Diagnostic Work-up Of Food Allergy Research Articles

Nutritional Aspects in Diagnosis and Management of Food Hypersensitivity—The Dietitians Role

Many common foods including cow's milk, hen's egg, soya, peanut, tree nuts, fish, shellfish, and wheat may cause food allergies. The prevalence of these immune-mediated adverse reactions to foods ranges from 0.5% to 9% in different populations. In simple terms, the cornerstone of managing food allergy is to avoid consumption of foods causing symptoms and to replace them with nutritionally equivalent foods. If poorly managed, food allergy impairs quality of life more than necessary, affects normal growth in children, and causes an additional economic burden to society. Delay in diagnosis may be a further incremental factor. Thus, an increased awareness of the appropriate procedures for both diagnosis and management is of importance. This paper sets out to present principles for taking an allergy-focused diet history as part of the diagnostic work-up of food allergy. A short overview of guidelines and principles for dietary management of food allergy is discussed focusing on the nutritional management of food allergies and the particular role of the dietitian in this process.

The Effect of Hypoallergenic Diagnostic Diet in Adolescents and Adult Patients Suffering from Atopic Dermatitis

Aim:To evaluate the effect of a diagnostic hypoallergenic diet on the severity of atopic dermatitis in patients over 14 years of age.Materials and Methods:The diagnostic hypoallergenic diet was recommended to patients suffering from atopic dermatitis for a period of 3 weeks. The severity of atopic dermatitis was evaluated at the beginning and at the end of this diet (SCORAD I, SCORAD II) and the difference in the SCORAD over this period was statistically evaluated.Results:One hundred and forty-nine patients suffering from atopic dermatitis were included in the study: 108 women and 41 men. The average age of the subjects was 26.03 (SD: 9.6 years), with the ages ranging from a minimum of 14 years to a maximum of 63 years. The mean SCORAD at the beginning of the study (SCORAD I) was 32.9 points (SD: 14.1) and the mean SCORAD at the end of the diet (SCORAD II) was 25.2 points (SD: 9.99). The difference between SCORAD I and SCORAD II was evaluated with the Wilcoxon signed-rank test. The average decrease of SCORAD was 7.7 points, which was statistically significant (P=.00000).Conclusion:Introduction of the diagnostic hypoallergenic diet may serve as a temporary medical solution” in patients suffering from moderate or severe forms of atopic dermatitis. It is recommended that this diet be used in the diagnostic workup of food allergy.

Egg allergy in patients over 14 years old suffering from atopic eczema

The aim of this study was to evaluate the occurrence of egg allergy in patients over 14 years old suffering from atopic eczema and especially to evaluate if egg allergy can deteriorate the course of atopic eczema in this group of patients. Altogether 179 patients suffering from atopic eczema were included in the study: 51 men and 128 women, with an average age of 26.2 years (SD 9.5 years), with median SCORAD 31.6 (SD 13.3) points. A complete allergological and dermatological examination was performed on all patients, including diagnostic work-up of food allergy to egg [skin prick tests, atopy patch tests (APTs), measurement of specific IgE level to egg yolks or whites]. Open exposure test (OET) with egg was performed in patients with positive results in some of these diagnostic methods. Food allergy to egg was determined according to positive results in the OET or according to sufficient anamnestical data about the severe allergic reaction after the ingestion of an egg. An allergy to egg was confirmed in 11 patients out of 179 (6%). Of these patients, only six (3.3%) had a clear improvement in the SCORAD after the elimination of egg. Other triggering factors may cause exacerbation of the atopic eczema in the patients enrolled in the study. Twenty-eight percent of patients were only sensitized to egg without clinical symptoms. ATPs were a useful tool in the diagnosis of food allergy to egg in patients without IgE reactivity. Egg allergy may play an important role in the worsening of atopic eczema acting as a triggering-exacerbating factor in a minority of patients. The diagnostic work-up may comprise the challenge tests to confirm the food allergy to egg.

Comment se passer du test de provocation par voie orale en cas d’allergie alimentaire ?

Oral food challenge (OFC) is the gold standard for the diagnostic work-up of food allergy. Nevertheless, the development of new biological technique could help to determine when OFC is indicated. Contra-indications should be respected following the rules of good practice. Peptide microarray detects IgE-binding epitopes in serum, which can distinguish persistent or outgrown food allergies indicating OFC. Recombinant allergens assays are available for many foods, and represent certainly the most important tools to avoid OFC.

The Role of Atopy Patch Test in Diagnosis of Food Allergy in Atopic Eczema/Dermatitis Syndrom in Patients over 14 Years of Age

Few studies concerning the importance of food allergy in adolescents and adult patients with atopic eczema exist. The atopy patch tests with food have mostly been studied in infants and children since food allergy plays a role especially in this age group. The evaluation of the contribution of atopy patch tests in the diagnostic work-up of food allergy (to wheat, cow milk, peanuts, soya and eggs) in the patients with atopic eczema older than 14 years of age. 120 patients were examined in the study in the diagnostic work-up of food allergy--86 women and 34 men, the mean age 26.5 (s.d. 9.8) and the median SCORAD at the beginning of the study 32.9 (s.d. 14.0). Complete dermatological and allergological examinations in the diagnostic work-up of food allergy were performed (assessment of personal history, assessment of serum specific IgE, skin prick tests, atopy patch tests, diagnostic hypoallergenic diet, food challenge tests with egg, soy, wheat, cow milk and double-blind, placebo-controlled food challenge test with cow milk and wheat. The results of atopy patch tests were compared with the results of other diagnostic methods in the diagnosis of food allergy. The food allergy to cow milk and wheat was confirmed in double-blind, placebo controlled food challenge test in few patients in our study (4%). The suspicion of food allergy to egg is in 8 %, to peanuts in 13 % and to soya in 4 % of patients in our study. The assessment of atopy patch tests response seems to be of great importance. The reaction in atopy patch tests with more papules has the greatest diagnostic accuracy for predicting the result of challenge tests. At the beginning and at the end of diagnostic hypoallergenic diet the severity of atopic eczema/dermatitis syndrome was recorded in all patients enrolled in the study by evaluating SCORAD. The decrease of SCORAD was statistically important. Atopy patch tests alone cannot be used as a single test for the determination of food allergy in patients with atopic eczema/dermatitis syndrome but such a test, together with other diagnostic methods, can help to trace the food allergy.

Could food allergy testing be beneficial in adult patients with atopic dermatitis? Three case-reports

Three patients, who suffered from moderate to severe form of atopic eczema in last years, were detailed examined in the diagnostic work-up of food allergy. The examination involved measurement of specific IgE, skin prick tests, atopy patch tests with common food allergens, and challenge tests with cow milk and wheat flour (open exposure test, double-blind, placebo-controlled food challenge test). The diagnostic hypoallergenic diet was recommended to the patients. In the course of such a diet the skin finding improved. The open exposure test with cow milk or wheat flour was positive in them, the diagnosis of food allergy to cow milk and wheat flour was confirmed with double-blind, placebo-controlled food challenge test. During the first year of diet without cow milk and wheat flour the patients were checked every 3 months, SCORAD decreased and the level of SCORAD was recorded every 3 months during last 3 years also. Two patients are usually without eczematic lesions or sometimes only with solitary lesions and suffer from dry skin. One patient suffers from mild form of atopic eczema. The role of food allergy remains controversial in older children and adult patients suffering from atopic eczema. According to our result we suggest that food allergy may play a role in pathogenesis of atopic eczema in adults.

Clinical usefulness of microarray‐based IgE detection in children with suspected food allergy

Component-resolved diagnostics using microarray technology has recently been introduced into clinical allergology, but its applicability in children with food allergy has hardly been investigated so far. The aim of this study was to evaluate the utility of microarray-based IgE detection in the diagnostic workup of food allergy and to compare this new diagnostic tool with established methods of allergen-specific IgE detection. We investigated 130 infants and children with suspected allergy to cow's milk (CM) or hen's egg (HE). Serum IgE measurements, skin prick tests, allergen microarray assays and controlled oral food challenges with HE and CM were performed. We analyzed 145 oral challenges that served as reference parameters for assay performance assessment. On this basis, the panel of microarrayed allergen components was shown to represent a comprehensive repertoire of clinically relevant CM and HE proteins. Additionally, the implemented CM and HE components respectively sufficed for equivalent test performance as compared to the corresponding fluorescence enzyme immunoassay extract and skin testing. However, component-resolved diagnostics for HE and CM allergy did not make oral food challenges superfluous. Clinical IgE decision points predicting positive oral food challenges could be calculated for both in vitro test methods. Allergen microarrays provide a new tool to diagnose symptomatic CM and HE allergy. They show performance characteristics comparable to the current diagnostic tests and may be indicated in small children in whom only small blood volumes are obtainable. However, they are not capable of replacing double-blind, placebo-controlled food challenges in most cases.

Atopy Patch Test in the Diagnosis of Food Allergy in Children with Atopic Dermatitis

Atopic eczema/dermatitis syndrome (AEDS) is one of the most common chronic allergic diseases in children. Among the allergens found to be relevant in AEDS, aeroallergens and food allergens are the most important. The exposure of these patients to their relevant protein allergens can trigger an exacerbation or maintain the disease. AEDS is frequently associated with food allergy, which complicates the management in approximately 40% of these children. Atopy patch test (APT) can help in detecting food allergies in children with AEDS. The earliest publication on patch testing in eczema was described in 1937 by Rostenberg, but the first controlled clinical trial was provided by Mitchell in 1982. APT with food allergens were introduced into clinical use in 1996 by the group of Isolauri. APT test is performed epicutaneously with typical immediate-type allergens (aeroallergens or foods). As a number of apparently minor test modifications greatly influence the sensitivity, specificity, and reproducibility of the APT, the European Task Force on Atopic Dermatitis (ETFAD) has developed a standardized APT technique. APT has developed into a valuable additional tool in the diagnostic work-up of food allergy in infants and children with atopic dermatitis.

The predictive value of the skin prick test weal size for the outcome of oral food challenges

The skin prick test (SPT) is regarded as an important diagnostic measure in the diagnostic work-up of food allergy. Objective To evaluate the diagnostic capacity of the SPT in predicting the outcome of oral food challenges, and to determine decision points for the weal size and the skin index (SI) that could render double-blind, placebo-controlled food challenges unnecessary. In 385 children (median age 22 months), 735 controlled oral challenges were performed with cow's milk (CM), hen's egg (HE), wheat and soy. Three hundred and thirty-six of 385 (87%) children suffered from atopic dermatitis. SPT was performed in all children. Diagnostic capacity, receiver-operator characteristics (ROC) curves and predictive decision points were calculated for the mean weal size and the calculated SI. Three hundred and twelve of 735 (43%) oral food challenges were assessed to be positive. Calculation of 95% and 99% predicted probabilities using logistic regression revealed predictive decision points of 13.0 and 17.8 mm for HE, and 12.5 and 17.3 mm for CM, respectively. However, using the SI, the corresponding cut-off levels were 2.6 and 3.7, respectively, for HE, and 2.7 and 3.7 for CM. For wheat, 95% and 99% decision points of 2.2 and 3.0 were found in children below 1 year of age. Predictive decision points for a positive outcome of food challenges can be calculated for HE and CM using weal size and SI. They may help to avoid oral food challenges.

Oral food challenges in children in Italy

Epidemiological surveys identify a 900,000-strong potential paediatric population who may self-report with food allergy in Italy. As the reference test is the double-blind, placebo-controlled food challenge for diagnosis, we carried out a nation-wide questionnaire survey of hospital-based paediatric allergy centres between 1 January and 30 June 2003. All registered centres received a 27-point questionnaire polling logistics and protocols of oral food challenge. Items polled included medical facilities and personnel, selection of patients, foods tested, blinding, placebo use, evaluation criteria, number of tests and positive outcome rates in 2002. Two hundred and two of 456 responders (44.3%) carried out food challenges (a ratio of one centre to 37,400 children in the general population). 11,728 challenges were performed in 2002 (an average of 58 procedures per centre; range: 1-500) and 3350 procedures were claimed positive (28.6%). Cow's milk was tested by all centres, egg by 77.2%, beef by 19.8% and cereals, peanuts, fish or fruit collectively by 37.6%. Twenty-nine of 202 centres performed blinded tests, 18 of which under double-blinded conditions. In cow's milk challenges, placebos included lyophilized cow's milk capsules, soy formula, extensive whey hydrolysate or extensive casein hydrolysate. Our survey reveals great differences in challenge test criteria, facilities and procedures and that many centres perform relatively few procedures. This argues in favour of greater rationalization in the allocation of tertiary-level resources before procedure standardization can be contemplated in the diagnostic workup of food allergy.

The predictive value of specific immunoglobulin E levels in serum for the outcome of oral food challenges

Specific serum IgE is considered as one of the important diagnostic measures in the diagnostic work-up of food allergy. To evaluate the role of specific serum IgE in predicting the outcome of oral food challenges, and to determine threshold concentrations of specific serum IgE that could render double-blind, placebo-controlled food challenges unnecessary. In 501 children (median age 13 months), 992 controlled oral challenges were performed with cow's milk (CM), hen's egg (HE), wheat and soy. 440/501 (88%) children suffered from atopic dermatitis. For all children, specific IgE concentrations in serum were determined. Sensitivity, specificity, positive and negative predictive values, receiver operator characteristics-curves as well as predictive decision points were calculated. Four hundred and forty-five out of 992 oral food challenges with allergens were assessed as positive. Sensitivity of specific serum IgE was 97% for HE, 83% for CM, 69% for soy, and 79% for wheat. Specificity was 51% for HE, 53% for CM, 50% for soy, and 38% for wheat. Calculating 90%, 95% and 99% predicted probabilities using logistic regression revealed predictive decision points of 6.3, 12.6, and 59.2 kU/L for HE, respectively. Subdividing our children in those of below or above 1 year of age resulted in a markedly different predicted probability for HE. For CM, only the 90% predicted probability (88.8 kU/L) could be calculated. No decision points could be determined for CM, wheat and soy. In general, specific serum IgE levels showed a correlation with the outcome of positive oral food challenges for CM and HE. Meaningful predictive decision points can be calculated for HE, which may help to avoid oral food challenges in some cases. However, data need to be ascertained for each allergen separately. Furthermore, the age of the patient population under investigation must also be taken into account.

Diagnostic pitfalls in food allergy in children

Currently, the diagnostic work-up of suspected food allergy includes skin prick tests, the measurement of food specific immunoglobulin E (IgE), and the atopy patch test, and double-blind, placebo-controlled food challenges. However, all of these methods, even double-blind, placebo-controlled food challenges (DBPCFC), may sometimes be misleading. This overview describes several pitfalls for standard diagnostic methods such as problems with irritative skin reactions mimicking IgE-mediated symptoms, the problem of non-IgE-mediated reactions, pitfalls arising from the way foods are prepared or processed, effects of the route of exposure, the role of augmentation factors lowering the threshold value for clinical reactions, the noncomparability of specific IgE decision points, the influence of the timing of diagnostic measures. In addition, the problem of alternative diagnostic measures is discussed. In conclusion, there are several pitfalls in the diagnostic work-up of food allergy, which may be misleading for the physician. Properly performed controlled oral food challenges still represent the gold standard for implementing specific diets in food allergic individuals in order to avoid both unjustified diets, which may lead to severe impairments in growth and development, and to avoid unnecessary symptoms if an underlying food allergy is not correctly identified as a cause for the symptoms of the patient.

The diagnostic value of atopy patch test (APT) with regard to late-phase clinical reactions to food in children with atopic dermatitis (AD)

Rationale Non IgE-mediated adverse responses to food tent to involve a T-cell mediated delayed hypersensitivity reaction that can be evaluated by the APT. The aim was to evaluate the diagnostic value of the APT with regard to late-phase reactions observed in double blind, placebo-controlled food challenges (DBPCFCs) with cow's milk, hen's egg, wheat, in children with AD. Methods One hundred and thirteen children [69 males, median age 4.2 years (range 4 months-12.7 years)] suffering from AD and suspected food-related clinical symptoms were investigated with APT and DBPCFCs. Results We found that late-phase clinical reactions to food observed in DBPCFCs were associated with a positive APT; the sensitivity to cow's milk was 64%, to hen's egg 86%, to wheat 100%; the specificity was 86% for milk, 73% for egg and 95% for wheat; positive predictive value was 47% for milk, 22% for egg, 40% for wheat; negative predictive values were 93%, 98% and 100% respectively. Of 229 DBPCFCs, 24 (40%) were assessed as positive for cow's milk, 32 (53%) for hen's egg, 4 (7%) for wheat. Out of 42 patients with APT positive reactions, 20 (53.8%) had positive response to hen's egg, 4 (10.8%) to milk, 4 (10.8%) to wheat, 12 (32.3%) to milk and egg, 2 (5.4%) to milk and wheat. Conclusions Our findings confirm that the APT may be a valuable additional tool in the diagnostic work-up of food allergy in children with AD because of its high specificity and sensibility for late-phase clinical reactions; however DBPCFC must be still considered the diagnostic gold standard test.

Influence of Age on the Outcome of the Atopy Patch Test with Food in Children with Atopic Dermatitis

Influence of Age on the Outcome of the Atopy Patch Test with Food in Children with Atopic Dermatitis

Evolving role of the atopy patch test in the diagnosis of food allergy.

The atopy patch test has developed into a valuable additional tool in the diagnostic work-up of food allergy in infants and children with atopic dermatitis. A positive atopy patch test may help to prevent imposing restrictive and unnecessary diets after misjudging late reactions by clinical assessment alone. Furthermore, the combination of positive atopy patch tests together with defined levels of specific IgE makes double-blind, placebo-controlled food challenges superfluous in some cases. However, several open questions indicate the need for further studies.

Atopy Patch Test (APT)--its role in diagnosis of food allergy in atopic dermatitis.

During the past few years, the Atopy Patch Test (APT) has become a valuable additional tool in the diagnostic work-up of food allergy in infants and children with atopic dermatitis. A positive APT may help to prevent restrictive and unnecessary diets which may be the consequence of misjudging late reactions by clinical assessment alone. Furthermore, the combination of positive atopy patch tests together with defined levels of specific IgE (cow milk = 0.35 kU/l and egg = 17.5 kU/l) makes DBPCFC superfluous for suspected milk and egg allergy. However, several open questions indicate the need for further studies.

The atopy patch test (APT) – a useful tool for the diagnosis of food allergy in children with atopic dermatitis

While immediate-type clinical reactions to food can quite easily be identified by history or measurement of specific IgE in combination with positive oral food challenges, the evaluation of food allergy in the absence of immediate clinical reactions still presents diagnostic difficulties--particularly in children with atopic dermatitis. The objective of this study was to evaluate the diagnostic value of the atopy patch test (APT) with regard to late-phase reactions observed in double-blind, placebo-controlled food challenges with cow's milk, hen's egg, wheat, and soybean. We investigated 75 children (median age 2.1 years) with suspected food allergy by double-blind, placebo-controlled food challenges, specific IgE in serum, skin prick test, and APT. Of the subjects, 69/75 suffered from atopic dermatitis. Of 209 oral challenges, 133 were performed with allergen and 76 with placebo. We assessed 77/133 allergen and 2/76 placebo challenges as positive. In 66 of 77 (86%) positive oral challenges, specific IgE in serum to the corresponding allergen was positive; in 64/77 (83%) the skin prick test, and in 42/77 (55%) the APT was positive. While immediate-type reactions were associated with positive skin prick test and proof of specific IgE in serum, late-phase clinical reactions were associated with a positive APT (sensitivity 76%, specificity 95%). The APT seems to be a valuable additional tool in the diagnostic work-up of food allergy in children with atopic dermatitis - especially with regard to late-phase clinical reactions. The APT may help to prevent unnecessary restrictive diets which may be the consequence of misjudging late reactions by clinical assessment alone.