostics in SPT, component testing, or food challenge. Only 15.4% of the patients had a positive SPT result to peanut alone. Macadamia, pine nut, and coconut SPT had a probability of negative SPT results of 0.97, 0.97, and 0.91, respectively. The odds ratio for this group having a negative SPT was 46.22. For hazelnut, brazil nut, and cashew, the probability of a negative SPT result was 0.81, 0.77, and 0.73, respectively. Pecan, walnut, and pistachio had odds ratios of 0.68, 0.68, and 0.64, respectively. All the patients with macadamia, pine nut, and coconut negative SPT results subsequently passed 9-g food challenges without oral immunotherapy. Conclusion: Despite current recommendations to avoid all tree nuts for patients with peanut allergy, the majority of patients with peanut allergy had negative SPTs and food challenges to certain tree nuts, especially macadamia, pine nut, and coconut. This pattern was seen despite most patients having multiple nut sensitizations.

Gastrointestinal Symptoms of Food Challenge-proven Non-IgE Cow's Milk Allergy Are Dissipated by Early School Age.

The aim of this study was to evaluate the current well-being and dietary restrictions in children 6 years after food challenge-confirmed diagnosis of non-IgE cow's milk protein allergy, compared to peers with gastrointestinal symptoms but negative food challenge. This study aimed to evaluate the diagnostic process retrospectively. This is an Internet-based survey for mothers whose children underwent 6 years ago the double-blind, placebo-controlled food challenge for cow's milk (CM) because of gastrointestinal symptoms causing suspicion of non-IgE CM protein allergy. Concurrent dietary restrictions, overall well-being, medical history, and retrospective views on the food challenge were queried using a study-specific questionnaire, the Quality of life using PedsQL general score and parental stress with the Parenting Stress Index questionnaire. Mothers of 42 children (23 girls), median age of 6.7 years (range 5.7-8.6), participated in the survey, the response rate was 70%. All children now consumed cow's milk protein. The only food restrictions reported were empirical lactose-free diets in 7 children (17%). One-third of the children in both groups were presently reported to have eating-related issues such as picky eating. Quality of life was good and present parenting stress was average in both groups. The majority of the mothers (87%) felt positive or neutral about the food challenge performed in infancy. The non-IgE CM allergy with gastrointestinal symptoms diagnosed in infancy was a transient condition with good outcome. At an early school age, nearly all children have a good quality of life and a regular diet. The use of the double-blind, placebo-controlled food challenge was well-endorsed.

Rate of food introduction after a negative oral food challenge in the pediatric population

Rate of food introduction after a negative oral food challenge in the pediatric population

Failure of introduction of food allergens after negative oral food challenge tests in children.

One of the purposes to perform an oral food challenge (FC) test is to avoid unnecessary elimination of food allergens. In case of a negative FC test result, the food can be introduced. It is, however, unknown if patients act according to the outcome of the test. This study evaluates the rate of introduction of peanut, hazelnut, cow’s milk or hen’s egg allergens after a negative FC test. We investigated the introduction rate of children (0–18 years) with a negative FC test visiting the Department of Allergology, Erasmus Medical Centre Rotterdam from 2008 till 2013 and the factors that influence the rate of introduction. Patients were asked to complete a comprehensive questionnaire about their FC test. In total, 157 (38 % girls, mean age during challenge 6.9 years) participated in the study. Of these FC tests, 104 (56 %) were followed by a successful introduction, 30 (16 %) by a partly introduction (traces or processed foods) and 52 (28 %) by a failed introduction. Peanut and hazelnut showed a statistically significant lower successful introduction rate. Age, gender, symptoms during FC test, dietary advice and time period to introduction significantly influenced the rate of introduction. One fourth of the children with failure of introducing foods experienced symptoms during the introduction. Conclusion: More than one quarter of all children with a negative FC test result did not introduce the food. The FC test in its current form does not achieve its objective for this group of children. What is Known: • When the outcome of a food challenge test is negative, the food should be introduced in the diet of the child. • Failure of this introduction has negative consequences for the health of the child. What is New: • Failure of introduction of foods after a negative challenge test is reported in almost 25 % of the challenged children. • Failure of introduction after a negative challenge test is significant associated with gender, age, allergens, symptoms during OFC (according to the parents), advice, time start eating the food, and symptoms during introduction.

Safe Measles, Mumps and Rubella Vaccine Administration in Atopic Children with High Levels of Egg White-Specific IgE Antibody

Aim: To present our clinical experience vaccinating egg allergic patients with a regular triple viral vaccine. Material and Methods: Twenty seven children with atopic dermatitis and high levels of egg whitespecific IgE antibody were recruited. The patients were selected in two groups: group without history of allergic reaction to egg consumption and group with convincing history of egg allergic reaction. In children aged less than 13 months open food challenge test was performed. Results: Thirteen children without history of allergic reaction to egg received ambulatory MMR immunization with no reaction. Fourteen children with convincing history of egg allergy, aged under 13 months had not been vaccinated, and they underwent open food challenge test in the hospital. They had increased IgE specific antibodies to egg white allergen and six of them had increased specific IgE to yolk. Nine children had history of mild to moderate allergic reaction while five had severe allergic reaction. Open food challenge test was performed. Eleven children with negative food challenge test were immunized in hospital; none had an adverse reaction. Three of them had positive food challenge test and due to anxiety of the parents the immunization was dallied at age of 2 years. One of them had worsening of the eczema; the two other had no adverse reaction. Conlusion: The measles, mumps and rubella vaccine can be safely administered ambulatory to children with atopic dermatitis allergic to eggs.

Peanut Allergy: Case of an 11-Year-Old Boy with a Selective Diet

Current statistics estimate the prevalence of food allergy in the United States to be approximately 6% in children and 3% to 4% in adults ( 1 Rona R.J. Keil T. Summers C. Gislason D. Zuidmeer L. Sodergren E. Sigurdardottir S.T. Lindner T. Goldhahn K. Dahlstrom J. McBride D. Madsen C. The prevalence of food allergy: A meta-analysis. J Allergy Clin Immunol. 2007; 120: 638-646 Google Scholar ). Although eight food proteins are considered responsible for 90% of all allergic reactions (cow's milk, soybean, egg, wheat, peanut, tree nut, fish, shellfish [ 2 Hefle S.L. Nordlee J.A. Taylor S.L. Allergenic foods. Crit Rev Food Sci Nutr. 1996; 36: S69-S89 Google Scholar ]), allergy to peanut requires special consideration for several reasons ( 3 Nasser A. Shirina A. Vadas P. Peanut allergy: An overview. Allergy Asthma Clin Immunol. 2008; 4: 139-143 Google Scholar ). The age of onset of peanut allergy is young (median age of onset is approximately 24 months), and reactions are immediate and often severe. When combined with tree nut allergy, peanut allergy is responsible for the 80% of the 100 to 200 food-induced anaphylactic fatalities every year in the United States ( 4 Sicherer S.H. Sampson H.A. Peanut and tree nut allergy. Curr Opin Pediatr. 2000; 12: 567-573 Google Scholar , 5 Bock S.A. Munoz-Furlong A. Sampson H.A. Further fatalities caused by anaphylactic reactions to food, 2001-2006. J Allergy Clin Immunol. 2007; 119: 1016-1018 Google Scholar ). Sicherer and colleagues recently reported that the prevalence of peanut allergy in the United States has more than tripled between 1997 (0.4%) and 2008 (1.4% of the US population, or more than 3 million Americans) ( 6 Sicherer S.H. Muñoz-Furlong A. Godbold J.H. Sampson H.A. US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up. J Allergy Clin Immunol. 2010; 125: 1322-1326 Google Scholar ). Peanut allergy is potentially life-long, although there is evidence that approximately 20% of individuals with peanut allergy will become clinically desensitized ( 7 Fleischer D.M. The natural history of peanut and tree nut allergy. Curr Allergy Asthma Rep. 2007; 7: 175-181 Google Scholar ). It must be noted, however, that up to 8% of those who have established tolerance may become re-sensitized after a negative prick skin test (PST) and negative food challenge, especially without regular exposure to peanuts ( 8 Kerr P. Peanut resensitization after negative skin tests and negative oral challenge. J Allergy Clin Immunol. 2004; 113: S151 Google Scholar ). Of additional concern are quality-of-life issues and behavioral and emotional repercussions that can result from having a potentially life-threatening condition ( 9 Sicherer S.H. Noone S.A. Munoz-Furlong A. The impact of childhood food allergy on quality of life. Ann Allergy Asthma Immunol. 2001; 87: 461-464 Google Scholar , 10 Munoz-Furlong A. Daily coping strategies for patients and their families. Pediatrics. 2003; 111: S1654-S1661 Google Scholar ). L. S. Somers is a senior clinical pediatric nutritionist, Children's Memorial Hospital, Department of Clinical Nutrition, Chicago, IL.

Changes in diet and life of children with food allergies after a negative food challenge

Changes in diet and life of children with food allergies after a negative food challenge

Longitudinal validity and responsiveness of the Food Allergy Quality of Life Questionnaire – Parent Form in children 0–12 years following positive and negative food challenges

There are no published studies of longitudinal health-related quality of life (HRQL) assessments of food-allergic children using a disease-specific measure. This study assessed the longitudinal measurement properties of the Food Allergy Quality of Life Questionnaire - Parent Form (FAQLQ-PF) in a sample of children undergoing food challenge. Parents of children 0-12 years completed the FAQLQ-PF and the Food Allergy Independent Measure (FAIM) pre-challenge and at 2 and 6 months post food challenge. In order to evaluate longitudinal validity, differences between Group A (positive challenge) and Group B (negative challenge) were expected over time. We computed correlation coefficients between change scores in the FAQLQ-PF and change scores in the FAIM. To determine the minimally important difference (MID), we used distributional criterion and effect size approaches. A logistic regression model profiled those children falling below this point. Eighty-two children underwent a challenge (42 positive; 40 negative). Domains and total score improved significantly at pos-challenge time-points for both groups (all P<0.05). Sensitivity was demonstrated by significant differences between positive and negative groups at 6 months [F(2, 59)=6.221, P<0.003] and by differing improvement on relevant subscales (P<0.05). MID was 0.45 on a seven-point response scale. Poorer quality of life at baseline increased the odds by over 2.0 of no improvement in HRQL scores 6-month time-point. General maternal health (OR 1.252), number of foods avoided (OR 1.369) and children >9 years (OR 1.173) were also predictors. The model correctly identified 84% of cases below MID. The FAQLQ-PF is sensitive to change, and has excellent longitudinal reliability and validity in a food-allergic patient population. The standard error of measurement value of 0.5 points as a threshold for meaningful change in HRQL questionnaires was confirmed. The FAQLQ-PF may be used to identify problems in children, to assess the effectiveness of clinical trials or interventions, and to guide the development of regulatory policies.

Correlation of Initial Clinical Presentation and Egg White Specific IgE Values in a Cohort of 104 Egg Allergic Patients

Because the probability of a negative food challenge with egg correlates with the level of egg white specific IgE antibody (egg white-IgE), we investigated the correlation between initial egg white-IgE and initial clinical severity of egg hypersensitivity.

Predictive value of the sulfidoleukotriene release assay in oral allergy syndrome to celery, hazelnut, and carrot.

Patients sensitized to birch pollen frequently suffer from a food allergy to plant foods such as celery, carrots, or hazelnut. One of the main manifestations of birch pollen-related food allergy is the oral allergy syndrome. Skin tests and allergen-specific immunoglobulin (Ig) E determinations are poor predictors of such reactions when assessed by double-blind placebo-controlled food challenge (DBPCFC). To investigate whether a cellular test based on leukotriene release from basophils, the cellular antigen stimulation test in combination with enzyme-linked immunosorbent assay (CAST-ELISA), is predictive of pollen-related food allergy. Birch pollen-sensitized patients with positive DBPCFC to celery (n=21), hazelnut (n=15), and carrot (n=7) underwent skin tests along with determination of specific IgE and CAST-ELISA for the respective allergens. The results were compared with those of 24 birch pollen-sensitized patients with negative open food challenge to celery, hazelnut, and carrot. While skin prick tests had a sensitivity of 85%, 80%, and 29% for commercial extracts of celery, hazelnut, and carrot, respectively, prick testing with self-prepared extracts yielded sensitivities of 100%, 80%, and 100%, respectively. For specific IgE determinations, sensitivities were 71%, 73%, and 57%, respectively, and the respective specificities were 67%, 73%, and 60%. For CAST-ELISA with various sources and doses of allergens, the sensitivity varied from 71% to 95% for celery, 73% to 80% for hazelnut, and 43% to 86% for carrot. The respective specificities were 67% to 92%, 75% to 88%, and 77% to 91%. Analysis of the predictive value of CAST-ELISA with receiver operating characteristic curves showed that the results of the tests were more predictive of pollen-related food allergy than quantitative allergen-specific IgE determinations. CAST-ELISA is more specific than routine diagnostic tests for the diagnosis of pollen-related food allergy to celery, hazelnut, and carrot.

Facial thermography is a sensitive and specific method for assessing food challenge outcome

Oral challenge is widely used for diagnosing food allergy but variable interpretation of subjective symptoms may cause error. Facial thermography was evaluated as a novel, objective and sensitive indicator of challenge outcome. A total of 24 children with a history of egg allergy underwent oral challenge, which were scored positive when objective symptoms occurred or negative after all doses were consumed without reaction. Facial temperatures were recorded at baseline and 10-min intervals. The difference between mean and baseline temperature (DeltaT), maximum DeltaT during challenge (DeltaT(max)) and area under curve of DeltaT against time (DeltaTAUC) were calculated for predefined nasal, oral and forehead areas, and related to objective challenge outcome. There were 13 positive and 11 negative challenges. Median nasal DeltaTAUC and DeltaT(max) were greater in positive compared with negative challenges (231- and 5-fold, respectively; P < 0.05). In positive challenges, nasal temperatures showed an early transient rise at 20 min, preceding objective symptoms at median 67 min. There was a sustained temperature increase from 60 min, which was reduced by antihistamines. A cut-off for nasal DeltaT(max) of 0.8 degrees C occurring within 20 min of the start of the challenge predicted outcome with 91% sensitivity (positive predictive value [PPV] 100%) and 100% specificity (negative predictive value [NPV] 93%). Subjective symptoms occurred in four of 13 positive and three of 11 negative challenges. Facial thermography consistently detects a significant early rise in nasal temperature during positive compared with negative food challenges, which is evident before objective symptoms occur. Thermography may therefore provide a sensitive method to determine outcome of food challenges and investigate the pathophysiology of food allergic reactions.

Continuing food‐avoidance diets after negative food challenges

Negative food challenges for follow-up in patients previously diagnosed with food allergy should logically be followed by a normal diet. However, all patients do not reintroduce the food. The aims of the study were to define the proportion of negative food challenge not followed by a normal diet, and to identify possible reasons for not reintroducing the food. Patients with a negative food challenge were sent a questionnaire by mail. Items in the questionnaire included the symptoms at diagnosis, the duration of the diet, the fear of an accidental reaction during the avoidance diet and how it influenced the social life. Patients were also asked if the food was reintroduced after the negative food challenge, and if not, for which reasons. In 25.4% of the questionnaires (18/71) respondents reported that the food was not reintroduced. Patients with a previous diagnosis of peanut allergy tended to reintroduce the food less frequently than patients allergic to other foods. Girls were found to significantly less frequently reintroduce the food than boys. However, neither the severity of the initial reaction, the anxiety of an accidental reaction during the avoidance diet, nor a prolonged avoidance diet did influence the decision to reintroduce the food. Among other reasons listed, fears of persistence of allergies, with recurrent pruritus or non-specific skin rashes after eating the food, were reported in 12.7% of the total number of questionnaires. Patients who reintroduced the food reported that their social life generally improved. One quarter of previously allergic patients continue a food avoidance diet despite a negative challenge. We suggest reassessing food consumption in all patients after a negative food challenge, and in those still avoiding the specific food to consider a repeated challenge test.

Germin‐like protein Cit s 1 and profilin Cit s 2 are major allergens in orange (Citrus sinensis) fruits

Oranges are clinically relevant allergenic foods. To date, orange allergens have not been characterized in detail. The study is aimed at analyzing the sensitization profile in orange-sensitized subjects with and without clinical allergy, and to identify orange allergens. Fifty-six sensitized subjects with self-reported reactions to orange were grouped into reactors (anaphylaxis or multiple episodes of immediate reactions and/or positive challenge tests) and non-reactors (negative open food challenge tests). Allergens were characterized by IgE immunoblotting, N-terminal sequencing, IgE-inhibition assays, and mediator release assays were performed to determine the allergenic potency of orange profilin. Of 56 subjects, 23 were classified as orange allergic showing mainly an oral allergy syndrome. Of 23 subjects classified as orange allergic, 22 were sensitized to profilin, Cit s 2. In patients with mono-sensitization to profilin in vitro histamine releases up to 75% from basophils were induced using orange extract and purified plant profilins. Of the allergic patients 78% were sensitized to germin-like protein, Cit s 1. Both allergens showed retained IgE reactivity in heat-processed orange juice. Interestingly, subjects with and without clinical allergy showed a comparable sensitization profile. Profilin and germin-like proteins are major orange allergens. The potential clinical relevance of orange profilin was indicated by its strong capacity to release histamine from basophils. However, a predominant sensitization to both allergens in subjects without symptoms also indicates a high frequency of clinically insignificant sensitization.

Continuing Avoidance Diets after Negative Food Challenges

Continuing Avoidance Diets after Negative Food Challenges

Kiwi fruit is a significant allergen and is associated with differing patterns of reactivity in children and adults.

Allergy to kiwi fruit appears increasingly common, but few studies have evaluated its clinical characteristics, or evaluated methods of investigating the allergy. To characterize the clinical characteristics of kiwi fruit allergy and to study the role of double-blind placebo-controlled food challenge (DBPCFC), skin tests and specific IgE in the diagnosis of this food allergy. Two-hundred and seventy-three subjects with a history suggestive of allergy to kiwi completed a questionnaire. Forty-five were investigated by DBPCFC, prick-to-prick skin testing with fresh kiwi pulp, and specific IgE measurement. Nineteen subjects were also skin tested using a commercially available solution. The most frequently reported symptoms were localized to the oral mucosa (65%), but severe symptoms (wheeze, cyanosis or collapse) were reported by 18% of subjects. Young children were significantly more likely than adults to react on their first known exposure (P<0.001), and to report severe symptoms (P=0.008). Twenty-four of 45 subjects (53%) had allergy confirmed by DBPCFC. Prick-to-prick skin test with fresh kiwi was positive in 93% of subjects who had allergy confirmed by DBPCFC, and also in 55% of subjects with a negative food challenge. The commercial extract was significantly less sensitive, but with fewer false-positive reactions. CAP sIgE was only positive in 54% of subjects who had a positive challenge. Kiwi fruit should be considered a significant food allergen, capable of causing severe reactions, particularly in young children. DBPCFC confirmed allergy to kiwi fruit in 53% of the subjects tested, who had a previous history suggestive of kiwi allergy. Skin testing with fresh fruit has good sensitivity (93%), but poor specificity (45%) in this population. CAP sIgE and a commercially available skin test solution were both much less sensitive (54%; 75%) but had better specificity (90%; 67%).