Does eczema lead to asthma?

No remission in 60% of those with childhood-onset asthma - A population-based cohort followed from 8 to 28 years of age

BACKGROUND

Although remission occur, childhood-onset asthma may persist until adulthood. Since few longitudinal population-based studies have followed a cohort from childhood until adulthood, the knowledge on predictors of persistence of asthma is sparse.

AIM

To estimate persistence of asthma from 8 to 28 years and its associated factors.

METHODS

Within the OLIN (Obstructive Lung Disease in Northern Sweden) studies, a cohort was recruited in 1996 (age 8y, n = 3430) and followed annually with questionnaires about asthma and risk factors until 19y. Clinical examinations included skin prick tests (at 8, 12 and 19y) and lung function tests (17 and 19y) whereof a subsample performed bronchial hyperreactivity test. We identified n = 248 with asthma at 8y whereof 170 (69%) participated in a follow-up at 28y (73% of possible to invite).

RESULTS

Of the 170 participants at 28y, 105 (61.8%) had persistent asthma (women: 49/76, 64.5%; men: 56/94, 59.6%, p = 0.513). Factors collected at recruitment: allergic sensitization (OR7.8, 95%CI 3.0-20.2), severe respiratory infection (OR2.6, 95%CI 1.1-6.3) and higher asthma severity score (OR1.6, 95%CI 1.1-2.4) were associated with asthma at 28y after adjustment for sex, family history of asthma, breastfeeding <3 months and eczema. Replacing allergic sensitization with rhinoconjunctivitis in the model yielded OR3.4 (95%CI 1.5-8.0). Bronchial hyperreactivity at age 17y associated with asthma at 28y (OR9.0, 95%CI 1.7-47.0).

CONCLUSIONS

Among children with asthma onset by 8y, 62% still had asthma at age 28 years. Persistent asthma was associated with allergic sensitization, rhinoconjunctivitis, severe respiratory infection, a more severe asthma and bronchial hyperreactivity.

Familial aggregation of multimorbidity in Sweden: national explorative family study

Objectives

To examine whether multimorbidity aggregates in families in Sweden.

Design

National explorative family study.

Setting

Swedish Multigeneration Register linked to the National Patient Register, 1997-2015. Multimorbidity was assessed with a modified counting method of 45 chronic non-communicable diseases according to ICD-10 (international classification of diseases, 10th revision) diagnoses.

Participants

2 694 442 Swedish born individuals (48.73% women) who could be linked to their Swedish born first, second, and third degree relatives. Twins were defined as full siblings born on the same date.

Main outcome measures

Multimorbidity was defined as two or more non-communicable diseases. Familial associations for one, two, three, four, and five or more non-communicable diseases were assessed to examine risks depending on the number of non-communicable diseases. Familial adjusted odds ratios for multimorbidity were calculated for individuals with a diagnosis of multimorbidity compared with relatives of individuals unaffected by multimorbidity (reference). An initial principal component decomposition followed by a factor analysis with a principal factor method and an oblique promax rotation was used on the correlation matrix of tetrachoric correlations between 45 diagnoses in patients to identify disease clusters.

Results

The odds ratios for multimorbidity were 2.89 in twins (95% confidence interval 2.56 to 3.25), 1.81 in full siblings (1.78 to 1.84), 1.26 in half siblings (1.24 to 1.28), and 1.13 in cousins (1.12 to 1.14) of relatives with a diagnosis of multimorbidity. The odds ratios for multimorbidity increased with the number of diseases in relatives. For example, among twins, the odds ratios for multimorbidity were 1.73, 2.84, 4.09, 4.63, and 6.66 for an increasing number of diseases in relatives, from one to five or more, respectively. Odds ratios were highest at younger ages: in twins, the odds ratio was 3.22 for those aged ≤20 years, 3.14 for those aged 21-30 years, and 2.29 for those aged >30 years at the end of follow-up. Nine disease clusters (factor clusters 1-9) were identified, of which seven aggregated in families. The first three disease clusters in the principal component decomposition were cardiometabolic disease (factor 1), mental health disorders (factor 2), and disorders of the digestive system (factor 3). Odds ratios for multimorbidity in twins, siblings, half siblings, and cousins for the factor 1 cluster were 2.79 (95% confidence interval 0.97 to 8.06), 2.62 (2.39 to 2.88), 1.52 (1.34 to 1.73), and 1.31 (1.23 to 1.39), and for the factor 2 cluster, 5.79 (4.48 to 7.48) 3.24 (3.13 to 3.36), 1.51 (1.45 to 1.57), and 1.37 (1.341.40).

Conclusions

The results of this explorative family study indicated that multimorbidity aggregated in Swedish families. The findings suggest that map clusters of diseases should be used for the genetic study of common diseases to show new genetic patterns of non-communicable diseases.

Immunotherapy in the Treatment of Allergic Rhinitis in Children

Allergic rhinitis (AR) is an inflammation of the nasal membranes characterized by multiple allergic symptoms. It is a widespread health problem that affects patients' ability to engage in social and physical activity, which lowers their quality of life. The pathophysiology of AR is complex and requires sensitization and the development of a specific immune response to the allergen. Allergen-specific immunotherapy (AIT) is a therapeutic method that induces specific immune tolerance to allergens. The objectives of this review are to demonstrate the mechanism of action of immunotherapy, explain how it alleviates clinical symptoms of allergic rhinitis, list the indications and contraindications of immunotherapy in the treatment of allergic rhinitis, and identify different modalities of allergen immunotherapy, their disease-modifying effects, as well as their potential risks and benefits. The review of the literature highlights that T-cell and B-cell responses to inhaled allergens are altered by AIT, which decreases both early and late reactions to allergen exposure. To induce clinical and immunologic tolerance, especially in the pediatric age, escalating dosages of the causing allergen are administered subcutaneously or sublingually. AIT is indicated for severe persistent AR when avoidance measures and medications are inadequate to control the symptoms. To conclude, AIT is a disease-modifying therapy that is safe and effective for the treatment of allergic rhinitis. It is indicated when the symptoms are uncontrolled or when there are undesirable effects from pharmacotherapy.

The clinical burden of cow's milk allergy in early childhood: A retrospective cohort study

Introduction

Cow's milk allergy (CMA) is common in infants and children. Clinical presentations may vary, with a range of symptoms affecting the gastrointestinal (GI), skin and respiratory systems. Whilst the primary focus of research to date has been on the management of these symptoms, studies investigating the broader clinical burden of CMA are limited.

Methods

We performed a retrospective matched cohort study examining clinical data, including allergic symptoms and infections, extracted from case records within The Health Improvement Network database. A total of 6998 children (54% male) were included in the study, including 3499 with CMA (mean age at diagnosis 4.04 months) and 3499 matched controls without CMA, observed for a mean period of 4.2 years.

Results

GI, skin and respiratory symptoms affected significantly more children with CMA (p < .001), which recurred more often (p < .001), compared with children without CMA. More children with CMA had symptoms affecting multiple systems (p < .001). CMA was associated with a greater probability of these symptoms requiring hypoallergenic formula (HAF) prescription persisting over time (log‐rank test p < .0001, unadjusted hazard ratio [HR]: 0.81, 95% confidence interval [CI]: 0.76–0.85, p < .001), with a longer median duration of symptoms and HAF prescription compared with the duration of symptoms in those without CMA (3.48 vs. 2.96 years). GI, skin, respiratory and ear infections affected significantly more children with CMA than those without, increasing by 74% (p < .001), 20% (p < .001), 9% (p < .001), and 30% (p < .001) respectively. These infections also recurred more often among children with CMA, increasing by 62% for GI infections, 37% for skin and respiratory infections, and 44% for ear infections (p < .001).

Conclusions

This real‐world study provides evidence to suggest that CMA presents a significant clinical burden to children, which has implications for the healthcare system. Further research is warranted to understand the health economic impact of this, and the phenotypes, factors and management approaches which may affect clinical outcomes.

Halting the March: Primary Prevention of Atopic Dermatitis and Food Allergies

Atopic dermatitis (AD) is one of the most common inflammatory skin conditions, affecting 15% to 30% of children and 2% to 10% of adults. Population-based studies suggest that having AD is associated with subsequent development of other atopic diseases, in what is known as the "atopic march." We will provide an overview of studies that investigate primary prevention strategies for the first 2 diseases in the march, namely, AD and food allergies (FA). These strategies include emollients, breastfeeding, microbial exposures, probiotics, vitamin D and UV light, water hardness, and immunotherapy. Some studies, including randomized controlled trials on emollients and microbial supplementation, have found encouraging results; however, the evidence remains limited and contradictory. With regard to breastfeeding, microbial and lifestyle exposures, vitamin D and UV light, water hardness, and immunotherapy, the lack of randomized controlled trials makes it difficult to draw definitive conclusions. Current American Academy of Pediatrics guidelines support the idea that breastfeeding for 3 to 4 months can decrease AD incidence in children less than 2 years old. Recommendations regarding a direct relationship between breastfeeding on FA, however, cannot be made because of insufficient data. Regarding microbial supplementation, most guidelines do not recommend probiotics or prebiotics for the purpose of preventing allergic diseases because of limited evidence. Before definitive conclusions can be made regarding these interventions, more well-designed, longitudinal, and randomized controlled trials, particularly in at-risk populations, are required.

Atopic phenotypes and their implication in the atopic march

INTRODUCTION

Eczema, allergic rhinitis, and asthma are traditionally considered atopic (or allergic) diseases. They are complex, multifactorial, and are caused by a variety of different mechanisms, which result in multiple heterogeneous clinical phenotypes. Atopic march is usually interpreted as the sequential development of symptoms from eczema in infancy, to asthma, and then allergic rhinitis. Areas covered: The authors reviewed the evidence on the multimorbidity of eczema, asthma, and rhinitis, and the implication of results of data-driven analyses on the concept framework of atopic march. A literature search was conducted in the PubMed and Web of Science for peer-reviewed articles published until July 2020. Application of Bayesian machine learning framework to rich phenotypic data from birth cohorts demonstrated that the postulated linear progression of symptoms (atopic march) does not capture the heterogeneity of allergic phenotypes. Expert opinion: Eczema, wheeze, and rhinitis co-exist more often than would be expected by chance, but their relationship can be best understood in a multimorbidity framework, rather than through atopic march sequence. The observation of their co-occurrence does not imply any specific relationship between them, and certainly not a progressive or causal one. It is unlikely that a sngle mechanism such as allergic sensitization underpins different multimorbidity manifestations.

Research Progress in Atopic March

The incidence of allergic diseases continues to rise. Cross-sectional and longitudinal studies have indicated that allergic diseases occur in a time-based order: from atopic dermatitis and food allergy in infancy to gradual development into allergic asthma and allergic rhinitis in childhood. This phenomenon is defined as the “atopic march”. Some scholars have suggested that the atopic march does not progress completely in a temporal pattern with genetic and environmental factors. Also, the mechanisms underlying the atopic march are incompletely understood. Nevertheless, the concept of the atopic march provides a new perspective for the mechanistic research, prediction, prevention, and treatment of atopic diseases. Here, we review the epidemiology, related diseases, mechanistic studies, and treatment strategies for the atopic march.

Deserters on the atopic march: Risk factors, immune profile and clinical outcomes of food sensitized-tolerant infants

BACKGROUND

A few studies have investigated the antecedents and outcomes of infants who demonstrate IgE sensitization to foods that they clinically tolerate. Improved understanding of this sensitized-tolerant phenotype may inform strategies for the prevention of food allergy.

METHODS

In an Australian birth cohort (n = 1074), assembled using an unselected antenatal sampling frame, participants were categorized as nonsensitized (NS), sensitizedtolerant (ST), or food allergic (FA) based on skin prick testing and food challenge at 12 months of age. Environmental exposures were recorded throughout. Cord blood regulatory T-cell populations were measured at birth. Subsequent childhood allergic disease was assessed by parent report, clinical examination, and repeat skin prick testing.

RESULTS

The covariates of interest varied between NS (n = 698), ST (n = 27), and FA (n = 61) groups as follows, suggesting that across these measures, the ST group was more similar to the NS than the FA group: family history of eczema NS 44.6%, ST. 44.6%, FA 65.6%; pet ownership at 12 months: NS 71.5%, ST 81.5%, FA 45.8%; eczema during the first 12 months: NS 19%, ST 32%, FA 64%; and aeroallergen sensitization at 4 years: NS 19.1%, ST 28.6%, FA 44.4%. At birth, a higher proportion of activated regulatory T cells was associated with ST (OR = 2.89, 95% CI 1.03-8.16, P = .045).

CONCLUSION

Food-sensitized-tolerance in infancy appears to be associated with a similar pattern of exposures, immunity, and outcomes to nonsensitized infants. In addition, we found some evidence that an elevated proportion of activated regulatory T cells at birth was specific to the sensitized-tolerant infants, which may be relevant to suppression of clinical disease.

Disease trajectories in childhood atopic dermatitis: an update and practitioner's guide

BACKGROUND

Atopic dermatitis (AD) is a heterogeneous disease with a multifactorial aetiology and complex pathophysiology. This heterogeneity translates into different trajectories of disease progression with respect to severity, persistence and risk of development of atopic comorbidities. Determining which possible disease trajectories or comorbidities any individual child might develop is challenging in clinical practice. Tools that help identify paediatric patients at higher risk of disease progression would greatly aid clinicians.

METHODS

We reviewed recent cohort studies to synthesize and simplify the epidemiological data to try to identify shared clinically relevant characteristics that may help physicians estimate the risk of disease progression in paediatric patients with AD.

RESULTS

Despite the variability in data collection and methods of analysis and their limitations, there are common patterns of early-childhood AD that may aid in the estimation of risk for disease progression. Factors associated with risk of AD progression include younger age of onset, family history of atopy, greater AD severity, filaggrin mutations, urban environment and polysensitization and/or allergic multimorbidity. Based on these factors, we provide a practitioner's guide for identifying, counselling and/or referring infants and children with AD at potentially higher risk of developing persistent AD and atopic comorbidities. We also present clinical scenarios to illustrate how these data relate to real-life situations.

CONCLUSIONS

Useful insights are provided for physicians and patients to inform them better about the risk of AD progression and to help guide care pathways for the paediatric population with AD. What's already known about this topic? The complex pathophysiology of atopic dermatitis (AD) translates into a heterogeneous clinical presentation and trajectories of disease progression. Although the consensus is that most paediatric patients with AD will eventually 'outgrow' the disease or follow the longitudinal trajectory known as the 'atopic march', a significant proportion will develop persistent AD and/or other atopic conditions. No known factors conclusively predict the risk of progression or development of comorbidities. What does this study add? Recent analyses of data from large cohorts of paediatric patients with AD have suggested the existence of potentially discrete clusters of patients who present with relatively common AD phenotypes. These studies have shed some light onto the factors associated with risk of progression, which we review in this article. A practitioner's guide with clinical scenarios is provided to help identify patients at high risk of progression to determine whether a patient should be monitored and/or would require specialist referral.

Milk Other Than Breast Milk and the Development of Asthma in Children 3 Years of Age. A Birth Cohort Study (2006⁻2011)

Prevalence of asthma in Australian children is amongst the highest in the world. Although breastfeeding positively influences infant immunity, early introduction of Milk Other than Breast Milk (MOTBM) may also play an important role in the development of Asthma. The aim of this study was to investigate the association between the introduction of MOTBM in the first six months after birth and the development of reported persistent asthma in 3-year olds. A sample of 1121 children was extracted from the Environments for Healthy Living longitudinal birth cohort study. Introduction of MOTBM during the first six months after birth increased almost two-fold the risk of development of persistent asthma after adjusting for other covariates (Adjusted Relative Risk (ARR): 1.71, 95% CI: 1.03⁻2.83, p = 0.038). This study indicates that the introduction of MOTBM in the first six months of life is a risk factor for asthma incidence among 3-year old children. This result is important in explaining the benefits of breastfeeding as part of public health interventions to encourage mothers to increase breastfeeding initiation and duration, and avoid the introduction of MOTBM in the first six months after childbirth.

Predicting the atopic march: Results from the Canadian Healthy Infant Longitudinal Development Study

BACKGROUND

The atopic march describes the progression from atopic dermatitis during infancy to asthma and allergic rhinitis in later childhood. In a Canadian birth cohort we investigated whether concomitant allergic sensitization enhances subsequent development of these allergic diseases at age 3 years.

METHODS

Children completed skin prick testing at age 1 year. Children were considered sensitized if they produced a wheal 2 mm or larger than that elicited by the negative control to any of 10 inhalant or food allergens. Children were also assessed for atopic dermatitis by using the diagnostic criteria of the UK Working Party. At age 3 years, children were assessed for asthma, allergic rhinitis, food allergy, and atopic dermatitis. Data from 2311 children were available.

RESULTS

Atopic dermatitis without allergic sensitization was not associated with an increased risk of asthma at age 3 years after adjusting for common confounders (relative risk [RR], 0.46; 95% CI, 0.11-1.93). Conversely, atopic dermatitis with allergic sensitization increased the risk of asthma more than 7-fold (RR, 7.04; 95% CI, 4.13-11.99). Atopic dermatitis and allergic sensitization had significant interactions on both the additive (relative excess risk due to interaction, 5.06; 95% CI, 1.33-11.04) and multiplicative (ratio of RRs, 5.80; 95% CI, 1.20-27.83) scales in association with asthma risk. There was also a positive additive interaction between atopic dermatitis and allergic sensitization in their effects on food allergy risk (relative excess risk due to interaction, 15.11; 95% CI, 4.19-35.36).

CONCLUSIONS

Atopic dermatitis without concomitant allergic sensitization was not associated with an increased risk of asthma. In combination, atopic dermatitis and allergic sensitization had strong interactive effects on both asthma and food allergy risk at age 3 years.

A mechanistic target of rapamycin complex 1/2 (mTORC1)/V-Akt murine thymoma viral oncogene homolog 1 (AKT1)/cathepsin H axis controls filaggrin expression and processing in skin, a novel mechanism for skin barrier disruption in patients with atopic dermatitis

BACKGROUND

Filaggrin, which is encoded by the filaggrin gene (FLG), is an important component of the skin's barrier to the external environment, and genetic defects in FLG strongly associate with atopic dermatitis (AD). However, not all patients with AD have FLG mutations.

OBJECTIVE

We hypothesized that these patients might possess other defects in filaggrin expression and processing contributing to barrier disruption and AD, and therefore we present novel therapeutic targets for this disease.

RESULTS

We describe the relationship between the mechanistic target of rapamycin complex 1/2 protein subunit regulatory associated protein of the MTOR complex 1 (RAPTOR), the serine/threonine kinase V-Akt murine thymoma viral oncogene homolog 1 (AKT1), and the protease cathepsin H (CTSH), for which we establish a role in filaggrin expression and processing. Increased RAPTOR levels correlated with decreased filaggrin expression in patients with AD. In keratinocyte cell cultures RAPTOR upregulation or AKT1 short hairpin RNA knockdown reduced expression of the protease CTSH. Skin of CTSH-deficient mice and CTSH short hairpin RNA knockdown keratinocytes showed reduced filaggrin processing, and the mouse had both impaired skin barrier function and a mild proinflammatory phenotype.

CONCLUSION

Our findings highlight a novel and potentially treatable signaling axis controlling filaggrin expression and processing that is defective in patients with AD.

IgE antibodies in relation to prevalence and multimorbidity of eczema, asthma, and rhinitis from birth to adolescence

BACKGROUND

Eczema, asthma, and rhinitis affect a large proportion of children, but their prevalence varies with age. IgE antibodies are also common in the pediatric population. However, the links between IgE, disease, and trajectories are unclear.

OBJECTIVE

To better understand the links between sensitization and disease, we studied IgE sensitization ever in relation to eczema, asthma, and rhinitis, in children followed up to 16 years of age.

METHODS

From the Swedish population-based birth cohort BAMSE, 2607 children were included. Parental reports from six time points between 1 and 16 years were used to identify children with eczema, asthma, and rhinitis. Blood was collected at 4, 8, and 16 years, and sensitization ever was defined as allergen-specific IgE ≥0.35 kUA /l to common food and/or inhalant allergens at any time point. Odds ratios for eczema, asthma, rhinitis, and multimorbidity in relation to sensitization ever were calculated using generalized estimating equations.

RESULTS

Fifty-one percent were sensitized at least once up to 16 years. Almost a quarter of ever-sensitized children did not have any disease. After adjustment for potential confounders, sensitization ever was significantly associated with the following: (i) eczema throughout childhood, (ii) multimorbidity of eczema, asthma, and rhinitis from 1 to 16 years (OR for multimorbidity: 5.11, 95% CI: 3.99-6.55), (iii) asthma and rhinitis from 4 to 16 years of age.

CONCLUSIONS

Specific IgE is strongly associated with eczema and allergic multimorbidity throughout childhood and with asthma and rhinitis from age 4 years. However, 23% of the children with IgE sensitization do not develop any disease in childhood.

The march from early life food sensitization to allergic disease: a systematic review and meta-analyses of birth cohort studies

BACKGROUND

There is growing evidence for an increase in food allergies. The question of whether early life food sensitization, a primary step in food allergies, leads to other allergic disease is a controversial but important issue. Birth cohorts are an ideal design to answer this question.

OBJECTIVES

We aimed to systematically investigate and meta-analyse the evidence for associations between early food sensitization and allergic disease in birth cohorts.

METHODS

MEDLINE and SCOPUS databases were searched for birth cohorts that have investigated the association between food sensitization in the first 2 years and subsequent wheeze/asthma, eczema and/or allergic rhinitis. We performed meta-analyses using random-effects models to obtain pooled estimates, stratified by age group.

RESULTS

The search yielded fifteen original articles representing thirteen cohorts. Early life food sensitization was associated with an increased risk of infantile eczema, childhood wheeze/asthma, eczema and allergic rhinitis and young adult asthma. Meta-analyses demonstrated that early life food sensitization is related to an increased risk of wheeze/asthma (pooled OR 2.9; 95% CI 2.0-4.0), eczema (pooled OR 2.7; 95% CI 1.7-4.4) and allergic rhinitis (pooled OR 3.1; 95% CI 1.9-4.9) from 4 to 8 years.

CONCLUSION

Food sensitization in the first 2 years of life can identify children at high risk of subsequent allergic disease who may benefit from early life preventive strategies. However, due to potential residual confounding in the majority of studies combined with lack of follow-up into adolescence and adulthood, further research is needed.

Atopic Dermatitis and Respiratory Allergy: What is the Link

Understanding the aetiology and progression of atopic dermatitis and respiratory allergy may elucidate early preventative and management strategies aimed towards reducing the global burden of asthma and allergic disease. In this article, we review the current opinion concerning the link between atopic dermatitis and the subsequent progression of respiratory allergies during childhood and into early adolescence. Advances in machine learning and statistical methodology have facilitated the discovery of more refined definitions of phenotypes for identifying biomarkers. Understanding the role of atopic dermatitis in the development of respiratory allergy may ultimately allow us to determine more effective treatment strategies, thus reducing the patient and economic burden associated with these conditions.

The perception of allergen-specific immunotherapy among pediatricians in the primary care setting

BACKGROUND

Allergic respiratory diseases are constantly increasing in prevalence. Allergen Immunotherapy (AIT) represent a valuable therapeutic tool as symptomatic and preventative approach, expecially in children. In Italy, primary care pediatricians (PCP) represent the first-line contact and interface for prescription, use and management of AIT. We attempted to evaluate the perception of AIT practice among PCP.

METHODS

A questionnaire was built-up, based on literature, guidelines and with the contribution of pediatricians. The questionnaire, including 12 items, was e-mailed to 180 PCP, randomly chosen from mailing lists. The questionnaire explored the personal perception of AIT, the comparison between subcutaneous and sublingual AIT and the overall awareness about the treatment.

RESULTS

130 questionnaires were eligible for analysis. There was a satisfactory knowledge of the characteristics of AIT, its aims and limits, although the positioning of the treatment in guidelines was insufficiently known. Overall, the prescription of AIT made by other specialists was accepted and agreed (78 %). The majority of pediatricians felt that a more intense divulgation and information about AIT would be needed (90 %).

CONCLUSION

AIT is in general well known and accepted among PCP, although a more intense divulgation effort is required.

Interrelationships between Atopic Disorders in Children: A Meta-Analysis Based on ISAAC Questionnaires

Purpose

To study the prevalence and interrelationship between asthma, allergic rhinitis and eczema using data obtained from ISAAC questionnaires.

Method

The Medline, Pubmed Publisher, EMBASE, Google Scholar and the Cochrane Controlled Clinical Trials Register databases were systematically reviewed to evaluate epidemiological data of children with atopic disorders. To study these interrelationships, a new approach was used. Risk ratios were calculated, describing the risk of having two different atopic disorders when the child is known with one disorder.

Results

Included were 31 studies, covering a large number of surveyed children (n=1,430,329) in 102 countries. The calculated worldwide prevalence for asthma, eczema and allergic rhinitis is 12.00% (95% CI: 11.99-12.00), 7.88% (95% CI: 7.88-7.89) and 12.66% (95% CI: 12.65-12.67), respectively. The observed prevalence [1.17% (95% CI: 1.17-1.17)] of having all three diseases is 9.8 times higher than could be expected by chance. For children with asthma the calculated risk ratio of having the other two disorders is 5.41 (95% CI: 4.76-6.16), for children with eczema 4.24 (95% CI: 3.75-4.79), and for children with allergic rhinitis 6.20 (95% CI: 5.30-7.27). No studied confounders had a significant influence on these risk ratios.

Conclusions

Only a minority of children suffers from all three atopic disorders, however this co-occurrence is significantly higher than could be expected by chance and supports a close relationship of these disorders in children. The data of this meta-analysis supports the hypothesis that there could be a fourth distinct group of children with all three disorders. Researchers and clinicians might need to consider these children as a separate group with distinct characteristics regarding severity, causes, treatment or prognosis.

Developmental profiles of eczema, wheeze, and rhinitis: two population-based birth cohort studies

BACKGROUND

The term "atopic march" has been used to imply a natural progression of a cascade of symptoms from eczema to asthma and rhinitis through childhood. We hypothesize that this expression does not adequately describe the natural history of eczema, wheeze, and rhinitis during childhood. We propose that this paradigm arose from cross-sectional analyses of longitudinal studies, and may reflect a population pattern that may not predominate at the individual level.

METHODS AND FINDINGS

Data from 9,801 children in two population-based birth cohorts were used to determine individual profiles of eczema, wheeze, and rhinitis and whether the manifestations of these symptoms followed an atopic march pattern. Children were assessed at ages 1, 3, 5, 8, and 11 y. We used Bayesian machine learning methods to identify distinct latent classes based on individual profiles of eczema, wheeze, and rhinitis. This approach allowed us to identify groups of children with similar patterns of eczema, wheeze, and rhinitis over time. Using a latent disease profile model, the data were best described by eight latent classes: no disease (51.3%), atopic march (3.1%), persistent eczema and wheeze (2.7%), persistent eczema with later-onset rhinitis (4.7%), persistent wheeze with later-onset rhinitis (5.7%), transient wheeze (7.7%), eczema only (15.3%), and rhinitis only (9.6%). When latent variable modelling was carried out separately for the two cohorts, similar results were obtained. Highly concordant patterns of sensitisation were associated with different profiles of eczema, rhinitis, and wheeze. The main limitation of this study was the difference in wording of the questions used to ascertain the presence of eczema, wheeze, and rhinitis in the two cohorts.

CONCLUSIONS

The developmental profiles of eczema, wheeze, and rhinitis are heterogeneous; only a small proportion of children (∼ 7% of those with symptoms) follow trajectory profiles resembling the atopic march. Please see later in the article for the Editors' Summary.

Exploring the origins of asthma: Lessons from twin studies

This thesis explores the contribution of twin studies, particularly those studies originating from the Danish Twin Registry, to the understanding of the aetiology of asthma. First, it is explored how twin studies have established the contribution of genetic and environmental factors to the variation in the susceptibility to asthma, and to the variation in several aspects of the clinical expression of the disease such as its age at onset, its symptomatology, its intermediate phenotypes, and its relationship with other atopic diseases. Next, it is explored how twin studies have corroborated theories explaining asthma's recent increase in prevalence, and last, how these fit with the explanations of the epidemiological trends in other common chronic diseases of modernity.

Severe eczema in infancy can predict asthma development. A prospective study to the age of 10 years

BACKGROUND

Children with atopic eczema in infancy often develop allergic rhinoconjunctivitis and asthma, but the term "atopic march" has been questioned as the relations between atopic disorders seem more complicated than one condition progressing into another.

OBJECTIVE

In this prospective multicenter study we followed children with eczema from infancy to the age of 10 years focusing on sensitization to allergens, severity of eczema and development of allergic airway symptoms at 4.5 and 10 years of age.

METHODS

On inclusion, 123 children were examined. Hanifin-Rajka criteria and SCORAD index were used to describe the eczema. Episodes of wheezing were registered, skin prick tests and IgE tests were conducted and questionnaires were filled out. Procedures were repeated at 4.5 and 10 years of age with additional examinations for ARC and asthma.

RESULTS

94 out of 123 completed the entire study. High SCORAD points on inclusion were correlated with the risk of developing ARC, (B = 9.86, P = 0.01) and asthma, (B = 10.17, P = 0.01). For infants with eczema and wheezing at the first visit, the OR for developing asthma was 4.05(P = 0.01). ARC at 4.5 years of age resulted in an OR of 11.28(P = 0.00) for asthma development at 10 years.

CONCLUSION

This study indicates that infant eczema with high SCORAD points is associated with an increased risk of asthma at 10 years of age. Children with eczema and wheezing episodes during infancy are more likely to develop asthma than are infants with eczema alone. Eczema in infancy combined with early onset of ARC seems to indicate a more severe allergic disease, which often leads to asthma development. The progression from eczema in infancy to ARC at an early age and asthma later in childhood shown in this study supports the relevance of the term "atopic march", at least in more severe allergic disease.

The relationships between ambient air pollutants and childhood asthma and eczema are modified by emotion and conduct problems

PURPOSE

This study examined the hypothesis that emotion and conduct problems (ECPs) may modify the relationships between ambient air pollutants and childhood asthma and eczema.

METHODS

In the cross-sectional study, 4209 French schoolchildren (aged 10e12 years) were investigated between March 1999 and October 2000. Ambient air pollutants exposures were estimated with dispersion modeling. Health outcomes and ECPs were evaluated by validated questionnaires, completed by the parents. Marginal models were used to analyze the relationships of exposures to ambient air pollutants and/or ECPs to asthma phenotypes and current eczema, adjusting for potential confounders.

RESULTS

In our population, interactions were found between ECPs and exposures to ambient air pollutants (benzene, carbon monoxide, nitrogen dioxide, nitrogen oxides, particulate matter with an aerodynamic diameter below 10 mm, volatile organic compounds) (P < .20). In addition, ECPs were related to current wheezing (adjusted prevalence odds ratio [aOR], 2.35; 95% confidence interval [CI], 1.59e3.47), current doctor-diagnosed asthma (aOR, 1.82; 95% CI, 1.25e2.66), and current eczema (aOR, 2.21; 95% CI, 1.61e3.02). Children with ECPs had 1.17e1.51 times higher aORs for the associations between ambient air pollutants and asthma phenotypes and current eczema than those without ECPs.

CONCLUSIONS

ECPs may modify the relationships between ambient air pollutants and childhood asthma and eczema.

Early-life risk factors for childhood wheeze phenotypes in a high-risk birth cohort

OBJECTIVE

To define longitudinal childhood wheeze phenotypes and identify their early-life risk factors.

STUDY DESIGN

Current wheeze was recorded 23 times up to age 7 years in a birth cohort at high risk for allergy (n = 620). Latent class analysis of wheeze responses identified 5 classes. Multinomial logistic regression estimated associations of probability-weighted wheezing classes with early-life factors. All phenotypes were compared with never/infrequent wheezers.

RESULTS

Lower respiratory tract infection (LRTI) by 1 year (relative risk [RR], 3.00; 95% CI, 1.58-5.70), childcare by 1 year (RR, 1.51; 95% CI, 1.02-2.22), and higher body mass index (RR, 2.51; 95% CI, 1.09-5.81) were associated with increased risk of early transient wheeze, whereas breastfeeding was protective (RR, 0.54; 95% CI, 0.32-0.90). LRTI (RR, 6.54; 95% CI, 2.55-16.76) and aeroallergen sensitization (RR, 4.95; 95% CI, 1.74-14.02) increased the risk of early persistent wheeze. LRTI (RR, 5.31; 95% CI, 2.71-10.41), eczema (RR, 2.77; 95% CI, 1.78-4.31), aeroallergen sensitization (RR, 5.60; 95% CI, 2.86-10.9), and food sensitization (RR, 2.77; 95% CI, 1.56-4.94) increased the risk of intermediate-onset wheeze, whereas dog exposure at baseline (RR, 0.52; 95% CI, 0.32-0.84) and first-born status (RR, 0.49; 95% CI, 0.32-0.76) were protective. Heavy parental smoking at birth (RR, 3.18; 95% CI, 1.02-9.88) increased the risk of late-onset wheeze, whereas breastfeeding reduced it (RR, 0.34; 95% CI, 0.12-0.96). All wheeze classes except early transient had greater risk of wheeze at age 12 years compared with never/infrequent wheezers.

CONCLUSION

We found distinct early-life risk factor profiles for each wheeze phenotype. These findings provide insight into possible wheeze mechanisms and have implications for identifying preventive strategies and addressing clinical management of early-life wheeze.

Atopic dermatitis and the atopic march revisited

Atopic dermatitis (AD) has become a significant public health problem because of increasing prevalence, together with increasing evidence that it may progress to other allergic phenotypes. While it is now acknowledged that AD commonly precedes other allergic diseases, a link termed 'the atopic march', debate continues as to whether this represents a causal relationship. An alternative hypothesis is that this association may be related to confounding by familial factors or phenotypes that comanifest, such as early-life wheeze and sensitization. However, there is increasing evidence from longitudinal studies suggesting that the association between AD and other allergies is independent of confounding by comanifest allergic phenotypes. The hypotheses on plausible biological mechanisms for the atopic march focus on defective skin barrier function and overexpression of inflammatory mediators released by the skin affected by AD (including thymic stromal lymphopoietin). Both human and animal studies have provided evidence supporting these potential biological mechanisms. Evidence from prevention trials is now critical to establishing a causal nature of the atopic march. An emerging area of research is investigation into environmental modifiers of the atopic march. Such information will assist in identifying secondary prevention strategies to arrest the atopic march. Despite much research into the aetiology of allergies, little progress has been made in identifying effective strategies to reduce the burden of allergic conditions. In this context, the atopic march remains a promising area of investigation.

Chronic pruritus associated with dermatologic disease in infancy and childhood: update from an interdisciplinary group of dermatologists and pediatricians

An effective treatment strategy for chronic pruritus in children with dermatologic disorders should consider the multidimensional aspects of pruritus, the unique challenges associated with treating pruritic skin disorders in the pediatric population, and evidence-based therapies with demonstrated antipruritic benefits and clinically relevant effects on patient/family quality of life (QoL). The Course of Advanced Learning for the Management of ITch (CALM-IT) Task Force is an interdisciplinary group of experts specializing in core aspects of pruritus treatment, integrating pediatrics, dermatology, psychotherapy, pruritus management, and sleep. CALM-IT recently convened to provide updated guidance on managing chronic pruritus associated with dermatologic diseases in pediatric patients, with a special focus on atopic dermatitis (AD) and chronic spontaneous urticaria (csU). This review highlights the updated concepts and best practices, which were built upon international PRACTALL consensus and modified for children and infants with AD and csU. CALM-IT supports the routine use of basic skin therapy and the escalation of topical medications, according to severity and focused on rapid itch control. Anti-inflammatory agents should be appropriate for infants and children (i.e., with an optimized therapeutic index) and have proven antipruritic properties, such as those demonstrated by methylprednisolone aceponate. New experimental findings do not support the use of non-sedating oral antihistamines as adjuvant antipruritic therapy for AD. In csU, oral H1 -antihistamine use is justified, consistent with the distinct pathophysiologic mechanisms of itch underlying AD and csU. All encompassing QoL assessments should consider the burden of both patient and caregiver and should address outstanding unmet clinical needs of pediatric patients. Future research areas include integrated QoL assessments and multidisciplinary treatment programs with pediatric-targeted pruritic therapies providing rapid itch control.

Prevalence and co-occurrence of parentally reported possible asthma and allergic manifestations in pre-school children

Background

The aim of this study was to make an in-depth analysis of the prevalence and co-occurrence in pre-school children of possible asthma and atopic manifestations.

Methods

In Sweden 74%-84% of preschool children, depending on age, attend municipality organised day-care centres. Parents of 5,886 children 1–6 years of age, sampled from day-care centres in 62 municipalities all over Sweden, responded to a postal questionnaire regarding symptoms indicating prevalent possible asthma, allergic rhinitis, eczema, and food, furred pet and pollen allergy and other data in their children. Possible asthma was defined as any of the four criteria wheezing four times or more during the last year, physician diagnosis and current wheezing, ever had asthma and current wheezing, and current use of inhalation steroids, all based on questionnaire responses.

Results

The overall prevalence of possible asthma was 8.9%, of eczema 21.7%, of rhinitis 8.1%, and of food allergy 6.6%. There was a highly significant co-occurrence between possible asthma and all atopic manifestations, 35.7% having any of the manifestations. Presence of pet allergy was the manifestation showing the closest co-occurrence with presence of possible asthma, presence of pollen allergy with presence of rhinitis, and presence of food allergy with presence of eczema. Assessed from plots of age-specific prevalence of possible asthma, rhinitis, eczema and food allergy, the prevalence of all manifestations increased from one to three years of age and then decreased, except for rhinitis where the prevalence increased until six years of age, indicating no specific ordered sequence.

Conclusions

Parentally reported possible asthma, eczema and food allergy had a curvilinear prevalence course across age with a maximum at age 3, while rhinitis prevalence increased consistently with age. Co-occurrence between possible asthma and atopic manifestations was common, and some combinations were more common than others, but there was no evidence of a specific ordered onset sequence.

Early eczema and the risk of childhood asthma: a prospective, population-based study

Background

Severe eczema in young children is associated with an increased risk of developing asthma and rhino-conjunctivitis. In the general population, however, most cases of eczema are mild to moderate. In an unselected cohort, we studied the risk of current asthma and the co-existence of allergy-related diseases at 6 years of age among children with and without eczema at 2 years of age.

Methods

Questionnaires assessing various environmental exposures and health variables were administered at 2 years of age. An identical health questionnaire was completed at 6 years of age. The clinical investigation of a random subsample ascertained eczema diagnoses, and missing data were handled by multiple imputation analyses.

Results

The estimate for the association between eczema at 2 years and current asthma at 6 years was OR=1.80 (95% CI 1.10-2.96). Four of ten children with eczema at 6 years had the onset of eczema after the age of 2 years, but the co-existence of different allergy-related diseases at 6 years was higher among those with the onset of eczema before 2 years of age.

Conclusions

Although most cases of eczema in the general population were mild to moderate, early eczema was associated with an increased risk of developing childhood asthma. These findings support the hypothesis of an atopic march in the general population.

Trial registration

The Prevention of Allergy among Children in Trondheim study has been identified as ISRCTN28090297 in the international Current Controlled Trials database

Does eczema in infancy cause hay fever, asthma, or both in childhood? Insights from a novel regression model of sibling data

BACKGROUND

The atopic march hypothesis proposes that eczema precedes the development of asthma and allergic rhinitis.

OBJECTIVE

We sought to assess the evidence for a causal effect of infantile eczema on childhood hay fever, asthma, or both.

METHODS

We used parental reports on infantile eczema and childhood asthma and hay fever for 3778 pairs of 7-year-olds matched to their sibling closest in age within 2 years from the Tasmanian Longitudinal Health Study. We analyzed paired sibling data using a logistic regression model that allowed inference about a causal effect of a familial predictor on a child's outcome by examining the change in association with their cosibling's predictor after adjusting for their own predictor status.

RESULTS

Siblings were concordant for infantile eczema (tetrachoric correlation, 0.40). For having both hay fever and asthma by age 7 years, the association with cosibling's eczema was an odds ratio (OR) of 1.98 (95% CI, 1.37-2.86), which reduced after adjusting for own eczema to an OR of 1.65 (95% CI, 1.17-2.34). For having hay fever only, the association with cosibling's eczema was an OR of 1.68 (95% CI, 1.22-2.31) before and an OR of 1.59 (95% CI, 1.19-2.14) after adjusting for own eczema. There was no association between having asthma only and cosibling's eczema (OR, 1.00; 95% CI, 0.77-1.30).

CONCLUSIONS

Eczema in infancy might have a causal effect on hay fever in children with and perhaps without asthma. The association of infantile eczema on asthma in children without hay fever, which might be early transient wheeze, is unlikely to be causal or familial. These findings have implications for hay fever prevention.

Atopic dermatitis: a candidate for disease-modifying strategy

The concept of disease modification has been introduced to define the therapeutic strategies aimed to break, stop, or reverse the natural course of a chronic invalidating disease. This strategy is tightly related to the biomarker-based stratification of affected patients using genetic and other biological markers. With regard to the progress in understanding the genetic background of atopic dermatitis (AD), its natural history and its pivotal role in the emergence of allergic asthma, the time is mature to foster the research field of biomarkers in AD and to consider the elaboration of disease-modifying strategies in the management of AD with the goal to stop or even reverse the atopic march.

Dissecting the causes of atopic dermatitis in children: less foods, more mites

Atopic dermatitis (AD) is a common, chronic or chronically relapsing, multifactorial skin disease that mainly occurs in children but affects also adults. AD usually begins early in life and often concerns people with a personal or family history of asthma and allergic rhinitis. AD is characterized by eczematous changes in the epidermis and originates from a late, T-cell mediated reaction associated to the formation and production of memory T-cell of TH2 type, occurrence of homing receptor at skin level and cutaneous lymphocyte-associated (CLA) antigens. Extrinsic or allergic AD, but not intrinsic AD, shows high total serum IgE levels and the presence of specific IgE for environmental and food allergens. A pivotal role in the pathogenesis of AD is played by filaggrin, a protein contained in the granular layer of the epidermis regulating the aggregation of keratin filaments. Mutation in the filaggrin gene causes decreased barrier function of the corny layers of the epidermis. This favours the enter through the skin of environmental allergens, especially the house dust mite, that further facilitates such entering by the proteolytic activity of its major allergen Der p 1. In fact, recent advances suggest that the dust mite, more than foods, is the major cause of allergic AD. As far as the causal diagnosis of AD is concerned, there is notable evidence supporting the capacity of the atopy patch test (APT) to reproduce the pathophysiologic events of AD. This makes APT a valuable diagnostic tool for AD.

A long-term follow-up of allergic diseases in Iceland

INTRODUCTION

Allergic disorders are an increasing health problem in many countries, in particular among children. We have evaluated the prevalence and manifestations of allergy in a cohort of young Icelanders for more than two decades. Variations in the epidemiology and clinical expression of allergy in different communities may help to identify etiological factors contributing to these disorders.

METHODS

A cohort of 179 children has been monitored for allergic manifestations for two decades, at the ages of two, four, eight, and 15 years, and most recently at the age of 21 years involving 120 of the participants.

RESULTS

Cumulative prevalences of 40%, 45%, and 29% have been observed, respectively, for rhinoconjunctivitis, eczema, and asthma during the study period. None had developed rhinoconjunctivitis at the age of about 2 years, but the point prevalence gradually increased to 33% at the age of 21 years. Conversely, the prevalence of eczema was 31% at the age of 2 years, but gradually declined to 8% at the age of 21 years. The prevalence of asthma peaked at 28% at the age of 4 years, but declined thereafter and has remained stable at about 13% from the age of eight to 21 years.

DISCUSSION

The prevalence of allergic diseases is high in Iceland among children and young individuals. Asthma and atopic eczema are very common in childhood, but decreases with age while the prevalence of rhinoconjunctivitis increases markedly. The very high and increasing prevalence of rhinoconjunctivitis among 15- to 21-year-old individuals is noteworthy.

Cutting edge: persistence of increased mast cell numbers in tissues links dermatitis to enhanced airway disease in a mouse model of atopy

The development of chronic allergic dermatitis in early life has been associated with increased onset and severity of allergic asthma later in life. However, the mechanisms linking these two diseases are poorly understood. In this study, we report that the development of oxazolone-induced chronic allergic dermatitis, in a mouse model, caused enhanced OVA-induced allergic asthma after the resolution of the former disease. Our findings show that oxazolone-induced dermatitis caused a marked increase in tissue mast cells, which persisted long after the resolution of this disease. Subsequent OVA sensitization and airway challenge of mice that had recovered from dermatitis resulted in increased allergic airway hyperreactivity. The findings demonstrate that the accumulation of mast cells during dermatitis has the detrimental effect of increasing allergic airway hypersensitivity. Importantly, our findings also show that exposure to a given allergen can modify the immune response to an unrelated allergen.

Childhood eczema and rhinitis predict atopic but not nonatopic adult asthma: a prospective cohort study over 4 decades

BACKGROUND

The evidence on whether the atopic march observed in childhood (ie, the progression from eczema to allergic rhinitis and asthma) extends to adulthood is sparse, and there is no evidence on whether the progression leads to a specific phenotype of asthma.

OBJECTIVE

We sought to assess whether childhood eczema and rhinitis are risk factors for specific phenotypes of adult asthma.

METHODS

Participants of the Tasmanian Longitudinal Health Study recruited in 1968 (age range, 6.0-7.0 years) were followed up at age 44 years. The risk of current atopic or nonatopic asthma in middle age characterized by sensitization to aeroallergens given childhood eczema, rhinitis, or both was calculated by using multinomial logistic regression.

RESULTS

No association was found between childhood eczema or rhinitis and nonatopic adult asthma. In contrast, childhood eczema and rhinitis in combination predicted both new-onset atopic asthma by middle age (adjusted multinomial odds ratio [aMOR], 6.3; 95% CI, 1.7-23.2) and the persistence of childhood asthma to adult atopic asthma (aMOR, 11.7; 95% CI, 3.6-37.9). Participants with childhood eczema alone were at increased risk of new-onset atopic asthma (aMOR, 4.1; 95% CI, 1.9-8.8), whereas rhinitis alone predicted the persistence of childhood asthma to atopic asthma (aMOR, 2.7; 95% CI, 1.3-5.6). Of all asthma, 29.7% of persistent atopic asthma and 18.1% of new-onset atopic asthma could be attributed to having childhood eczema and rhinitis.

CONCLUSION

Childhood eczema and rhinitis are strongly associated with the incidence and persistence of adult atopic asthma.

Eczema in early life: genetics, the skin barrier, and lessons learned from birth cohort studies

Eczema is a chronic inflammatory disorder of the skin that affects up to 30% of children. It often afflicts infants in the first few months of life and can be the first indicator of the atopic march. Recent results from birth cohort studies have uncovered novel information regarding genetic and environmental factors that promote the development of eczema. Birth cohort studies provide an optimal study design to elucidate these associations and prospectively track longitudinal data including exposure assessment and health outcomes from birth into early life and childhood. This is especially relevant for eczema given the age specific emergence of this disease. In this review, we will provide a general overview of pediatric eczema and discuss the important findings in the literature with respect to genetics and environmental exposures, highlighting those derived from birth cohort studies. Additionally, we will review how these relate to the atopic march, the hygiene hypothesis and the integrity of the skin barrier.

Relation of early antibiotic use to childhood asthma: confounding by indication?

BACKGROUND

Findings from studies of the relation between early antibiotic use and subsequent asthma have been inconsistent, which may be attributable to methodologic issues.

OBJECTIVE

Our objective was to assess the impact of confounding by indication on the relation of early antibiotic use to childhood asthma through age 5 in a non-selected birth cohort (n=424).

METHODS

Oral antibiotic use was assessed by frequent nurse interviews in the first 9 months of life. Physician-diagnosed active asthma and eczema were assessed by questionnaire at 1, 2, 3, and 5 years, and were considered as ever asthma or ever eczema if positive at any age. Allergen-specific IgE was assessed in plasma at 1, 2, 3, and 5 years. Confounding by indication was investigated by considering the relation of asthma to antibiotic use while controlling for the number of illness visits to a physician in early life.

RESULTS

There was no statistically significant relation of early antibiotic use with physician-diagnosed eczema or allergen-specific IgE. A dose-response relation was evident for antibiotic use with ever asthma (odds ratio [OR]=1.5, P=0.047). Ever asthma also increased significantly with the number of illness visits to a physician (P<0.001). After adjustment for number of illness visits, antibiotic use showed no relation with asthma.

CONCLUSIONS

The relation of asthma to antibiotics in this cohort appears to be an artefact of the strong relation of number of physician visits for illness with both antibiotic use and risk for asthma.

The influence of TSLP on the allergic response

Exposure to allergens first occurs at body surfaces in direct contact with the environment such as the skin, airways, and gastrointestinal tract, and compelling evidence suggests that allergic inflammatory responses are profoundly influenced by the products of epithelial cells located at these sites. One such product is thymic stromal lymphopoietin (TSLP), which is capable of affecting multiple cell lineages involved in allergic reactions. In this review we discuss recent work that has provided insight into the role TSLP plays in both aberrant and protective allergic inflammatory responses, as well as regulation, associations with disease, sources, and functions of this important cytokine.