Variation in total and specific IgE: effects of ethnicity and socioeconomic status

A systematic review of total IgE reference intervals - A 2024 update

BACKGROUND

Total IgE (tIgE) is a frequently requested analyte in patients presenting with symptoms of atopy. Although tIgE has limited clinical utility in the diagnosis of atopic diseases, it is still important that appropriate reference intervals are provided to the intepreting clinician. Concerns have recently been raised whether laboratories are using outdated tIgE reference intervals. The aim of this study was therefore to perform the first systematic literature review of tIgE reference intervals to aid laboratories in choosing appropriate sources of tIgE reference intervals.

METHODS

A search was performed in MEDLINE, Embase and the Cochrane Library from time of inception to July 2024. Eligible studies had to provide an estimate of paediatric and/or adult tIgE reference intervals using current generation immunoassays. The methodology followed PRISMA guidelines, and the study protocol was registered in the PROSPERO database (CRD42023396441).

RESULTS

A total of 1667 records were screened of which 20 studies remained after the full text review. The studies included 23 910 individuals and covered 18 countries. Upper reference limits varied significantly, with participant selection (inclusion or exclusion of in vitro confirmed specific IgE sensitised individuals) and statistical methods identified as the most important factors influencing the upper reference limit.

CONCLUSION

This review emphasises the need for laboratories to carefully evaluate the participant selection criteria and employed statistical methods whilst determining which tIgE reference intervals are the most appropriate to report to clinicians. Further efforts should also be made to harmonise and improve the reporting of tIgE reference interval studies.

Analyzing Racial Disparities in Pediatric Atopic Comorbidity Emergency Department Visitation Using Electronic Health Records

BACKGROUND

Although atopic diseases and associated comorbidities are prevalent in children, little is known about racial differences in emergency department (ED) visitation.

OBJECTIVE

We sought to examine racial differences in ED visitation among children with allergic comorbidities.

METHODS

We conducted a retrospective study of patients (<21 years) who visited the ED at a large pediatric hospital for atopic dermatitis (AD), food allergy (FA), asthma, allergic rhinitis (AR), and eosinophilic esophagitis (EoE) from 2015 to 2019. We determined the probability of ED encounter-free survival time using hazard ratios (HRs) and time to recurrence (TTR) of ED encounter for patients identified as Black/African American (AA) and White/European American (EA). We assessed potentially underlying allergic, demographic, and place-based factors and potential interactions between factors.

RESULTS

A total of 30,894 patients (38% AA and 62% EA) had 83,078 ED encounters (38,378 first ED encounters and 44,700 recurrent ED encounters) during the study period. Asthma and AR showed the highest rate of comorbidity in ED encounters in both AA and EA children. AA children exhibited a higher HR for encounter following index AD and asthma encounters. We found an interaction between the type of insurance and race in ED encounters for AD, FA, AR, and EoE. In AA children, those insured by Medicaid demonstrated a higher HR for any encounter than those with commercial insurance. Conversely, in EA children, those with Medicaid insurance showed a lower HR than their commercially insured peers. Regardless of race, allergic comorbidity increased the HR of ED encounter (1.12-1.62) for all allergic diseases. At 5-year follow-up, mean differences in TTR were shorter in AA children than EA children in AD, FA, and asthma.

CONCLUSIONS

Identification of disease-specific racial disparities in ED visitation related to atopic diseases is a necessary first step toward the design and implementation of interventions capable of equitably reducing emergency care in atopic comorbid children.

Impact of socioeconomic factors on allergic diseases

Allergic and immunologic conditions, including asthma, food allergy, atopic dermatitis, and allergic rhinitis, are among the most common chronic conditions in children and adolescents that often last into adulthood. Although rare, inborn errors of immunity are life-altering and potentially fatal if unrecognized or untreated. Thus, allergic and immunologic conditions are both medical and public health issues that are profoundly affected by socioeconomic factors. Recently, studies have highlighted societal issues to evaluate factors at multiple levels that contribute to health inequities and the potential steps toward closing those gaps. Socioeconomic disparities can influence all aspects of care, including health care access and quality, diagnosis, management, education, and disease prevalence and outcomes. Ongoing research, engagement, and deliberate investment of resources by relevant stakeholders and advocacy approaches are needed to identify and address the impact of socioeconomics on health care disparities and outcomes among patients with allergic and immunologic diseases.

A survey of total IgE reference intervals reported by Scandinavian and British medical laboratories - a need for harmonisation

OBJECTIVES

There appears to be marked discrepancies between total IgE reference intervals (RIs) in use by many laboratories and those recommended by published studies. The aim of this study was therefore to review total IgE RIs currently reported by Scandinavian and British laboratories and to compare these to published RIs identified by a literature review.

METHODS

Relevant laboratories were identified by test directories provided by the national accreditation bodies in Norway, Sweden, Denmark and the UK. Total IgE RIs and their sources were acquired by accessing laboratory user handbooks or by an electronic survey. In addition a literature review of published total IgE RI studies was performed.

RESULTS

From 172 accredited laboratories providing total IgE analysis, data was acquired from 122 laboratories. An adult upper reference limit between 81 to 150 kU/L was reported by 89% of these. Denmark and Sweden reported the most harmonised RIs whilst Norway and the UK exhibited the least degree of harmonisation. Published adult (n = 6) and paediatric (n = 6) RI studies reported markedly higher upper limits than those currently in use by the laboratories included in this study. There were also large variations in the number of age strata in use for paediatric RIs.

CONCLUSION

This study demonstrates large variations in currently utilised IgE RIs by Scandinavian and British accredited laboratories and most report markedly lower RIs than those recommended by recent RI publications. Many laboratories likely utilise outdated RIs and should consider critically reviewing and updating their RIs.

No impact of helminth coinfection in patients with smear positive tuberculosis on immunoglobulin levels using a novel method measuring Mycobacterium tuberculosis-specific antibodies

Helminth/tuberculosis (TB)-coinfection can reduce cell-mediated immunity against Mycobacterium tuberculosis (Mtb) and increase disease severity, although the effects are highly helminth species dependent. Mtb have long been ranked as the number one single infectious agent claiming the most lives. The only licensed vaccine for TB (BCG) offers highly variable protection against TB, and almost no protection against transmission of Mtb. In recent few years the identification of naturally occurring antibodies in humans that are protective during Mtb infection has reignited the interest in adaptive humoral immunity against TB and its possible implementation in novel TB vaccine design. The effects of helminth/TB coinfection on the humoral response against Mtb during active pulmonary TB are however still unclear, and specifically the effect by globally prevalent helminth species such as Ascaris lumbricoides, Strongyloides stercoralis, Ancylostoma duodenale, Trichuris trichiura. Plasma samples from smear positive TB patients were used to measure both total and Mtb-specific antibody responses in a Peruvian endemic setting where these helminths are dominating. Mtb-specific antibodies were detected by a novel approach coating ELISA-plates with a Mtb cell-membrane fraction (CDC1551) that contains a broad range of Mtb surface proteins. Compared to controls without helminths or TB, helminth/TB coinfected patients had high levels of Mtb-specific IgG (including an IgG1 and IgG2 subclass response) and IgM, which were similarly increased in TB patients without helminth infection. These data, indicate that helminth/TB coinfected have a sustained humoral response against Mtb at the level of active TB only. More studies on the species-specific impact of helminths on the adaptive humoral response against Mtb using a larger sample size, and in relation to TB disease severity, are needed.

IL18 Gene Polymorphism Is Associated with Total IgE in Adult Subjects with Asthma

The allergic asthma phenotype is characterized by a T helper type 2 (Th2) immune response, based on Immunoglobulin E (IgE)-mediated type 1 hypersensitivity reactions. Total IgE is the sum of all IgE types produced by the human body and is used as a biomarker of inflammation in asthma. We analysed data collected in 143 asthma cases (median age 42.1 years) from the general Italian population (GEIRD survey; 2008-2010) to identify single nucleotide polymorphisms (SNPs) in candidate genes that are associated with total IgE in adult subjects with asthma. These patients reported respiratory symptoms in response to perennial allergens and provided data on 166 SNPs tagging 50 candidate genes or gene regions. Replication of the statistically significant results was performed in 842 asthma cases from other European countries (ECRHS II survey; 1998-2002). SNP rs549908 in interleukin 18 (IL18) gene was significantly associated with total IgE in GEIRD, and this result was replicated in ECRHS II. SNP rs1063320 in the human leukocyte antigen G (HLA-G) gene was identified in GEIRD, but this association was not replicated in ECRHS II. Further investigating IL18 and its biological pathways could be important for developing new therapeutic targets, due to its involvement in inflammatory response processes.

Are There Ethnic Differences in Hand Eczema? A Review

Hand eczema is a common disease with economic and social ramifications. This study undertakes a review of certain existing literature to provide insight into contributory factors which may result in the varying prevalence and severity of hand eczema among different ethnic groups, particularly to identify modifiable risk factors, as well as to ascertain knowledge gaps for future research direction. The existing literature suggests that factors including (a) genes, (b) differing skin physiology, (c) cultural practices, (d) dietary habits and associated food preparation, (e) climate, (f) predominant occupations, (g) socioeconomic factors, and (h) dissimilar laws and regulations may account for the disparity in the risk of hand eczema among different ethnicities. Given that endogenous factors cannot be avoided, but certain exogenous aspects can be modified, especially as the environment plays an important role in hand eczema flares, it is helpful from a practical perspective to focus on addressing the modifiable risk factors. These factors pertain to unique cultural practices, customs, and food preparation methods. Healthcare professionals should be well-acquainted with such factors to tailor the treatment approach for patients of different ethnicities accordingly because, with globalization, physicians face increasingly diverse patient populations such that cultural customs no longer remain limited to particular geographic regions.

The prevalence of ultra-low total IgE level among Egyptian population: impact of age, sex, and socioeconomic class

Background

Immunoglobulin E (IgE) is the least prevalent antibody type; it plays a key role in host immunity against parasitic infections and allergic diseases. Association between IgE deficiency and higher malignancy rates has been suggested in many studies.

Objectives

The goal of our study was to determine the prevalence of ultra-low total IgE levels and their variations according to sex and age among the Egyptian population.

Methodology

This multicenter retrospective cross-sectional study included serum total IgE and CBC records of 1099 children and 993 adults recruited from private and public hospitals in Egypt between 2015 and 2021. Total IgE levels were classified into ultra-low, normal, high, and very high.

Results

Of all included subjects, 0.8% had ultra-low IgE levels and 74.4% had normal IgE levels. High and very high serum total IgE levels were 24.1% and 0.7%, respectively. IgE levels were significantly higher among adults than children 45 (16.5–113.25) IU/ml vs. 20 (10–75) IU/ml; p < 0.001and among private hospital’s patients than the public one (40 (15–98.4) IU/ml vs. 25 (10–98.4) IU/ml; p = 0.002. No significant difference between total IgE serum levels regarding gender (p = 0.825). Total IgE levels were higher among young adults, with a gradual decline among older patients and a peak among the 50 s and 60 s patients. Pearson correlation between IgE and absolute eosinophilic count showed positive correlation but did not reach significant level r = 0.04, p = 0.367.

Conclusion

Age and socioeconomic class have impacts on total IgE levels with a relatively low prevalence of ultra-low IgE among the Egyptian population.

Metabo-Endotypes of Asthma Reveal Differences in Lung Function: Discovery and Validation in Two TOPMed Cohorts

Rationale: Current guidelines do not sufficiently capture the heterogeneous nature of asthma; a more detailed molecular classification is needed. Metabolomics represents a novel and compelling approach to derive asthma endotypes (i.e., subtypes defined by functional and/or pathobiological mechanisms). Objectives: To validate metabolomic-driven endotypes of asthma and explore their underlying biology. Methods: In the Genetics of Asthma in Costa Rica Study (GACRS), untargeted metabolomic profiling, similarity network fusion, and spectral clustering was used to identify metabo-endotypes of asthma, and differences in asthma-relevant phenotypes across these metabo-endotypes were explored. The metabo-endotypes were recapitulated in the Childhood Asthma Management Program (CAMP), and clinical differences were determined. Metabolomic drivers of metabo-endotype membership were investigated by meta-analyzing findings from GACRS and CAMP. Measurements and Main Results: Five metabo-endotypes were identified in GACRS with significant differences in asthma-relevant phenotypes, including prebronchodilator (p-ANOVA = 8.3 × 10^-5) and postbronchodilator (p-ANOVA = 1.8 × 10^-5) FEV₁/FVC. These differences were validated in the recapitulated metabo-endotypes in CAMP. Cholesterol esters, trigylcerides, and fatty acids were among the most important drivers of metabo-endotype membership. The findings suggest dysregulation of pulmonary surfactant homeostasis may play a role in asthma severity. Conclusions: Clinically meaningful endotypes may be derived and validated using metabolomic data. Interrogating the drivers of these metabo-endotypes has the potential to help understand their pathophysiology.

Multi-Omics Profiling Approach to Asthma: An Evolving Paradigm

Asthma is a complex multifactorial and heterogeneous respiratory disease. Although genetics is a strong risk factor of asthma, external and internal exposures and their interactions with genetic factors also play important roles in the pathophysiology of asthma. Over the past decades, the application of high-throughput omics approaches has emerged and been applied to the field of asthma research for screening biomarkers such as genes, transcript, proteins, and metabolites in an unbiased fashion. Leveraging large-scale studies representative of diverse population-based omics data and integrating with clinical data has led to better profiling of asthma risk. Yet, to date, no omic-driven endotypes have been translated into clinical practice and management of asthma. In this article, we provide an overview of the current status of omics studies of asthma, namely, genomics, transcriptomics, epigenomics, proteomics, exposomics, and metabolomics. The current development of the multi-omics integrations of asthma is also briefly discussed. Biomarker discovery following multi-omics profiling could be challenging but useful for better disease phenotyping and endotyping that can translate into advances in asthma management and clinical care, ultimately leading to successful precision medicine approaches.

Genome-wide association study of asthma, total IgE, and lung function in a cohort of Peruvian children

BACKGROUND

Genetic ancestry plays a role in asthma health disparities.

OBJECTIVE

Our aim was to evaluate the impact of ancestry on and identify genetic variants associated with asthma, total serum IgE level, and lung function.

METHODS

A total of 436 Peruvian children (aged 9-19 years) with asthma and 291 without asthma were genotyped by using the Illumina Multi-Ethnic Global Array. Genome-wide proportions of indigenous ancestry populations from continental America (NAT) and European ancestry from the Iberian populations in Spain (IBS) were estimated by using ADMIXTURE. We assessed the relationship between ancestry and the phenotypes and performed a genome-wide association study.

RESULTS

The mean ancestry proportions were 84.7% NAT (case patients, 84.2%; controls, 85.4%) and 15.3% IBS (15.8%; 14.6%). With adjustment for asthma, NAT was associated with higher total serum IgE levels (P < .001) and IBS was associated with lower total serum IgE levels (P < .001). NAT was associated with higher FEV1 percent predicted values (P < .001), whereas IBS was associated with lower FEV1 values in the controls but not in the case patients. The HLA-DR/DQ region on chromosome 6 (Chr6) was strongly associated with total serum IgE (rs3135348; P = 3.438 × 10-10) and was independent of an association with the haplotype HLA-DQA1∼HLA-DQB1:04.01∼04.02 (P = 1.55 × 10-05). For lung function, we identified a locus (rs4410198; P = 5.536 × 10-11) mapping to Chr19, near a cluster of zinc finger interacting genes that colocalizes to the long noncoding RNA CTD-2537I9.5. This novel locus was replicated in an independent sample of pediatric case patients with asthma with similar admixture from Brazil (P = .005).

CONCLUSION

This study confirms the role of HLA in atopy, and identifies a novel locus mapping to a long noncoding RNA for lung function that may be specific to children with NAT.

Lower Use of Biologics for the Treatment of Asthma in Publicly Insured Individuals

BACKGROUND

Despite bearing a disproportionate burden of poorly controlled asthma, publicly insured individuals are less likely to receive biologics.

OBJECTIVE

To assess biologic use by payer among individuals with asthma.

METHODS

We used IQVIA's National Disease and Therapeutic Index, a nationally representative, all-payer audit of ambulatory care in the United States, to describe the patterns of use by payer.

RESULTS

Asthma treatment visits in which a biologic product was reported increased from approximately 0.1% of asthma-related visits in 2003 to 1% in 2015 and doubled to 2% by 2019. Omalizumab use initially increased from 2003 to 2006 and plateaued till 2015 when its use declined modestly, coinciding with the release of additional biologic products. In 2019, omalizumab accounted for 37% of biologic treatment visits, mepolizumab 21%, benralizumab 27%, dupilumab 15%, and reslizumab <1%. Biologic treatment visits were higher for privately insured individuals (28.3 per 1000 visits) compared with publicly insured individuals (16.3 per 1000 visits). This difference persisted after accounting for age, sex, and race using nationally representative estimates. White patients accounted for a disproportionate amount of biologic treatment visits among the publicly insured (80%) despite accounting for only 60% of publicly insured asthma treatment visits. No biologic treatment visits were observed for individuals who were uninsured. Half of dupilumab visits were for publicly insured patients, compared with 22% of mepolizumab/benralizumab and 27% of omalizumab visits.

CONCLUSION

Biologics were uncommonly used among patients with asthma, and the basis for disproportionately lower use of biologics among the publicly insured, where the burden of uncontrolled asthma is greatest, merits further investigation.

Ethnic Differences in Severe Asthma Clinical Care and Outcomes: An Analysis of United Kingdom Primary and Specialist Care

BACKGROUND

Understanding the effects of ethnicity in severe asthma is important for optimal personalized patient care.

OBJECTIVE

To assess ethnic differences in disease control, exacerbations, biological phenotype, and treatment in severe asthma in the United Kingdom.

METHODS

We compared demographics, type 2 biomarkers, lung function, asthma control, medications, and health care use between White and underrepresented ethnic group patients in the UK Severe Asthma Registry (UKSAR) and Optimum Patient Care Research Database (OPCRD).

RESULTS

A total of 3637 patients (665 from the underrepresented ethnic group) were included from UKSAR and 10,549 (577 from the underrepresented ethnic group) from OPCRD. Patients in the underrepresented ethnic group had higher levels of uncontrolled disease when measurements were made using the asthma control questionnaire in UKSAR (odds ratio [OR] = 1.47; 95% confidence interval [CI], 1.12-1.93) and the Royal College of Physicians 3 Questions in OPCRD (OR = 1.82; 95% CI, 1.27-2.60). Although exacerbation rates were similar, patients in the underrepresented ethnic group were more likely to have recently attended the emergency department (OR = 1.55; 95% CI, 1.26-1.92) or to have been hospitalized (OR = 1.31; 95% CI, 1.07-1.59) owing to asthma. Inflammatory biomarkers were consistently higher in the underrepresented ethnic group, including blood eosinophils in OPCRD (ratio = 1.12; 95% CI, 1.05-1.20) and in UKSAR blood eosinophils (ratio = 1.16; 95% CI, 1.06-1.27), FeNO (ratio = 1.14; 95% CI, 1.04-1.26), and IgE (ratio = 1.70; 95% CI, 1.47-1.97). Patients in the underrepresented ethnic group were more likely to be atopic in the UKSAR (OR = 1.32; 95% CI, 1.07-1.63) and OPCRD (OR = 1.67; 95% CI, 1.26-2.21), and less likely to be using maintenance oral corticosteroids at referral (OR = 0.75; 95% CI, 0.61-0.92).

CONCLUSIONS

Severe asthma patients from underrepresented ethnic groups presented with a higher disease burden and were more likely to attend the emergency department. They had a distinct phenotypic presentation and differences in medicine use, with higher levels of type 2 biomarkers.

Inborn errors of immunity with atopic phenotypes: A practical guide for allergists

Inborn errors of immunity (IEI) are a heterogeneous group of disorders, mainly resulting from mutations in genes associated with immunoregulation and immune host defense. These disorders are characterized by different combinations of recurrent infections, autoimmunity, inflammatory manifestations, lymphoproliferation, and malignancy. Interestingly, it has been increasingly observed that common allergic symptoms also can represent the expression of an underlying immunodeficiency and/or immune dysregulation.

Very high IgE levels, peripheral or organ-specific hypereosinophilia, usually combined with a variety of atopic symptoms, may sometimes be the epiphenomenon of a monogenic disease. Therefore, allergists should be aware that severe and/or therapy-resistant atopic disorders might be the main clinical phenotype of some IEI. This could pave the way to target therapies, leading to better quality of life and improved survival in affected patients.

Investigation of Serum Total IgE and Eosinophil Levels in Different Allergic Diseases Together with the Study of Their Correlations with Various Possible Allergens in Mosul City

Serum total IgE (tIgE) is frequently used in the diagnosis of allergic diseases in Mosul city and Iraq. However, neither normal nor elevated levels can exclude or confirm the diagnosis of these diseases. Here, we tried to evaluate the validity of tIgE in the diagnosis of allergic asthma(AS), allergic rhinitis(AR) and atopic dermatitis(AD) in a sample of Mosul population, to set up an optimum cut-off value for diagnosis of these diseases and to study its correlation with different parameters that might affect its level. 38 patients with AS, 27 with AR, 46 with AD and 45 healthy controls were included in this study. tIgE were determined by ELISA and compared between allergic diseases and controls. Blood eosinophilia was ascertained and correlated with tIgE levels. The geometric means of tIgE were 316.87 IU/ml (95% CI: 234.69 to 427.82) in AS, 262.07 IU/ml (95% CI:174.24 to 394.18) in AR and 270.48 IU/ml (95% CI:202.57 to 361.16) in AD compared to 16.90 IU/ml (95% CI:12.32 to 23.18) in healthy controls. tIgE in allergic diseases was significantly increased in comparison to healthy controls (P <.0001). Female gender influenced tIgE in AS, but not in AR or AD. tIgE predominated in younger age groups; however, no significant difference was found between younger and older groups. Optimum values for tIgE with best discriminative accuracy were 77 IU/ml for AS and 81 IU/ml for AR and AD. Eosinophils count appeared to be a useful adjunct, and correlate well with tIgE in the diagnosis of allergic diseases.

Resolving Clinical Phenotypes into Endotypes in Allergy: Molecular and Omics Approaches

Allergic diseases are highly complex with respect to pathogenesis, inflammation, and response to treatment. Current efforts for allergic disease diagnosis have focused on clinical evidence as a binary outcome. Although outcome status based on clinical phenotypes (observable characteristics) is convenient and inexpensive to measure in large studies, it does not adequately provide insight into the complex molecular determinants of allergic disease. Individuals with similar clinical diagnoses do not necessarily have similar disease etiologies, natural histories, or responses to treatment. This heterogeneity contributes to the ineffective response to treatment leading to an annual estimated cost of $350 billion in the USA alone. There has been a recent focus to deconvolute the clinical heterogeneity of allergic diseases into specific endotypes using molecular and omics approaches. Endotypes are a means to classify patients based on the underlying pathophysiological mechanisms involving distinct functions or treatment response. The advent of high-throughput molecular omics, immunophenotyping, and bioinformatics methods including machine learning algorithms is facilitating the development of endotype-based diagnosis. As we move to the next decade, we should truly start treating clinical endotypes not clinical phenotype. This review highlights current efforts taking place to improve allergic disease endotyping via molecular omics profiling, immunophenotyping, and machine learning approaches in the context of precision diagnostics in allergic diseases. Graphical Abstract.

Racial disparities in allergic outcomes persist to age 10 years in black and white children

BACKGROUND

Previous analyses in the WHEALS birth cohort demonstrated that black children are more likely to experience allergic outcomes than white children by age 2 years. The results could not be explained by a host of variables.

OBJECTIVE

Assess whether racial disparities persisted to age 10 years and determine whether any differences could be explained by a panel of variables related to early life exposures in WHEALS.

METHODS

At age 10 years, WHEALS children (n = 481) completed skin prick testing, spirometry and methacholine challenge, and a physician examination for eczema and asthma. Allergen-specific immunoglobulin Es (sIgE) and total IgE were measured. Inverse probability weighting with logistic and linear regression models was used to assess associations between race (black or white) and the outcomes.

RESULTS

Black children fared worse than white children with respect to each outcome. Black children were more likely to have eczema, asthma, sensitization (≥1 sIgE ≥ 0.35 IU/L) and at least 1 positive skin pick test; however, some variability was present in the magnitudes of association within subgroups defined by delivery mode, sex of the child, prenatal indoor dog exposure, and firstborn status. In some subgroups, black children were also more likely to have higher total IgE and worse pulmonary function test measures (PC 20 ≤ 25 mg/mL, % predicted forced vital capacity [FVC], forced expiratory volume in 1 second [FEV₁]/FVC, forced expiratory flow from 25% to 75% of vital capacity [FEF_25-75]). Confounding did not explain these differences.

CONCLUSION

Racial differences persisted in this cohort through age 10 years. Future studies should include potentially important, but rarely studied factors such as segregation and structural racism, because these factors could explain the observed racial differences.

Long-term Breastfeeding in the Prevention of Allergic Rhinitis: Allergic Rhinitis Cohort Study for Kids (ARCO-Kids Study)

OBJECTIVES

There is a great deal of interest in the possibility that environmental factors may influence the risk of developing allergic rhinitis (AR) in early life. We investigated the simultaneous effects of mode of delivery and duration of breastfeeding on the development of AR in children.

METHODS

Data from 1,374 children participating in the Allergic Rhinitis Cohort Study for kids (ARCO-kids study) was analyzed. All subjects were divided into AR or non-allergic rhinitis (NAR) groups. Data on environmental factors, mode of delivery and duration of breastfeeding were collected using a questionnaire.

RESULTS

Compared with short-term breastfeeding (<6 months), long-term breastfeeding (≥12 months) was significantly associated with a lower prevalence of AR (adjusted odds ratio [aOR], 0.54; 95% confidence interval [CI], 0.34 to 0.88). Children in the AR group also had a higher cesarean delivery rate than those in the NAR group (39.1% vs. 32.8%, P=0.05). Regarding the combined effects of mode of delivery and duration of breastfeeding, long-term breastfeeding with a vaginal delivery strongly suppressed the development of AR, compared to short-term breastfeeding with a cesarean delivery (aOR, 0.47; 95% CI, 0.30 to 0.73).

CONCLUSION

Long-term breastfeeding (≥12 months) and a vaginal delivery are associated with a lower risk of developing childhood AR.

Serum periostin levels in adults of Chinese descent: an observational study

BACKGROUND

Periostin has been shown to be a marker of Type 2 airway inflammation, associated with airway eosinophilia. It has a potential role in identifying asthmatics who may be responsive to treatment with monoclonal antibody therapy directed against Type 2 cytokines, such as interleukin (IL)-13, IL-4 receptor subunit-α and immunoglobulin E. The clinical utility of periostin measurements depends on better understanding of factors that may affect serum periostin levels, such as race. We aimed to identify the ranges of serum periostin in Chinese adults both with and without asthma, and compare them with those previously identified in Caucasian adults.

METHODS

A two-centred cross-sectional study, recruiting 188 Chinese adults, aged 18 to 75 years. 120 participants had no history of asthma or chronic obstructive pulmonary disease. 68 participants had a doctor's diagnosis of asthma and were on current treatment. Univariate comparisons of periostin by dichotomous variables were made using t-tests with logarithmic transformation as the distribution of periostin was skewed.

RESULTS

In the Chinese non-asthma group, periostin levels were sex-, but not age-dependent, with females having higher periostin levels. The individual predicted (90% CI) reference range for periostin in females was 61.1 ng/ml (41.6 to 89.8) ng/ml and in males was 53.2 ng/ml (36.1 to 78.3) ng/ml. There was no difference in median serum periostin levels between Chinese non-asthmatics and Chinese asthmatics, 57.0 versus 56.8 ng/ml, difference (95% CI) 0.1 (- 4.2 to 4.2) ng/ml, P = 0.94. The median serum periostin levels were higher in Chinese non-asthmatics than Caucasian non-asthmatics, 57.0 versus 49.7 ng/ml, difference (95% CI) 8.2 (5.8-10.6) ng/ml, P < 0.001.

CONCLUSIONS

Serum periostin does not discriminate between asthmatics and non-asthmatics and is therefore not a good biomarker to diagnose asthma. Serum periostin levels were higher in the Chinese compared to the Caucasian non-asthma group, and also sex dependent in the Chinese participants. There was no difference in serum periostin levels between Chinese non-asthma and asthma groups. This suggests that ethnicity should be considered in the interpretation of periostin levels in asthma patients and sex is an additional consideration in Chinese patients.Trial registration This trial was prospectively registered with Australian New Zealand Clinical Trials Registry (ACTRN12614000122651).

Hyper-IgE in the allergy clinic--when is it primary immunodeficiency?

The 2017 International Union of Immunological Societies (IUIS) classification recognizes 3 hyper-IgE syndromes (HIES), including the prototypic Job's syndrome (autosomal dominant STAT3-loss of function) and autosomal recessive PGM3 and SPINK5 syndromes. Early diagnosis of PID can direct life-saving or transformational interventions; however, it remains challenging owing to the rarity of these conditions. This can result in diagnostic delay and worsen prognosis. Within increasing access to "clinical-exome" testing, clinicians need to be aware of the implication and rationale for genetic testing, including the benefits and limitations of current therapies. Extreme elevation of serum IgE has been associated with a growing number of PID syndromes including the novel CARD11 and ZNF341 deficiencies. Variable elevations in IgE are associated with defects in innate, humoral, cellular and combined immunodeficiency syndromes. Barrier compromise can closely phenocopy these conditions. The aim of this article was to update readers on recent developments at this important interface between allergy and immunodeficiency, highlighting key clinical scenarios which should draw attention to possible immunodeficiency associated with extreme elevation of IgE, and outline initial laboratory assessment and management.

Effect of multi-ethnicity and ancestry on prevalence of allergic disease

BACKGROUND/PURPOSE

Differences exist among racial and ethnic groups in the prevalence and severity of allergic diseases. However, influence of population admixing on allergic disease has not been studied. We examined the effect of population admixing on the occurrence of allergic disease.

METHODS

We reviewed the data of 68,043 adolescents who participated in the 11th Korea Youth Risk Behavior Web-based Survey, which provides a sample that is representative of the entire Korean middle school and high school student population. Multi-ethnic status was determined by using parental country of birth and prevalence of asthma, allergic rhinitis (AR), and atopic dermatitis (AD) was determined by questionnaire.

RESULTS

Multi-ethnic adolescents accounted for approximately 0.9% of the total adolescents. Prevalence of asthma was significantly higher in multi-ethnic group than non multi-ethnic group while that of AR and AD was significantly higher in non multi-ethnic group than multi-ethnic group. Parental region of country at birth showed a significant difference in prevalence of allergic disease. Univariate analysis found that urbanity, perceived economic status (PES), parental region of country at birth, and environmental tobacco smoke (ETS) showed a significant odds ratio (OR) in asthma, AR, and AD. Body mass index (BMI) showed a significant OR in asthma and AD. After adjusting for urbanity, PES, BMI and ETS, multiethnicity showed significantly lower OR in AR and AD.

CONCLUSION

Population admixing appears to have significant effect on the prevalence of allergic disease. Further study will be needed to clarify the effect of population admixing on prevalence of allergic disease.

Food Allergy in Children: An Overview

The estimated prevalence of food allergy amongst children in the west is around 6-8% but there is paucity of data in the Indian population. There is a complex interplay of environmental influences and genetic factors in the immuno-pathogenesis and manifestations of food allergy. A reliable thorough clinical history, combined with positive skin prick tests or food-specific IgE, is essential for a more precise diagnosis of food allergy. Currently there is no cure for food allergy. The management of food allergy usually includes strict avoidance, patient education and provision of emergency medication (adrenaline-autoinjectors). Emerging therapies based on evolving research are focused on a more active approach to management which includes early introduction of potentially allergenic foods, anticipatory testing and desensitisation to food allergens. Lack of food labelling policy and non availability of adrenaline auto-injectors is a huge limiting factor for effective management of food allergy among children in India. The present review focuses on IgE mediated food allergy.

What Ancestry Can Tell Us About the Genetic Origins of Inter-Ethnic Differences in Asthma Expression

Differences in asthma prevalence have been described across different populations, suggesting that genetic ancestry can play an important role in this disease. In fact, several studies have demonstrated an association between African ancestry with increased asthma susceptibility and severity, higher immunoglobulin E levels, and lower lung function. In contrast, Native American ancestry has been shown to have a protective role for this disease. Genome-wide association studies have allowed the identification of population-specific genetic variants with varying allele frequency among populations. Additionally, the correlation of genetic ancestry at the chromosomal level with asthma and related traits by means of admixture mapping has revealed regions of the genome where ancestry is correlated with the disease. In this review, we discuss the evidence supporting the association of genetic ancestry with asthma susceptibility and asthma-related traits, and highlight the regions of the genome harboring ancestry-specific genetic risk factors.

Fungal Sensitization Is Associated with Increased Risk of Life-Threatening Asthma

BACKGROUND

Fungal sensitization in patients with asthma has been associated with severe asthma and worse asthma outcomes.

OBJECTIVE

The purpose of this study was to determine the relationship between fungal and nonfungal sensitization, asthma severity, and clinical outcomes.

METHODS

A retrospective review of patients with asthma evaluated in an urban pulmonary subspecialty clinic in the United States was performed. Patients with fungal and nonfungal allergen sensitization were identified based on serum-specific immunoglobulin E (sIgE) testing. Demographic, clinical, laboratory, and spirometric data were obtained. The relationship between fungal sensitization and asthma outcomes was examined.

RESULTS

Of 390 patients with asthma identified, 307 had sIgE testing, of whom 53 (17.3%) had fungal sensitization, 117 (38.1%) had nonfungal sensitization, and 137 (44.6%) had no sensitization. Patients with fungal sensitization were more likely to be sensitized to ≥5 allergens than patients with nonfungal sensitization (66% for fungal vs 29% for nonfungal, P < .001). Serum IgE concentrations were highest in patients with fungal sensitization compared with patients with no sensitization or nonfungal sensitization (median, 825, 42, and 203 IU/mL, respectively, P < .001). Fungal sensitized patients were more likely to require intensive care unit (ICU) admission and mechanical ventilation than those with no sensitization or nonfungal sensitization (13.2%, 3.7%, and 3.4%, respectively, for ICU admission, P = .02; 11.3%, 1.5%, and 0.9%, respectively, for ventilation, P < .001).

CONCLUSIONS

Fungal sensitization is common in patients with asthma in an urban setting and is associated with greater sensitization to nonfungal allergens and increased risk of life-threatening asthma.

Resolving the etiology of atopic disorders by using genetic analysis of racial ancestry

Atopic dermatitis (AD), food allergy, allergic rhinitis, and asthma are common atopic disorders of complex etiology. The frequently observed atopic march from early AD to asthma, allergic rhinitis, or both later in life and the extensive comorbidity of atopic disorders suggest common causal mechanisms in addition to distinct ones. Indeed, both disease-specific and shared genomic regions exist for atopic disorders. Their prevalence also varies among races; for example, AD and asthma have a higher prevalence in African Americans when compared with European Americans. Whether this disparity stems from true genetic or race-specific environmental risk factors or both is unknown. Thus far, the majority of the genetic studies on atopic diseases have used populations of European ancestry, limiting their generalizability. Large-cohort initiatives and new analytic methods, such as admixture mapping, are currently being used to address this knowledge gap. Here we discuss the unique and shared genetic risk factors for atopic disorders in the context of ancestry variations and the promise of high-throughput "-omics"-based systems biology approach in providing greater insight to deconstruct their genetic and nongenetic etiologies. Future research will also focus on deep phenotyping and genotyping of diverse racial ancestry, gene-environment, and gene-gene interactions.

Atopy, but not obesity is associated with asthma severity among children with persistent asthma

BACKGROUND AND OBJECTIVE

Obesity is associated with an increased risk of asthma in children. Atopic sensitization is a major risk factor for asthma including severe asthma in children. It is unclear if obesity is associated with worse asthma control or severity in children and how its effects compare to atopy. We sought to examine relationships of weight status and atopy to asthma control and severity among a population of predominantly low income, minority children and adolescents with persistent asthma.

METHODS

A cross-sectional analysis of 832 children and adolescents, age range 5-17 years, with persistent asthma was performed. Clinical assessments included asthma questionnaires of symptoms, asthma severity score, health care utilization and medication treatment step, lung function testing, and skin prick testing as well as measures of adiposity. Data were collected between December 2010 and August 2014 from Johns Hopkins Hospital in Baltimore, MD and Children's Hospital of Boston, MA.

RESULTS

Obesity was not associated with worse asthma control or severity in this group of predominantly low income, minority children and adolescents with persistent asthma. However, a greater degree of atopy was associated with lower lung function, higher asthma severity score, and higher medication treatment step.

CONCLUSION

Atopy may be a more important risk factor for asthma severity than obesity among low-income minority children and adolescents with persistent asthma living in Northeastern cities in the United States.

Sensitization to milk, egg and peanut from birth to 18 years: A longitudinal study of a cohort at risk of allergic disease

BACKGROUND

Longitudinal data on the natural history of food sensitization beyond early childhood are scarce. We aimed to investigate the natural history of milk, egg and peanut sensitization from infancy to 18 years and assess whether early food sensitization predicted adolescent food allergy.

METHODS

Sensitization to cow's milk, hen's egg and peanut was measured by skin prick testing at ages 6 months, 1, 2, 12 and 18 years in a high-risk allergy birth cohort (n = 620). Generalized additive models investigated interactions with sex, eczema and aeroallergen sensitization in infancy. Logistic regression assessed the relationships between early food sensitization and adolescent sensitization and probable food allergy up to 18 years.

RESULTS

The prevalence of egg and peanut sensitization peaked at 12 months, while milk sensitization peaked at both 1 and 12 years. Boys with early eczema had the highest prevalences of milk and egg sensitization throughout follow-ups. However, neither sex nor eczema influenced the prevalence of peanut sensitization over time. New onset food sensitization beyond the age of 2 was observed in 7% of participants. Food sensitization at 12 months was associated with increased risk of adolescent food sensitization and adolescent probable food allergy, with sensitization to more than one food allergen had the strongest predictor.

CONCLUSIONS

Food sensitization prevalence is highest in infancy and declines after 12 months of age. Boys with early-life eczema have the highest prevalence of milk and egg sensitization. Food sensitization at 12 months can predict children at greater risk of adolescent sensitization and probable food allergy at 12 and 18 years.

Genome-wide association study and admixture mapping reveal new loci associated with total IgE levels in Latinos

BACKGROUND

IgE is a key mediator of allergic inflammation, and its levels are frequently increased in patients with allergic disorders.

OBJECTIVE

We sought to identify genetic variants associated with IgE levels in Latinos.

METHODS

We performed a genome-wide association study and admixture mapping of total IgE levels in 3334 Latinos from the Genes-environments & Admixture in Latino Americans (GALA II) study. Replication was evaluated in 454 Latinos, 1564 European Americans, and 3187 African Americans from independent studies.

RESULTS

We confirmed associations of 6 genes identified by means of previous genome-wide association studies and identified a novel genome-wide significant association of a polymorphism in the zinc finger protein 365 gene (ZNF365) with total IgE levels (rs200076616, P = 2.3 × 10(-8)). We next identified 4 admixture mapping peaks (6p21.32-p22.1, 13p22-31, 14q23.2, and 22q13.1) at which local African, European, and/or Native American ancestry was significantly associated with IgE levels. The most significant peak was 6p21.32-p22.1, where Native American ancestry was associated with lower IgE levels (P = 4.95 × 10(-8)). All but 22q13.1 were replicated in an independent sample of Latinos, and 2 of the peaks were replicated in African Americans (6p21.32-p22.1 and 14q23.2). Fine mapping of 6p21.32-p22.1 identified 6 genome-wide significant single nucleotide polymorphisms in Latinos, 2 of which replicated in European Americans. Another single nucleotide polymorphism was peak-wide significant within 14q23.2 in African Americans (rs1741099, P = 3.7 × 10(-6)) and replicated in non-African American samples (P = .011).

CONCLUSION

We confirmed genetic associations at 6 genes and identified novel associations within ZNF365, HLA-DQA1, and 14q23.2. Our results highlight the importance of studying diverse multiethnic populations to uncover novel loci associated with total IgE levels.

The effects of alcohol consumption and smoking on allergy risk in Korean adults

BACKGROUND

The immune-modulating effects of alcohol and smoking are well known through a great body of research. Furthermore, many studies have been performed on the influence of alcohol and smoking on the development of allergic disease. However, previous studies have reported conflicting results with associations between alcohol intake or smoking and risk of allergy. The purpose of this study was to evaluate the effects of alcohol consumption and smoking on total serum immunoglobulin E (TIgE) and prevalence of sensitization to Dermatophagoides farinae in a representative sample of Korean adults.

METHODS

TIgE levels and IgE levels specific to D. farinae were measured. Alcohol, smoking habit, and other influencing variables were obtained from the 2010 Korean National Health and Nutrition Examination.

RESULTS

Smoking (smoked five packs or more in lifetime) was independently associated with increased risk of sensitization to D. farinae (odds ratio [OR], 1.439; 95% CI, 1.075-1.927). Frequent alcohol drinking (more than four times a week) also showed similar association when compared with subjects who drank less than once per month (OR, 2.052; 95% CI, 1.257-3.350). TIgE levels were also increased along with increased frequency of alcohol drinking. However, smoking habit was not related to TIgE levels.

CONCLUSION

These findings suggest that history of smoking and frequent alcohol consumption are significantly associated with increased prevalence of sensitization to D. farinae. In addition, frequency of alcohol drinking was also related to a moderate increase in TIgE levels in Korean adults.

Nocturnal asthma and the importance of race/ethnicity and genetic ancestry

RATIONALE

Nocturnal asthma is a common presentation and is associated with a more severe form of the disease. However, there are few epidemiologic studies of nocturnal asthma, particularly in minority populations.

OBJECTIVES

To identify factors associated with nocturnal asthma, including the contribution of self-identified race/ethnicity and genetic ancestry.

METHODS

The analysis included individuals from the Study for Asthma Phenotypes and Pharmacogenomic Interactions by Race-ethnicity (SAPPHIRE) cohort. Nocturnal asthma symptoms were assessed by questionnaire. Genome-wide genotype data were used to estimate genetic ancestry in a subset of African American participants. Logistic regression was used evaluate the association of various factors with nocturnal asthma, such as self-identified race/ethnicity and genetic ancestry.

MEASUREMENT AND MAIN RESULTS

The study comprised 3,380 African American and 1,818 European Americans individuals with asthma. After adjusting for other potential explanatory variables, including controller medication use, African Americans were more than twice as likely (odds ratio, 2.56; 95% confidence interval, 2.24-2.93) to report nocturnal asthma when compared with European American individuals. Among the subset of African American participants with genome-wide genotype data (n = 1,040), estimated proportion of African ancestry was also associated with an increased risk of nocturnal asthma (P = 0.007). Differences in lung function explained a small, but statistically significant (P = 0.02), proportion of the relationship between genetic ancestry and nocturnal asthma symptoms.

CONCLUSIONS

Both self-identified race/ethnicity and African ancestry appear to be independent predictors of nocturnal asthma. The mechanism by which genetic ancestry contributes to population-level differences in nocturnal asthma appears to be largely independent of lung function.

Factors associated with degree of atopy in Latino children in a nationwide pediatric sample: the Genes-environments and Admixture in Latino Asthmatics (GALA II) study

BACKGROUND

Atopy varies by ethnicity, even within Latino groups. This variation might be due to environmental, sociocultural, or genetic factors.

OBJECTIVE

We sought to examine risk factors for atopy within a nationwide study of US Latino children with and without asthma.

METHODS

Aeroallergen skin test responses were analyzed in 1830 US Latino subjects. Key determinants of atopy included country/region of origin, generation in the United States, acculturation, genetic ancestry, and site to which subjects migrated. Serial multivariate zero-inflated negative binomial regressions stratified by asthma status examined the association of each key determinant variable with the number of positive skin test responses. In addition, the independent effect of each key variable was determined by including all key variables in the final models.

RESULTS

In baseline analyses African ancestry was associated with 3 times (95% CI, 1.62-5.57) as many positive skin test responses in asthmatic participants and 3.26 times (95% CI, 1.02-10.39) as many positive skin test responses in control participants. Generation and recruitment site were also associated with atopy in crude models. In final models adjusted for key variables, asthmatic patients of Puerto Rican (exp[β] [95% CI], 1.31 [1.02-1.69]) and mixed (exp[β] [95% CI], 1.27 [1.03-1.56]) ethnicity had a greater probability of positive skin test responses compared with Mexican asthmatic patients. Ancestry associations were abrogated by recruitment site but not region of origin.

CONCLUSIONS

Puerto Rican ethnicity and mixed origin were associated with degree of atopy within US Latino children with asthma. African ancestry was not associated with degree of atopy after adjusting for recruitment site. Local environment variation, represented by site, was associated with degree of sensitization.

Racial differences in allergic sensitization: recent findings and future directions

Racial disparities are present in many facets of health and disease. Allergy and asthma are no exceptions. Secondary results from cross-sectional and cohort studies have provided information on the scope of racial disparities in allergic sensitization in the United States. African American/Black individuals tend to be sensitized more frequently than White individuals. Little is known about rates in other race groups. Genetics are unlikely to be the sole or major cause of the observed differences. Home dust allergen and endotoxin levels cannot explain the differences. Studies that have been designed to specifically address the sources of these racial disparities are needed. A "Multilevel Framework" that considers the roles of the individual, family and community presents an excellent approach to guide design of future studies of the causes of these disparities. Understanding the causes of the disparities could lead to interventions that would improve the health of all individuals.

The relationship of season of birth to asthma and allergy in urban African American children from 10 to 13 years of age

OBJECTIVES

To assess the relationship between season of birth and presence of asthma and allergy in preteen, low-income, African American children.

METHODS

The study consisted of a self-administered survey followed by telephone interviews of parents of children attending 19 middle schools in Detroit, Michigan. Out of 4194 children, 1292 were identified with asthma and 962 parents of these children provided informed consent and took part in telephone interviews.

RESULTS

No statistically significant relationships were observed between season of birth and diagnosis of asthma (p > .05) or with diagnosis adjusting for income, age, gender, parent's education, or parent being a smoker (p > .05). No statistically significant association was evident between season of birth and presence of allergy (p > .05) or with allergy adjusting for the above variables (p > .05).

CONCLUSIONS

Identifying children vulnerable to problems with asthma and allergy, especially in populations exhibiting high prevalence of the conditions and significant disparities in outcomes, requires use of all possible means. Season of birth does not appear to be a useful indicator in identification of such children. The findings from this study do not support the proposition that season of birth, associated with early exposure to viruses as evident in the winter and to seasonal allergens, contributes to more asthma and/or allergy.

Genome-wide scan on total serum IgE levels identifies no common variants in a healthy Chinese male population

Immunoglobulin E (IgE) provides important information on the humoral immune status, and the IgE level is routinely detected in clinical practice. There are many diseases associated with IgE, such as atopic disease, autoimmune diseases, and so on. IgE is a genetically complex trait, but comprehensive genetic assessment of the variability in serum IgE levels is lacking. Previous genome-wide association studies (GWAS) on total serum IgE levels have identified FCER1A as the susceptibility locus; however, the candidate gene association study in southern Chinese patients reported no association. Given the genetic difference in different populations, we firstly conducted this two-stage GWAS in a Chinese population of 3,495 men, including 1,999 unrelated subjects in the first stage and 1,496 independent individuals replicated in the second stage. In the first stage, we totally identified three single nucleotide polymorphisms (SNPs) which reached a P value of 1.0 × 10⁻⁵. Rs17090302 on chromosome 3 and Rs28708846 on chromosome 13 are intergenic. Rs432085 from chromosome 3p28 is located in the gene CCDC50. When the two-stage data was combined, none of the SNPs reached the genome-wide significant level. Collectively, we did not identify novel loci associated with the serum IgE level in Chinese males, but we hypothesized that CCDC50 was a candidate gene in regulation on IgE level.

Paediatric oral peanut challenges: a comparison of practice in London and western Switzerland

BACKGROUND

There are guidelines on how to develop a food challenge protocol, but at present there is no gold standard guidance on method, and separate units produce differing protocols.

METHODS

We performed a retrospective analysis of 200 patients' data from the paediatric allergy units in Lausanne and Geneva, Western Switzerland, and St Thomas' Hospital (STH), UK.

RESULTS

St Thomas' Hospital has a younger cohort with a lower overall mean spIgE (2.36 kU/l vs. 8.00 kU/l, P = 0.004). The target peanut protein volumes differed: Switzerland 4.4 g vs. STH 8.4 g. Despite this, the dose actually achieved in positive challenges was not significantly different (2.33 g vs. 1.49 g, P = 0.16). 26% of challenges reacted at 4 g or more of peanut protein.

CONCLUSIONS

The differences in results highlight how the variation in reasoning behind food challenge alters the outcome. Standardization of food challenges would allow easy comparison between hospitals and geographical areas for research purposes.

Assessment of Total/Specific IgE Levels Against 7 Inhalant Allergens in Children Aged 3 to 6 Years in Seoul, Korea

PURPOSE

Childhood allergies are a serious problem, as they may lead to lifetime chronic disease. Determination of total and specific IgE levels is known to be a diagnostic tool for allergic sensitization; however, IgE levels are affected by various factors, such as age, sex, ethnicity, and geographic area. Thus, we evaluated the distribution of total and specific serum IgE levels against seven inhalant allergens in preschool children and examined their association with allergic diseases in Seoul, Korea.

METHODS

Total/specific serum IgE determination and skin prick tests for seven common allergens were performed on 509 children aged 3 to 6 years from 16 child care centers in Seoul, Korea. Demographic characteristics were surveyed from parents using a modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. A diagnosis of atopic dermatitis was made by physicians.

RESULTS

The geometric mean of total IgE was 80.48±3.80 kU/L in preschool children. IgE levels were higher in boys (boys, 102.34±3.52 kU/L; girls, 62.37±3.93 kU/L; P<0.001) and atopic subjects (atopic, 158.00±3.35 kU/L; non-atopic, 52.75±3.44 kU/L; P<0.001). An increased prevalence of atopy was associated with a high monthly household income (P=0.004) and higher maternal education level (above university-level education; P=0.009), as well as increased total IgE levels (P=0.036). Physician-diagnosed atopic dermatitis was associated with sensitization to inhalant allergens.

CONCLUSIONS

Total IgE levels were very high as compared with those in previous reports from other countries. The most common sensitized allergen was Dermatophagoides farinae, and the positive response rate peaked at age 3 years and was maintained thereafter, particularly in boys. Specific IgE levels for seven inhalant allergens varied with age in preschool children. Although further investigations are needed with a broad range of ages and various allergens, the distribution of the total and specific serum IgE levels in preschool children might help to serve as a reference value to diagnose atopy.

Racial disparities in allergic outcomes in African Americans emerge as early as age 2 years

BACKGROUND

Racial disparities in allergic disease outcomes have been reported with African Americans suffering disproportionately compared to White individuals.

OBJECTIVE

To examine whether or not racial disparities are present as early as age 2 years in a racially diverse birth cohort in the Detroit metropolitan area.

METHODS

All children who were participants in a birth cohort study in the Detroit metropolitan area were invited for a standardized physician exam with skin prick testing and parental interview at age 2 years. Physicians made inquiries regarding wheezing and allergy symptoms and inspected for and graded any atopic dermatitis (AD). Skin testing was performed for Alternaria, cat, cockroach, dog, Dermatophagoides farinae (Der F), Short Ragweed, Timothy grass, egg, milk and peanut. Specific IgE was measured for these same allergens and total IgE was determined.

RESULTS

African American children (n = 466) were more likely than White children (n = 223) to have experienced any of the outcomes examined: at least 1 positive skin prick test from the panel of 10 allergens (21.7% vs. 11.0%, P = 0.001); at least one specific IgE ≥ 0.35 IU/mL (out of a panel of 10 allergens) (54.0% vs. 42.9%, P = 0.02); had AD (27.0% vs. 13.5%, Chi-square P < 0.001); and to ever have wheezed (44.9% vs. 36.0%, P = 0.03). African American children also tended to have higher total IgE (geometric means 23.4 IU/mL (95%CI 20.8, 27.6) vs. 16.7 IU/mL (95%CI 13.6, 20.6 IU/mL), Wilcoxon Rank Sum P = 0.004). With the exception of wheezing, the associations did not vary after adjusting for common social economic status variables (e.g. household income), environmental variables (endotoxin; dog, cat and cockroach allergen in house dust) or variables that differed between the racial groups (e.g. breastfeeding). After adjustment, the wheeze difference was ameliorated.

CONCLUSIONS

With disparities emerging as early as age 2 years, investigations into sources of the disparities should include the prenatal period and early life.

Spatial Cluster Detection for Longitudinal Outcomes using Administrative Regions

This manuscript proposes a new spatial cluster detection method for longitudinal outcomes that detects neighborhoods and regions with elevated rates of disease while controlling for individual level confounders. The proposed method, CumResPerm, utilizes cumulative geographic residuals through a permutation test to detect potential clusters which are are defined as sets of administrative regions, such as a town, or group of administrative regions. Previous cluster detection methods are not able to incorporate individual level data including covariate adjustment, while still being able to define potential clusters using informative neighborhood or town boundaries. Often it is of interest to detect such spatial clusters because individuals residing in a town may have similar environmental exposures or socioeconomic backgrounds due to administrative reasons, such as zoning laws. Therefore these boundaries can be very informative and more relevant than arbitrary clusters such as the standard circle or square. Application of the CumResPerm method will be illustrated by the Home Allergens and Asthma prospective cohort study analyzing the relationship between area or neighborhood residence and repeated measured outcome, occurrence of wheeze in the last 6 months, while taking into account mobile locations.

A meta-analysis of genome-wide association studies for serum total IgE in diverse study populations

BACKGROUND

IgE is both a marker and mediator of allergic inflammation. Despite reported differences in serum total IgE levels by race-ethnicity, African American and Latino subjects have not been well represented in genetic studies of total IgE.

OBJECTIVE

We sought to identify the genetic predictors of serum total IgE levels.

METHODS

We used genome-wide association data from 4292 subjects (2469 African Americans, 1564 European Americans, and 259 Latinos) in the EVE Asthma Genetics Consortium. Tests for association were performed within each cohort by race-ethnic group (ie, African American, Latino, and European American) and asthma status. The resulting P values were meta-analyzed, accounting for sample size and direction of effect. Top single nucleotide polymorphism associations from the meta-analysis were reassessed in 6 additional cohorts comprising 5767 subjects.

RESULTS

We identified 10 unique regions in which the combined association statistic was associated with total serum IgE levels (P<5.0×10(-6)) and the minor allele frequency was 5% or greater in 2 or more population groups. Variant rs9469220, corresponding to HLA-DQB1, was the single nucleotide polymorphism most significantly associated with serum total IgE levels when assessed in both the replication cohorts and the discovery and replication sets combined (P=.007 and 2.45×10(-7), respectively). In addition, findings from earlier genome-wide association studies were also validated in the current meta-analysis.

CONCLUSION

This meta-analysis independently identified a variant near HLA-DQB1 as a predictor of total serum IgE levels in multiple race-ethnic groups. This study also extends and confirms the findings of earlier genome-wide association analyses in African American and Latino subjects.

Allergic sensitization frequency and wheezing differences in early life between black and white children

Asthma is more common in black children than in white children. Allergic sensitization has been shown to be associated with increased likelihood of asthma. This study was designed to determine whether there are racial differences in the allergens to which children are sensitized in the Detroit metropolitan area and determine whether sensitization was associated with wheeze outcomes. Pregnant women were recruited for the Wayne County Health, Environment, Allergy, and Asthma Longitudinal Study birth cohort to follow the health of their children in the Detroit metropolitan area. Specific IgE (sIgE) was measured for Alternaria, cat, cockroach, dog, Dermatophagoides farinae, short ragweed, timothy grass, egg, milk, and peanut in blood samples from the children at age 2 years. A positive allergen sIgE was defined as ≥0.35 IU/mL. Mothers reported their child's race and completed interviews at age 2 years about characteristics of wheezing episodes in their child (frequency, medication, acute care, or emergency department visit). Black children (n = 384) were more likely than white children (n = 180) to have been positive for each of the allergens tested and also tended to have positive responses to a greater number of allergens (four or more allergens: 9.2% versus 3.5%). Children who had two or more positive sIgEs (adjusted odds ratio [aOR] = 2.68; 95% 95% confidence interval [CI], 1.33, 5.46) or three or more positive sIgEs (aOR = 2.67, 95% CI, 1.19, 6.01) were more likely to have wheezed four or more times in the last 12 months. Racial differences in sensitization at this young age may contribute to the racial difference in asthma prevalence at later ages.

Sensitization and allergic histories differ between black and white pregnant women

BACKGROUND

Racial differences in allergic diseases have been reported, with black subjects suffering disproportionately compared with white subjects, although such studies have been more commonly done in pediatric populations.

OBJECTIVE

We sought to determine whether there are differences in rates of allergic sensitization or prior diagnoses of asthma, hay fever, or eczema in black and white pregnant women.

METHODS

Women were recruited during pregnancy (regardless of allergic history) as part of a birth cohort study in the Detroit metropolitan area and were interviewed about prior doctors' diagnoses of asthma, hay fever/nasal allergies/allergic rhinitis, and eczema. Blood samples were collected, total IgE levels were determined, and specific IgE levels were measured for Alternaria alternata, cat, cockroach, dog, Dermatophagoides farinae, short ragweed, timothy grass, and egg.

RESULTS

Black women (n = 563) were more likely than white women (n = 219) to have had at least 1 specific IgE level of 0.35 IU/mL or greater (62.5% vs 40.2%, P < .001). Black women had higher total IgE levels (geometric mean, 47.8 IU/mL [95% CI, 42.5-53.8 IU/mL] vs 20.0 IU/mL [95% CI, 16.2-24.6 IU/mL]; P < .001, Wilcoxon rank sum test). Black women were more likely to have had a prior doctor's diagnosis of asthma (22.7% vs 16.0%, P = .04) and eczema (21.9% vs 14.8%) but not hay fever (white women: 17.5% vs black women: 15.7%, P = .55). Associations persisted for total IgE levels, having 1 or more positive allergen-specific IgE levels, and eczema after adjusting for common socioeconomic or environmental variables.

CONCLUSIONS

Racial differences in allergic sensitization and diagnoses were present, even after controlling for various factors. Future research should focus on prevention to ameliorate these disparities.

Study protocol for Women of Color and Asthma Control: a randomized controlled trial of an asthma-management intervention for African American women

BACKGROUND

Among adults in the United States, asthma prevalence is disproportionately high among African American women; this group also experiences the highest levels of asthma-linked mortality and asthma-related health care utilization. Factors linked to biological sex (e.g., hormonal fluctuations), gender roles (e.g., exposure to certain triggers) and race (e.g., inadequate access to care) all contribute to the excess asthma burden in this group, and also shape the context within which African American women manage their condition. No prior interventions for improving asthma self-management have specifically targeted this vulnerable group of asthma patients. The current study aims to evaluate the efficacy of a culturally- and gender-relevant asthma-management intervention among African American women.

METHODS/DESIGN

A randomized controlled trial will be used to compare a five-session asthma-management intervention with usual care. This intervention is delivered over the telephone by a trained health educator. Intervention content is informed by the principles of self-regulation for disease management, and all program activities and materials are designed to be responsive to the specific needs of African American women. We will recruit 420 female participants who self-identify as African American, and who have seen a clinician for persistent asthma in the last year. Half of these will receive the intervention. The primary outcomes, upon which the target sample size is based, are number of asthma-related emergency department visits and overnight hospitalizations in the last 12 months. We will also assess the effect of the intervention on asthma symptoms and asthma-related quality of life. Data will be collected via telephone survey and medical record review at baseline, and 12 and 24 months from baseline.

DISCUSSION

We seek to decrease asthma-related health care utilization and improve asthma-related quality of life in African American women with asthma, by offering them a culturally- and gender-relevant program to enhance asthma management. The results of this study will provide important information about the feasibility and value of this program in helping to address persistent racial and gender disparities in asthma outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01117805.

Early complementary feeding and risk of food sensitization in a birth cohort

BACKGROUND

Exposure to solid food or cow's milk (complementary food) before age 4 months may confer immune protection (tolerance) or detriment (allergy).

OBJECTIVE

We explored the relationship between introduction of complementary food <4 months and IgE to egg, milk, and peanut allergen at 2 years in the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study birth cohort of Detroit, Mich.

METHODS

At infant ages 1, 6, and 12 months, mothers were interviewed about feeding practices. Blood samples were collected at age 2 to 3 years to assess sensitization (IgE ≥ 0.35 IU/mL) to egg, milk, or peanut.

RESULTS

For the 594 maternal-infant pairs analyzed, maternal mean age was 29.7 years, and 60.6% self-reported as African American or black. Infant exposure to complementary food <4 months was reported by 39.7% of mothers. IgE ≥0.35 IU/mL for egg, milk, or peanut allergen at age 2 years was observed in 23.9% (95% CI, 20.5% to 27.6%), 30.6% (26.9% to 34.5%), and 11.4% (8.9% to 14.3%) of children, respectively. The association between early feeding and sensitization was modified by parental history of asthma or allergy. In multivariable analysis, early feeding reduced the risk of peanut sensitization among children with a parental history (adjusted odds ratio, 0.2 [95% CI, 0.1-0.7]; P = .007). The relationship also became significant for egg when a cutoff for IgE of ≥0.70 IU/mL was used (adjusted odds ratio, 0.5 [95% CI, 0.3-0.9]; P = .022).

CONCLUSION

In this cohort, complementary food introduced <4 months was associated with a reduced risk of peanut (and perhaps egg) sensitization by age 2 to 3 years, but only for children with a parental history of asthma or allergy.