Agreement of specific IgE and skin prick test in an unselected cohort of two-year-old children

The Importance of Nasal Provocation Testing in the Diagnosis of Dermatophagoides pteronyssinus-Induced Allergic Rhinitis

BACKGROUND

Allergen identification is the first step for allergen-specific immunotherapy (AIT) of allergic rhinitis (AR). Currently, the diagnosis of AR is based mainly on the positive results of the skin prick test (SPT) and/or serum specific immunoglobulin E (sIgE) measurement. However, the results of these two tests may not always directly correlate with AR.

OBJECTIVE

To investigate the importance of nasal provocation testing (NPT) in the diagnosis of Dermatophagoides pteronyssinus (Der p)-induced AR.

METHODS

Rhinitis patients willing to undergo AIT (n = 171) were enrolled. The correlations of Der p SPT, sIgE, NPT, and clinical symptom severity were assessed.

RESULTS

NPT-positive responses were more common in patients with higher SPT and sIgE levels. The optimal cut-off value for a NPT-positive response for SPT was 5.5 mm and for sIgE was 2.77 kUA/L, based on the respective receiver operating characteristic (ROC) curves. The area under the curve (AUC) of the ROCs was 0.814 (SPT only) and 0.794 (sIgE only) and increased to 0.828 with the combination of SPT and sIgE. The Der p-NPT concentration was inversely correlated with SPT and sIgE levels (r = -0.477, P < .001, and r = -0.461, P < .001, respectively), but none was correlated with the total nasal symptom score.

CONCLUSION

For patients who are willing to receive Der p AIT, NPT is a useful and safe test to confirm diagnosis prior to treatment initiation, especially in patients with lower levels of Der p SPT (< 5.5 mm) or sIgE (< 2.77 kUA/L).

Allergy-Related Symptoms Are Poorly Predicted by IgE and Skin Prick Testing in Early Life

INTRODUCTION

In childhood, the so-called allergic march involves progression from IgE sensitization to allergy-related symptoms. Both IgE sensitization and relevant clinical symptoms are required for the diagnosis of allergy, but concordance between test results and clinical symptoms varies greatly, creating challenges for the diagnostics and for the prediction of outcomes. We assessed the prevalence of IgE sensitization and allergy symptoms, concordance between 2 IgE sensitization testing methods, and predictive value of these tests in relation to clinical symptoms in young Finnish children.

METHODS

The current study included 2 series of children: a birth cohort, in which the participants were followed prospectively from birth up to 3 years, and a young children cohort observed from 3 to 5 years of age. They were regularly monitored for sensitization by measuring serum allergen-specific IgEs (sIgEs) and performing skin prick tests (SPTs). The emergence of atopic dermatitis, wheezing, and symptoms associated with food allergies was recorded.

RESULTS

Over the first 5 years of life, the prevalence of sIgE sensitization was 46%, while it was 36% for positive SPTs. Disease prevalence was 26% for atopic dermatitis, 25% for wheezing, and 19% for symptoms associated with food allergies. Concordance between sIgE and SPT results was good for aeroallergens, but poor for dietary allergens. The association between clinical symptoms and sensitization was stronger at 5 years than at 3 years of age. The proportion of children with concordant combinations of allergy symptoms and sensitization markers in contrast to those with discordant combinations increased from 3 to 5 years.

CONCLUSION

In early childhood, testing for IgE sensitization predicts allergy-related symptoms in an age-dependent manner, but not particularly well. Tests predict symptoms caused by aeroallergens clearly better than those caused by dietary allergens. The clinical relevance of sensitization testing in early life is therefore limited in the prediction of true allergy.

Can evaluation of specific immunoglobulin E serum concentrations of antibodies to aeroallergens in atopic dermatitis patients replace skin prick tests method in clinical practice?

Introduction

Positive skin prick tests (SPT) results with protein allergens are the minor Hanifin and Rajka's atopic dermatitis (AD) criterion. In adults, they mainly concern aeroallergens. The inflammation of skin often prevents SPT, but does not exclude the assessment of serous specific immunoglobulin E (sIgE) concentrations.

Aim

To assess usefulness of testing AD patients to aeroallergens with SPT and sIgE concentrations, and the correlation of these results and the clinical AD course.

Material and methods

In 286 AD patients, total IgE and sIgE (14 aeroallergens) were measured. SPTs were performed with 17 aeroallergens. The AD severity was determined depending on the concurrent co-existence of asthma, allergic rhinitis, extensive skin flares and severe itching.

Results

59.1% and 66.1% of patients have had positive results of sIgE and SPT, respectively (p > 0.05). The concentration of total IgE has positively correlated with the number of positive sIgE results (rho = 0.588, p < 0.001) and their intensity (rho = 0.592, p < 0.001). Among the patients with at least one high positive sIgE score, severe AD patients have been dominant (59.8% vs. 40.2%, p < 0.04). Among the patients with positive results without any high scores, the percentages are 21.6 and 78.4, respectively (p < 0.001).

Conclusions

The compatibility of SPT results and IgE concentrations indicates that the two methods equally assess aeroallergy in AD patients. The assessment of sIgE concentrations is especially advisable in patients with an elevated total IgE level. The obtained results may suggest that presence of a high specific IgE level of antibodies to aeroallergens may be the factor predicting a severe clinical AD course.

Skin prick tests and specific IgE in 10-year-old children: Agreement and association with allergic diseases

BACKGROUND

Accurate assessment of atopic sensitization is pivotal to clinical practice and research. Skin prick test (SPT) and specific IgE (sIgE) are often used interchangeably. Some studies have suggested a disagreement between these two methods, and little is known about their association with allergic diseases. The aims of our study were to evaluate agreement between SPT and sIgE, and to compare their association with allergic diseases in 10-year-old children.

METHODS

Skin prick test, sIgE measurements, and assessment of allergic diseases were performed in children aged 10 years in the Protection against Allergy: STUdy in Rural Environments (PASTURE) cohort. The agreement between SPT and sIgE was assessed by Cohen's kappa coefficient with different cutoff values.

RESULTS

Skin prick tests and sIgE were performed in 529 children. The highest agreement (κ=.44) was found with a cutoff value of 3 and 5 mm for SPT, and 3.5 IU/mL for sIgE. The area under the curve (AUC) obtained with SPT was not significantly different from that obtained with sIgE. For asthma and hay fever, SPT (cutoff value at 3 mm) had a significantly higher specificity (P<.0001) than sIgE (cutoff value at 0.35 IU/mL) and the specificity was not different between both tests (P=.1088).

CONCLUSION

Skin prick test and sIgE display moderate agreement, but have a similar AUC for allergic diseases. At the cutoff value of 3 mm for SPT and 0.35 IU/mL for sIgE, SPT has a higher specificity for asthma and hay fever than sIgE without difference for sensitivity.

Prevalence of fish and shellfish allergy: A systematic review

BACKGROUND

Accurate information on the prevalence of food allergy facilitates a more evidence-based approach to planning of allergy services and can identify important geographic variations.

OBJECTIVE

To conduct a systematic review to assess the age-specific prevalence of fish and shellfish allergy worldwide.

METHODS

Searches were conducted using Web of Science and PubMed. Population-based cross-sectional studies and cohort studies that examined the prevalence of fish and shellfish allergy (IgE mediated and non-IgE mediated) at an identifiable point in time were eligible for inclusion in the study. Reviewers extracted general study information and study design, type of food allergy considered, food(s) assessed, method of diagnosis, sampling strategy, and sample characteristics. Raw data were extracted and percentage prevalence and 95% confidence intervals calculated.

RESULTS

A total of 7,333 articles were identified of which 61 studies met the inclusion criteria and were included in this review. The prevalence of fish allergy ranged from 0% to 7% and the prevalence of shellfish allergy from 0% to 10.3%, depending on the method of diagnosis. Where food challenges were used, the prevalence for fish allergy was found to be 0% to 0.3% and for shellfish allergy was 0% to 0.9%.

CONCLUSION

Few studies have established the prevalence of fish or shellfish allergy using the gold standard double-blind, placebo-controlled challenge criteria, with most instead relying on self-reported questionnaire-based methods. The limited data available suggest that fish allergy prevalence is similar worldwide; however, shellfish allergy prevalence may be higher in the Southeast Asia region.

Conjunctival allergen provocation test : guidelines for daily practice

Conjunctival allergen provocation test (CAPT) reproduces the events occurring by instilling an allergen on the ocular surface. This paper is the compilation of a task force focussed on practical aspects of this technique based on the analysis of 131 papers. Main mechanisms involved are reviewed. Indications are diagnosing the allergen(s)-triggering symptoms in IgE-mediated ocular allergy in seasonal, acute or perennial forms of allergic conjunctivitis, especially when the relevance of the allergen is not obvious or in polysensitized patients. Contraindications are limited to ongoing systemic severe pathology, asthma and eye diseases. CAPT should be delayed if receiving systemic steroids or antihistamines. Local treatment should be interrupted according to the half-life of each drug. Prerequisites are as follows: obtaining informed consent; evidencing of an allergen by skin prick tests and/or serum-specific IgE dosages; being able to deal with an unlikely event such as acute asthma exacerbation, urticaria or anaphylaxis, or an exacerbation of allergic conjunctivitis. Allergen extracts should be diluted locally prior to administration. Positive criteria are based on itching or quoted according to a composite score. An alternative scoring is based on itching. CAPT remains underused in daily practice, although it is a safe and simple procedure which can provide valuable clinical information.

Evidence in immunotherapy for paediatric respiratory allergy: Advances and recommendations

Allergic respiratory diseases are major health problems in paediatric population due their high level of prevalence and chronicity, and to their relevance in the costs and quality of life. One of the most important risk factors for the development of airway diseases in children and adolescents is atopy. The mainstays for the treatment of these diseases are avoiding allergens, controlling symptoms, and preventing them through sustained desensitization by allergen immunotherapy (AIT). AIT is a treatment option that consists in the administration of increasing amounts of allergens to modify the biological response to them, inducing long-term tolerance even after treatment has ended. This treatment approach has shown to decrease symptoms and improve quality of life, becoming cost effective for a large number of patients. In addition, it is considered the only treatment that can influence the natural course of the disease by targeting the cause of the allergic inflammatory response. The aim of this publication is to reflect the advances of AIT in the diagnosis and treatment of allergic respiratory diseases in children and adolescents reviewing articles published since 2000, establishing evidence categories to support the strength of the recommendations based on evidence. The first part of the article covers the prerequisite issues to understand how AIT is effective, such as the correct etiologic and clinical diagnosis of allergic respiratory diseases. Following this, the article outlines the advancements in understanding the mechanisms by which AIT achieve immune tolerance to allergens. Administration routes, treatment regimens, dose and duration, efficacy, safety, and factors associated with adherence are also reviewed. Finally, the article reviews future advances in the research of AIT.

Atopic endotype in childhood

BACKGROUND

The term atopic disorder is an early attempt to define specific endotypes of children with asthma, eczema, or both and increased IgE levels.

OBJECTIVE

We performed a longitudinal analysis of the relevance of the atopic endotype from birth to age 13 years.

METHODS

Allergic sensitization against 28 inhalant and food allergens was assessed at ½, 1½, 4, 6, and 13 years of age in 399 children from the Copenhagen Prospective Study on Asthma in Childhood2000 birth cohort by using both skin prick test responses and specific IgE levels. Asthma and eczema were diagnosed longitudinally by strictly adhering to predefined algorithms. Associations between allergic sensitization, asthma, and eczema were estimated by means of logistic regression, and a machine learning approach was used to identify temporal phenotype clusters of these traits.

RESULTS

Allergic sensitization showed no association with asthma through early childhood (0-6 years) when analyzed as any sensitization (odds ratio [OR] range, 0.78-1.29; P ≥ .48). However, at 13 years of age, any sensitization was associated with asthma (OR range, 4.02-5.94; all P < .001). In contrast, any sensitization was associated with eczema at ½, 1½, and 6 years of age (OR range, 2.06-6.02; P ≤ .01) and borderline associated at 4 years of age (OR, 1.61 [95% CI, 0.96-2.69]; P = .07) but not at 13 years of age (OR, 1.57 [95% CI, 0.78-3.16]; P = .21). We identified 4 latent patterns of disease development that were either dominated by sensitization (37%), eczema (26%), asthma (14%), or healthy status (24%).

CONCLUSION

We found very little interdependency between asthma, eczema, and allergic sensitization through childhood. The associations between those entities were strongly dependent on age, type of allergens, and method of testing for sensitization. Therefore, atopy in children is unlikely to represent a true endotype.

Breast-feeding does not protect against allergic sensitization in early childhood and allergy-associated disease at age 7 years

BACKGROUND

Extended breast-feeding is recommended for newborn children at risk of allergy-associated diseases, but the evidence of a protective effect on sensitization and these diseases remains elusive.

OBJECTIVE

The aim of this study was to investigate the effects of the duration of exclusive breast-feeding on the development of sensitization in preschool children.

METHODS

Information on breast-feeding was gathered by interviews involving 335 children aged 1, 6, and 12 months from the Copenhagen Prospective Study on Asthma in Childhood2000 birth cohort born to mothers with a history of asthma. Skin prick test responses and specific IgE levels against 12 common inhalant and 10 food allergens were assessed longitudinally at ages ½ year, 1½ years, 4 years, and 6 years. Eczema, wheeze/asthma, and allergic rhinitis were diagnosed at the Copenhagen Prospective Studies on Asthma in Childhood clinic at 7 years of age, strictly adhering to predefined algorithms. Associations between duration of exclusive breast-feeding and outcomes were analyzed by logistic regression.

RESULTS

We found no significant association between duration of exclusive breast-feeding and development of sensitization in the first 6 years of life (odds ratio [OR]: ½ year, 1.10 [95% CI, 0.90-1.36]; 1½ years, 1.15 [95% CI, 0.97-1.36]; 4 years, 1.08 [95% CI, 0.93-1.25]; and 6 years, 0.96 [95% CI, 0.84-1.10]) or with current eczema, wheeze/asthma, and allergic rhinitis at age 7 years (OR, 1.07 [95% CI, 0.92-1.24]; OR, 0.97 [95% CI, 0.82-1.14]; and OR, 1.02 [95% CI, 0.84-1.23], respectively). Adjusting for reverse causation by excluding children with eczema, wheeze, or a positive skin prick test response before ending exclusive breast-feeding did not alter the results.

CONCLUSION

Exclusive breast-feeding does not affect sensitization in early childhood or associated diseases at 7 years of age in at-risk children.

Disagreement between skin prick test and specific IgE in young children

BACKGROUND

Skin prick test (SPT) and measurement of serum-specific IgE (sIgE) level are important tools for the clinician to diagnose allergic sensitization. However, little is known about the agreement between the two methods in young children.

METHODS

SPT and sIgE levels were assessed simultaneously for 16 common inhalant and food allergens at age ½, 1½, 4, and 6 years in 389 children from the Copenhagen Prospective Study on Asthma in Childhood2000 (COPSAC2000 ) at-risk birth cohort. Agreement between the two methods for diagnosing inhalant and food allergic sensitization at the four age points was analyzed using kappa statistics.

RESULTS

The prevalence of inhalant allergen sensitization increased during childhood diagnosed by both sIgE levels (0.6% to 4.2% to 18.1% to 24.8%, P < 0.0001) and SPT results (1.5% to 3.8% to 8.4% to 15.4%, P < 0.0001). In contrast, the prevalence of food sensitization increased during childhood when diagnosed from sIgE (7.8% to 12.1% to 15.0% to 18.9%, P < 0.0001), but decreased when diagnosed from SPT (5.3% to 5.1% to 3.7% to 3.0%, P = 0.05). Overall, the agreement between SPT and sIgE levels was poor to moderate (all κ-coefficients ≤ 0.60) and decreased from moderate to slight for food allergens by increasing age (κ-coefficients: 0.46 to 0.31 to 0.16 to 0.14).

CONCLUSION

There is a substantial disagreement between SPT and sIgE for diagnosing allergic sensitization in young children, which increases with age for food sensitization. Choice of assessment method therefore has major impact on results with wide implications for both clinical practice and research.

The predictive value of allergen skin prick tests and IgE tests at pre-school age: the PACT study

BACKGROUND

Sensitization toward allergens, as determined by skin prick test (SPT) or specific IgE (sIgE), is a predictor for the later presence of allergy-related disease (atopic eczema, allergic rhinoconjuctivitis and asthma). However, it is not known whether SPT or sIgE should be the preferred test. The aim of this study was to compare the predictive ability of SPT and sIgE when performed in a general population of 2-yr-old children.

METHODS

In a prospective, longitudinal population-based study of children aged 2-6 yr, SPT and sIgE for nine common allergens were performed at 2 yr. Allergy-related disease was evaluated by clinical examination and questionnaire at 2 and 6 yr of age (n = 199).

RESULTS

Skin prick test or sIgE was positive in 10.6% and 21.1% in the 2-yr-old children, respectively. The prevalence of allergy-related disease was 25.6% at 2 yr and 25.1% at 6 yr. Half of the cases at 2 yr were transient. Both SPT and sIgE were statistically significant predictors for later allergy-related disease, OR = 6.5 (95% CI 2.3-18.6) and OR = 4.1 (95% CI 1.9-9.0), respectively. Receiver operating characteristic analysis showed that SPT and sIgE had comparable predictive ability for atopic eczema, asthma or any allergy-related disease, but sIgE had better ability to predict later allergic rhinoconjunctivitis.

CONCLUSION

Sensitization at 2 yr may be useful predictors of allergy-related disease later in childhood. The predictive ability of SPT and sIgE were mainly comparable; however, it may be that sIgE is the preferred choice in young children when the aim is to predict allergic rhinoconjunctivitis.

Agreement between the skin prick test and specific serum IgE for egg white and cow's milk allergens in young infant with atopic dermatitis

BACKGROUND

The skin prick test (SPT) for detecting atopic sensitization is not preferred in young infants with atopic dermatitis (AD) because of concerns about poor skin reactivity. This study aimed to evaluate whether the results of SPT agreed well with those of specific serum immunoglobulin E (sIgE) antibody test in young infants with AD.

METHODS

This study included 2,077 eligible infants (age, <12 months) with AD who were tested by either SPT or sIgE between 2007 and 2011. Among them, 199 infants tested for egg white (EW) and 192 infants tested for cow's milk (CM), by both SPT and sIgE on the same day were identified and reviewed retrospectively. Kappa statistics and tests for equal kappa statistics were used to evaluate the agreement between the SPT and sIgE.

RESULTS

The mean wheal diameter and the allergen-to-histamine ratio of SPT showed substantial agreement with those of sIgE for EW (κ = 0.62, 0.69) and CM (κ = 0.34, 0.47). The agreement for EW was significantly higher <6-month-old than in ≥6-month-old infants (κ = 0.79 vs. 0.54, P = 0.02), and that for CM was similar (P = 0.60). The mean wheal diameters for EW and CM were evenly distributed, and did not show increasing trends regardless of age in months (Ptrend = 0.13 and 0.06, respectively).

CONCLUSIONS

The results of SPT agreed well with those of sIgE. This finding provides a rationale for using SPT, and suggests that SPT can be used along with sIgE to detect food sensitization in young infants with AD.

The value of mucosal allergen challenge for the diagnosis of food allergy

PURPOSE OF REVIEW

The incidence of food allergy is increasing. Correct diagnosis is dependent on food challenges, which are not always performed, but more often based on history, skin prick test and specific IgE, leading to possible misdiagnoses. Mucosal provocation tests have been proposed as possible new diagnostic tools during recent decades.

RECENT FINDINGS

The databases EMBASE, PUBMED and Cochraine Review were used. Seven full text articles fulfilled criteria for mucosal challenge and food allergy, only one from the last 12 months. Conjunctival, nasal, buccal, gastric and coecal/rectal mucosa have been challenged. All authors find mucosal changes after challenge, but the lack of validation against double-blind placebo-controlled challenges makes evaluation difficult, with the exception of the conjunctival provocation test.

SUMMARY

As most mucosal surfaces are easily available, and small amounts of allergen are needed for an obvious reaction, this tool for diagnosing food allergy is promising. Further studies are however needed.

Role of exhaled nitric oxide as a predictor of atopy

BACKGROUND

The fractional exhaled nitric oxide (FeNO) is a quantitative, noninvasive and safe measure of airways inflammation that may complement the assessment of asthma. Elevations of FeNO have recently been found to correlate with allergic sensitization. Therefore, FeNO may be a useful predictor of atopy in the general population. We sought to determine the diagnostic accuracy of FeNO in predicting atopy in a population-based study.

METHODS

We conducted a cross-sectional study in an age- and sex- stratified random sample of 13 to 15 year-olds in two communities in Peru. We asked participants about asthma symptoms, environmental exposures and sociodemographics, and underwent spirometry, assessment of FeNO and an allergy skin test. We used multivariable logistic regression to model the odds of atopy as a function of FeNO, and calculated area-under-the-curves (AUC) to determine the diagnostic accuracy of FeNO as a predictor of atopy.

RESULTS

Of 1441 recruited participants, 1119 (83%) completed all evaluations. Mean FeNO was 17.6 ppb (SD=0.6) in atopics and 11.6 ppb (SD=0.8) in non-atopics (p<0.001). In multivariable analyses, a FeNO>20 ppb was associated with an increase in the odds of atopy in non-asthmatics (OR=5.3, 95% CI 3.3 to 8.5) and asthmatics (OR=16.2, 95% CI 3.4 to 77.5). A FeNO>20 ppb was the best predictor for atopy with an AUC of 68% (95% CI 64% to 69%). Stratified by asthma, the AUC was 65% (95% CI 61% to 69%) in non-asthmatics and 82% (95% CI 71% to 91%) in asthmatics.

CONCLUSIONS

FeNO had limited accuracy to identify atopy among the general population; however, it may be a useful indicator of atopic phenotype among asthmatics.