The excess of atopic eczema in East Germany is related to the intrinsic type

Subtypes of atopic dermatitis: From phenotype to endotype

Atopic dermatitis (AD) is a heterogenous disorder and can be classified into different types. Stratification of subtypes may enable personalized medicine approaches. AD can be categorized into the IgE-high, extrinsic subtype and the IgE-normal, intrinsic subtype. While extrinsic AD is the major subtype possessing skin barrier impairment (high incidence of filaggrin mutations), intrinsic AD occupies about 20% of AD with female dominance and preserved barrier. Extrinsic AD exhibits protein allergy and food allergy, but intrinsic AD shows metal allergy possibly in association with suprabasin deficiency. In particular, accumulated knowledge of food allergy has more clearly characterized extrinsic AD. European American (EA) and Asian AD subtypes have been also proposed. Asian patients with AD are characterized by a unique blended immune dysregulation and barrier feature phenotype between EA patients with AD and those with psoriasis. In another ethnic study, filaggrin loss-of-function mutations are not prevalent in African American patients with AD, and Th1/Th17 attenuation and Th2/Th22 skewing were seen in these patients. Recent endotype classification provides new insights for AD and other allergic disorders. Endotype is defined as the molecular mechanisms underlying the visible features/phenotype. Endotype repertoire harbors activation of type 2 cytokines, type 1 cytokines, and IL-17/IL-22, impairment of epidermal barrier, and abnormalities of intercellular lipids. Classification of endotype has been attempted with serum markers. These lines of evidence indicate a need for personalized or precision medicine appropriate for each subtype of AD.

How does parental history of atopic disease predict the risk of atopic dermatitis in a child? A systematic review and meta-analysis

BACKGROUND

Parental history of atopic disease is a well-established risk factor for the development of atopic dermatitis (AD), but several aspects of this association remain unclear.

OBJECTIVE

We sought to determine the association of parental history of atopic disease with AD in offspring.

METHODS

We searched PubMed and EMBASE through June 2018 for relevant records and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled odds ratios (ORs) with 95% CI were calculated using random-effects models.

RESULTS

A total of 163 records covering 149 unique studies were included. Of these, 119 studies were included in the meta-analysis. Individuals with parental history of atopic disease had increased odds of AD (OR, 1.81; 95% CI, 1.65-1.99). Parental asthma (OR, 1.56; 95% CI, 1.18-2.05) and allergic rhinitis (OR, 1.68; 95% CI, 1.34-2.11) had a smaller effect than AD (OR, 3.30; 95% CI, 2.46-4.42). The effect of maternal and paternal history was comparable for all atopic diseases. An increase in odds was observed when comparing the effect of having 1 (OR, 1.30; 95% CI, 1.15-1.47) or 2 atopic parents (OR, 2.08; 95% CI, 1.83-2.36), as well as having a parent with 1 (OR, 1.49; 95% CI, 1.28-1.74) or more atopic diseases (OR, 2.32; 95% CI, 1.92-2.81).

CONCLUSIONS

This study provides evidence-based risk estimates that may guide physicians who counsel parents with a history of atopic disease about their children's risk of AD. This information is of particular importance for future efforts toward establishing prophylactic interventions for AD on a general population level.

Diagnosis and Management of Atopic Dermatitis: A Review

GENERAL PURPOSE

The purpose of this learning activity is to provide information about the diagnosis and management of atopic dermatitis (AD).

TARGET AUDIENCE

This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and nurses with an interest in skin and wound care.

LEARNING OBJECTIVES/OUTCOMES

After completing this continuing education activity, you should be able to:1. Recall the diagnostic process of AD.2. Identify nonpharmacologic therapies for skin care in patients with AD.3. Explain the pharmacologic management of AD.

ABSTRACT

Atopic dermatitis is a chronic, relapsing, intensely pruritic inflammatory skin disease that affects both children and adults. This article provides an overview of the epidemiology, clinical features, pathophysiology, complications, and specific investigations of atopic dermatitis. The current and novel therapies for the treatment of atopic dermatitis will be discussed.

Comorbidities and the impact of atopic dermatitis

OBJECTIVE

Atopic dermatitis (AD) is a chronic pruritic inflammatory skin disease with substantial patient and population burdens. A number of comorbid health problems occur in patients with AD, aside from the cutaneous signs and symptoms. This review summarizes recent developments in the burden and comorbidities of AD.

DATA SOURCES

Literature review.

STUDY SELECTIONS

Nonsystematic.

RESULTS

Different aspects of AD, such as chronic pruritus, psychosocial distress, and inflammation, can lead to anxiety, depression, or suicidality. Atopic dermatitis is associated with and may predispose to higher risk of other atopic disorders, including asthma, hay fever, food allergy, and eosinophilic esophagitis. Persons with AD appear to be at higher risk for infectious and cardiovascular risk.

CONCLUSION

Atopic dermatitis is associated with substantial burden and comorbidities. Identifying AD comorbidities is essential for proper disease management and improving overall patient outcomes.

The Role of the Environmental Risk Factors in the Pathogenesis and Clinical Outcome of Atopic Dermatitis

Atopic dermatitis (AD) prevalence is rising worldwide. Literature data suggest the incidence of AD in developing countries is gradually getting close to that of developed ones, in which AD affects 20% of the paediatric population. Such an increment, associated with significant variations in prevalence among the various countries, underlines the importance of environmental factors in the disease onset. Among these, great importance is given to hygiene, intestinal microbiota, exposure to bacterial endotoxins, outdoor living with contact to animals, atmospheric pollution, weather, and diet. Genetic (alteration of the skin barrier function) as well as immunologic factors concur with the environmental ones. Only the systematical study of all these elements can best elucidate AD epidemiology.

Incidence Trends of Atopic Dermatitis in Infancy and Early Childhood in a Nationwide Prescription Registry Study in Norway

Importance

With increasing prevalence of atopic dermatitis (AD) and its manifestation in most countries, together with the supporting evidence of the progression to other atopic phenotypes, AD has developed into a worldwide public health concern. The presence of the disease of has increased since the 1950s, but some recent studies suggest a stationary or decreasing trend.

Objective

To analyze a nationwide health register based on prescription data to determine the incidence rate (IR) of AD in an entire pediatric population.

Design, Setting, and Participants

All children resident in Norway younger than 6 years from January 1, 2009, through December 31, 2015, were included in this cohort study. Medical diagnoses and disease-specific medications were used as a proxy for identifying children with AD in this population-based prescription registry study. The prescription study was terminated in 2016. The total number of 295 286 disease-specific prescriptions was analyzed from August 2016 through December 2017. The hypothesis was formulated before, during, and after the data collection.

Main Outcomes and Measures

All children with a medical diagnosis of AD or eczema based on at least 2 prescriptions of topical corticosteroids or at least 1 prescription of topical calcineurin inhibitors. Incidence rates per person-year (PY) and IR ratios were calculated.

Results

A total of 295 286 disease-specific prescriptions were dispensed to 122 470 children, of whom 63 460 had AD and 56 009 (88.3%) had reimbursed prescriptions and associated AD diagnoses. The annual Norwegian study population (aged <6 years) increased from 357 451 children in 2009 to 373 954 in 2015. The overall IR increased from 0.028 per PY (95% CI, 0.028-0.029 per PY) in 2009 to 0.034 per PY (95% CI, 0.033-0.035 per PY) in 2014. For children younger than 1 year, the IR increased from 0.052 per PY (95% CI, 0.050-0.053 PY) in 2009 to 0.073 per PY (95% CI, 0.071-0.075 per PY) in 2014. In this age group, the IR was 53% higher in boys compared with girls (IR ratio, 1.53; 95% CI, 1.49-1.57; P < .001). The incidence proportion before the age of 6 years was 17.4% (95% CI, 17.2%-17.7%). The primary seasons for the onset of AD were winter and spring.

Conclusions and Relevance

This nationwide study suggests an increase in the IR of pediatric AD, especially among children younger than 1 year. This study's findings suggest that increase occurred with a higher IR during winter and spring seasons. Atopic dermatitis had an earlier onset in boys than in girls. During the study period, more than 1 in 6 children younger than 6 years had, at some point, been affected by AD.

Introduction

Atopic dermatitis (AD) is a chronic relapsing condition that is characterized by itching and redness of the skin. Our modern usage of atopic dermatitis dates back to 1933, when Wise and Sulzberger first coined the term to signify the disease's close association with other respiratory atopy, such as bronchial asthma and allergic rhinitis. A recent systematic review of 69 cross-sectional and cohort studies has confirmed that AD is now a worldwide phenomenon with lifetime AD prevalences of well over 20% in many affluent country settings. Although there is no obvious consistent overall global trend in the prevalence of AD, studies have shown that climate, urbanization, lifestyle, and socioeconomic class influence the prevalence of atopic dermatitis. Despite the pervasiveness of the disease, an understanding of atopic dermatitis has been hampered by a number of factors. Data suggests that extrinsic environmental factors work in concert with intrinsic immune mechanism and genetic factors to drive disease progression. With such a complex etiology, management of atopic dermatitis currently at best achieves symptomatic control rather than cure. This approach poses a significant burden on healthcare resources, as well as patients' quality of life. Current management methods of AD often involves a combination of non-pharmacologic modalities and prescription medications. Though they can be effective when employed, there are significant barriers to treatment for patients including time, costs, and medication side effects. Our aim, throughout this text, is to explore the complexities of AD, providing the healthcare provider with tips and tricks to improve patient care and satisfaction and the most current trends and treatment approaches on the horizon.

Humoral and Cellular Autoreactivity to Epidermal Proteins in Atopic Dermatitis

Atopic dermatitis (AD), a chronic relapsing inflammatory disease of the skin, is an important public health concern affecting 10-20 % of children worldwide. The etiology and pathogenesis of AD involve the interplay of genetic and environmental factors, including abnormalities in skin integrity and a skewed immune system usually driven by a Th2 phenotype in childhood with a switch to Th1 in the chronic phase of disease. Children and adults with AD commonly have elevated IgE levels directed to multiple different antigens, including aeroallergens, food allergens, and microbial proteins. IgE targeting self-antigens from epidermal proteins have been detected in up to 91 % of patients, particularly in severe persistent AD. It has been suggested that the occurrence of autoreactivity develops in early childhood. However, it is not clear yet if autoreactive IgEs in patients with AD are pathogenic or just an epiphenomenon. The fact that these autoantibodies are associated with severity and are not present in other allergic or skin diseases favors the pathogenicity of IgE-mediated autoreactivity in AD. In this review, we evaluate the pathogenesis of AD and the emerging role of autoreactivity to various keratinocyte antigens involving both the humoral and cellular components of the immune system.

What can reunification of East and West Germany tell us about the cause of the allergy epidemic?

The increase of allergies in East Germany--reaching West German prevalence shortly after the reunification--is considered a model for the allergy epidemic in the western world. Whether such a pattern was observed in all comparison studies and for all allergic manifestations is not known because a complete overview is missing. Hints about possible causal factors for the allergy epidemic could be gained by identifying known risk factors, which explain the observed pattern of allergy development in Germany. Again, an overview about these efforts is missing. We identified 14 cross-sectional studies conducted after 1989 and calculated prevalence ratios (West/East) for asthma, hayfever, eczema and allergic sensitization. Additionally, a tabular overview about the explanatory power of risk factors hypothesized in the nineties and covering outdoor exposure, indoor factors, early childhood influences, nutrition as well as awareness is given. At the time of the German reunification, the prevalence ratio West/East was largest for hayfever and sensitization to birch pollen, less pronounced for the other phenotypes and even less than one for atopic eczema. Hayfever and sensitization to birch pollen also showed the steepest increase in East Germany afterwards. Single-room heating with fossil fuels and living as only child in a family were identified as explaining up to 23.5% of the excess trend in East compared to the trend in West. Hayfever as most typical atopic disease showed the difference in allergy pattern between East and West Germany clearest. Risk factors identified for these phenotypes are completely different (single child) or even act in the opposite direction (single-room heating) from classical risk factors for airway diseases. This might be the most important lesson from the West/East German experience. It already stimulated many other studies focussing on protective factors such as microbial stimulation.

Epidemiology of Frequently Occurring Skin Diseases in Italian Children from 2006 to 2012: A Retrospective, Population-Based Study

BACKGROUND

Recent estimates indicate an increase in the prevalence of skin diseases in children. Few large epidemiologic studies have examined prevalence trends in Europe. This study evaluated the incidence and prevalence of frequently occurring pediatric skin diseases (PSDs) in Italy as seen by family pediatricians (FPs).

METHODS

Data were retrospectively extracted from the Pedianet database (2006-2012) in children ages 0 to 14 years presenting with a skin disease at their FP. The incidence and prevalence estimates were calculated per year and stratified according to sex, age, and geographic area.

RESULTS

A mean of 145,233 children (52.1% male) across five Italian regions were registered with their participating FP for a total of 913,253 person-years of follow-up. The majority of patients were from the northeast (44.6%) and 37.7% were ages 5-9 years. Incidence estimates (new cases/1,000 person-years) for most PSDs increased from 2006 to 2012, the highest being for atopic dermatitis (AD) (14.1 vs 16.5), acute urticaria (10.1 vs 11.6), and contact dermatitis (9.3 vs 10.8), whereas psoriasis remained unchanged over the 7 years (0.61 vs 0.57). In contrast, prevalence estimates (cases/100 patients) increased two to three times for several PSDs, including AD (2.7% vs 8.5%), seborrheic dermatitis (0.5% vs 1.6%), chronic urticaria (0.4% vs 0.8%), and psoriasis (0.09% vs 0.22%). Differences in prevalence according to age range and geographic area were observed for psoriasis, AD, and urticaria.

CONCLUSION

This study provides comprehensive evidence of the increasing prevalence and incidence of PSDs across Italy. Additional causality studies to address this important clinical and psychosocial problem are recommended.

Factors associated with atopy in toddlers: a case-control study

In this case-control study the association between the approaches used to feed infants, together with known family and environmental factors, and the occurrence of atopic illness in toddlers between the ages of 4 months to 3 years in Hong Kong was examined. A total of 206 subjects were recruited from April to June of 2014. The results obtained by binary logistic regression indicated that atopy is associated with boys (OR 2.072, CI 1.089-3.941), the maternal use of antibiotics in utero or while breast feeding (OR 2.276, CI 1.151-4.504), the later commencement of mixed feeding (OR 2.497, CI 1.025-6.082), breast feeding exclusively for 3 months (OR 1.972, CI 1.009-3.857), and having a mother who was diagnosed with eczema (OR 4.510, CI 1.764-11.530). Although an exclusive reliance on breast feeding has been shown to be predictive of atopy among toddlers, the positive qualities of breast milk cannot be ignored. A further study of the contents and nutritional values of breast milk is warranted.

New insights into the epidemiology of childhood atopic dermatitis

There is a growing desire to explain the worldwide rise in the prevalence of atopic dermatitis (AD). Trend data on the burden of AD suggest that the picture in the developing world may soon resemble that of wealthier nations, where AD affects over 20% of children. This, combined with significant variations in prevalence within countries, emphasizes the importance of environmental factors. Many hypotheses have been explored, from the modulation of immune priming by hygiene, gut microbiota diversity, and exposure to endotoxins through farm animals to the effects of pollution, climate, and diet. The discovery of the filaggrin skin barrier gene and its importance in AD development and severity has brought the focus on gene-environment interactions and the identification of environmental factors that impact on skin barrier function. This article reviews our current understanding of the epidemiology of AD, with an emphasis on the findings reported in the international literature over the last 5 years.

Investigating international time trends in the incidence and prevalence of atopic eczema 1990-2010: a systematic review of epidemiological studies

The prevalence of atopic eczema has been found to have increased greatly in some parts of the world. Building on a systematic review of global disease trends in asthma, our objective was to study trends in incidence and prevalence of atopic eczema. Disease trends are important for health service planning and for generating hypotheses regarding the aetiology of chronic disorders. We conducted a systematic search for high quality reports of cohort, repeated cross-sectional and routine healthcare database-based studies in seven electronic databases. Studies were required to report on at least two measures of the incidence and/or prevalence of atopic eczema between 1990 and 2010 and needed to use comparable methods at all assessment points. We retrieved 2,464 citations, from which we included 69 reports. Assessing global trends was complicated by the use of a range of outcome measures across studies and possible changes in diagnostic criteria over time. Notwithstanding these difficulties, there was evidence suggesting that the prevalence of atopic eczema was increasing in Africa, eastern Asia, western Europe and parts of northern Europe (i.e. the UK). No clear trends were identified in other regions. There was inadequate study coverage worldwide, particularly for repeated measures of atopic eczema incidence. Further epidemiological work is needed to investigate trends in what is now one of the most common long-term disorders globally. A range of relevant measures of incidence and prevalence, careful use of definitions and description of diagnostic criteria, improved study design, more comprehensive reporting and appropriate interpretation of these data are all essential to ensure that this important field of epidemiological enquiry progresses in a scientifically robust manner.

A group of atopic dermatitis without IgE elevation or barrier impairment shows a high Th1 frequency: possible immunological state of the intrinsic type

BACKGROUND

Atopic dermatitis (AD) can be classified into the major extrinsic type with high serum IgE levels and impaired barrier, and the minor intrinsic type with normal IgE levels and unimpaired barrier.

OBJECTIVE

To characterize the intrinsic type of Japanese AD patients in the T helper cell polarization in relation to the barrier condition.

METHODS

Enrolled in this study were 21 AD patients with IgE<200kU/L (IgE-low group; 82.5±59.6kU/L) having unimpaired barrier, and 48 AD patients with IgE>500kU/L (IgE-high group; 8.050±10.400kU/L). We investigated filaggrin gene (FLG) mutations evaluated in the eight loci common to Japanese patients, circulating Th1, Th2 and Th17 cells by intracellular cytokine staining and flow cytometry, and blood levels of CCL17/TARC, IL-18, and substance P by ELISA.

RESULTS

The incidence of FLG mutations was significantly lower in the IgE-low group (10.5%) than the IgE-high group (44.4%) (normal individuals, 3.7%). The percentage of IFN-γ-producing Th1, but not Th2 or Th17, was significantly higher in the IgE-low than IgE-high group. Accordingly, Th2-attracting chemokine CCL17/TARC, was significantly lower in the IgE-low than the IgE-high group. There were no differences between them in serum IL-18 levels, or the plasma substance P levels or its correlation with pruritus.

CONCLUSION

The IgE-low group differed from the IgE-high group in that it had much less FLG mutations, increased frequency of Th1 cells, and lower levels of CCL17. In the intrinsic type, non-protein antigens capable of penetrating the unimpaired barrier may induce a Th1 eczematous response.

The prevalence of atopic dermatitis in children is influenced by their parents' education: results of two cross-sectional studies conducted in Upper Austria

Atopic dermatitis (AD) is an important health problem worldwide. Several studies have shown that a positive family history is a strong risk factor. We studied the prevalence of AD among 23,583 Austrian school children and examined the association between the prevalence of AD in children and their parents' education at two points in time. As part of the International Study of Asthma and Allergy in Childhood programme, two cross-sectional studies were conducted in Upper Austria (Federal State of Austria) between the years 1995-97 (Phase I) and 2001-03 (Phase III). All pupils of pre-school classes and of first and second grade of all elementary schools in seven districts of Upper Austria received standardized questionnaires, resulting in a total of 13,399 (Phase I) and 13,731 (Phase III) children. All variables examined concerning AD showed an increase in prevalence in the age group examined: During the first study, 9.6% of the children ever had eczema diagnosed by a doctor (Phase III: 13.3%), whereas 9.2% ever had symptoms of AD (Phase III: 11.0%). In Phase I, 6.0% of the children had an itchy rash in the past 12 months (Phase III: 6.7%). In both studies, high parental education (i.e. high school or university degree) was an independent statistically significant risk factor for eczema in the child, resulting in an adjusted Odds Ratio between 1.13 and 1.37. In a census-like-survey, we are able to demonstrate a statistically significant association between parental education and the prevalence of AD in their children, which is independent of a possible parental AD.

Differences in allergy trends between East and West Germany and possible explanations

BACKGROUND

At the time of the German reunification in 1990, manifestations of most allergic diseases were less prevalent in East than in West Germany. It was hypothesized that these East-West differences would diminish with lifestyle and pollution changes in East Germany.

OBJECTIVE

To investigate whether changes in the prevalence of asthma, hayfever, eczema or allergic sensitization in East Germany approached the levels seen in West Germany and to identify possible lifestyle or environmental factors that may influence this.

METHODS

Between 1991 and 2000, 6-year-old children from four areas in East Germany participated in an annual survey. Every 3rd year, a parallel survey was performed in four areas of West Germany. In total, 31 903 children were included. Parents completed a questionnaire regarding lifestyle factors and diagnoses and symptoms of asthma, hayfever and eczema. In sub-areas, eczema was clinically assessed by a dermatologist. Specific IgE sensitization was determined for 6121 children. Logistic regression was used to analyse differences in time trends and the influence of lifestyle and pollution changes.

RESULTS

Lifestyle and pollution changed significantly differently between East and West Germany. The trends in hayfever and in strong (specific IgE >3.5) sensitization against pollen, and particularly birch pollen, were steeper in East than in West Germany. The trend towards marked pollen sensitization was four times stronger (95% confidence interval 1.2-13.9) in East than in West Germany. Increasing numbers of only children, less single-room heating with fossil fuels and increasing importance of traffic-related pollution in East Germany partly explained these differences in time trends.

CONCLUSIONS

Hayfever and sensitization against pollen were the most sensitive allergic manifestations to changes experienced specifically in East Germany. Influences of lifestyle (single-room heating, living as a single child) were important in explaining different trend developments.

Extrinsic and intrinsic types of atopic dermatitis

Atopic dermatitis (AD) can be categorized into the extrinsic and intrinsic types. Extrinsic or allergic AD shows high total serum IgE levels and the presence of specific IgE for environmental and food allergens, whereas intrinsic or non-allergic AD exhibits normal total IgE values and the absence of specific IgE. While extrinsic AD is the classical type with high prevalence, the incidence of intrinsic AD is approximately 20% with female predominance. The clinical features of intrinsic AD include relative late onset, milder severity, and Dennie-Morgan folds, but no ichthyosis vulgris or palmar hyperlinearity. The skin barrier is perturbed in the extrinsic, but not intrinsic type. Filaggrin gene mutations are not a feature of intrinsic AD. The intrinsic type is immunologically characterized by the lower expression of interleukin (IL) -4, IL-5, and IL-13, and the higher expression of interferon-gamma. It is suggested that intrinsic AD patients are not sensitized with protein allergens, which induce Th2 responses, but with other antigens, and metals might be one of the candidates of such antigens.

The association of allergic symptoms with sensitization to inhalant allergens in childhood

Although it is generally agreed that sensitization is an important risk factor for allergic diseases, the extent to which sensitization accounts for allergic symptoms in children is controversial. As part of the Aalst Allergy Study, this cross-sectional study investigated the prevalence of allergic symptoms and their association with sensitization in an unselected population of Flemish children aged 3.4-14.8 yr. Skin prick testing with the most common aeroallergens was performed and allergic symptoms were documented by a parental questionnaire. In the children older than 6 yr, a significant association of current wheezing, current dyspnea, airway hyperreactivity, rhinoconjunctivitis, and current eczema with sensitization was found, while in the pre-school children these associations were less pronounced. The association with sensitization was strongest for rhinoconjunctivitis and current respiratory symptoms - the association was less striking for children with current eczema. The impact of a positive family history of allergy on the association with sensitization was more important for eczema than for the other analyzed allergic symptoms. Persistent and late-onset wheezers were significantly more likely than non-wheezers and transient early wheezers to be associated with sensitization and a personal history of rhinoconjunctivitis. Late-onset wheezing was associated with a positive family history of allergy, while transient early wheezing was associated with day-care attendance. An association with eczema was found for all three childhood wheezing phenotypes. The association of allergic symptoms with sensitization is significant in the older but less pronounced in pre-school children and is more pronounced for current allergic symptoms. Diagnosis and disease definition of allergy symptoms remains difficult at pre-school age. The influence of a positive family history of allergy on the association of the respective allergic symptoms with sensitization was most important for eczema. Our data confirm the atopic characteristics of the different wheeze phenotypes.

The prevalence of allergic diseases in an unselected group of 6-year-old children. The DARC birth cohort study

This study determines the prevalence of atopic dermatitis, asthma, rhinoconjunctivitis, food hypersensitivity and urticaria and the frequency of sensitization in children with and without clinical allergic disease. In an ongoing prospective non-interventional birth cohort study of 562 unselected children, 404 children were subjected to interview, clinical examination, lung function measurements and allergy testing at 6 yr of age. Sensitization measured by skin prick test (SPT) and specific immunoglobulin E (S-IgE) was determined for 24 different allergens. The 1-yr period prevalence of atopic dermatitis, asthma and rhinoconjunctivitis was 14.4%, 6.2% and 13.6%. 25.7% of the children suffered from at least one of the three diseases. The frequency of sensitization in children with no disease (controls), any allergic disease, atopic dermatitis, asthma and rhinoconjunctivitis was 17%, 45%, 47%, 56% and 55% (defined as SPT >or=3 mm and/or S-IgE >or=0.35 kU/l for at least one allergen). Symptoms were linked to sensitization for 44% in the asthma group and 42% in the rhinoconjunctivitis group, whereas sensitization could not be linked to worsening of the eczema in any cases of atopic dermatitis. Overlap between the three diseases was significantly more frequent in sensitized children than in non-sensitized (19/46 = 41% vs. 9/58 = 16%, p = 0.004). The prevalence of food hypersensitivity and urticaria was 1.2% and 5.4% respectively. In unselected 6 yr old children, approximately half of the children with atopic dermatitis, asthma or rhinoconjunctivitis are IgE-sensitized. Sensitization tends to link these diseases to each other.

The impact of allergy on atopic eczema from data from epidemiological studies

PURPOSE OF REVIEW

We aimed to review the association between atopic eczema and allergic sensitization and food allergy and its determinants on the basis of current epidemiological literature.

RECENT FINDINGS

About 50% of children with atopic eczema and about 35% of adults are sensitized to common allergens. Gender, geography (e.g. East and West Germany), and socioeconomic factors determine the proportion of atopic eczema with allergic sensitization. Allergic sensitization in addition to atopic eczema obviously increases the risk for respiratory allergies. Sensitization to house dust mites seems to be important and clinically relevant for atopic eczema. Population-based studies on the association between food allergy and atopic eczema are limited. Although, up to 40% of children in hospital settings react to certain food allergens by a flare-up of their atopic eczema, there is an indication that on a population basis, adults with atopic eczema do only react occasionally with a worsening of their skin disease due to food allergens.

SUMMARY

Atopic eczema is not necessarily associated with allergic sensitization. Sensitization to house dust mites, however, seems to be clinically relevant. The impact of food allergy on atopic eczema is difficult to assess on the basis of epidemiological studies and more detailed studies are needed.

Gender differences in skin: a review of the literature

BACKGROUND

There has been increasing interest in studying gender differences in skin to learn more about disease pathogenesis and to discover more effective treatments. Recent advances have been made in our understanding of these differences in skin histology, physiology, and immunology, and they have implications for diseases such as acne, eczema, alopecia, skin cancer, wound healing, and rheumatologic diseases with skin manifestations.

OBJECTIVE

This article reviews advances in our understanding of gender differences in skin.

METHODS

Using the PubMed database, broad searches for topics, with search terms such as gender differences in skin and sex differences in skin, as well as targeted searches for gender differences in specific dermatologic diseases, such as gender differences in melanoma, were performed. Additional articles were identified from cited references. Articles reporting gender differences in the following areas were reviewed: acne, skin cancer, wound healing, immunology, hair/alopecia, histology and skin physiology, disease-specific gender differences, and psychological responses to disease burden.

RESULTS

A recurring theme encountered in many of the articles reviewed referred to a delicate balance between normal and pathogenic conditions. This theme is highlighted by the complex interplay between estrogens and androgens in men and women, and how changes and adaptations with aging affect the disease process. Sex steroids modulate epidermal and dermal thickness as well as immune system function, and changes in these hormonal levels with aging and/or disease processes alter skin surface pH, quality of wound healing, and propensity to develop autoimmune disease, thereby significantly influencing potential for infection and other disease states. Gender differences in alopecia, acne, and skin cancers also distinguish hormonal interactions as a major target for which more research is needed to translate current findings to clinically significant diagnostic and therapeutic applications.

CONCLUSIONS

The published findings on gender differences in skin yielded many advances in our understanding of cancer, immunology, psychology, skin histology, and specific dermatologic diseases. These advances will enable us to learn more about disease pathogenesis, with the goal of offering better treatments. Although gender differences can help us to individually tailor clinical management of disease processes, it is important to remember that a patient's sex should not radically alter diagnostic or therapeutic efforts until clinically significant differences between males and females arise from these findings. Because many of the results reviewed did not originate from randomized controlled clinical trials, it is difficult to generalize the data to the general population. However, the pressing need for additional research in these areas becomes exceedingly clear, and there is already a strong foundation on which to base future investigations.

Immunology and treatment of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory disease hypothesized to be the product of complex interactions among the host's environment, susceptibility genes, skin barrier dysfunction, and immune system dysregulation. The objective of this article is to describe the pathobiology and treatment of AD, with particular focus on the role of immune system dysregulation and therapies designed to target this. Literature review indicates that there are immunologic differences between the lesional and non-lesional skin of atopic individuals, and that the non-lesional skin of atopic individuals presents an immunologic profile distinct from that of the skin of healthy individuals. Thus, immune system dysregulation is postulated to be a key contributing factor to the complex etiology of AD. Immunomodulatory agents such as topical corticosteroids (TCSs) and topical calcineurin inhibitors (TCIs), which address the underlying immunopathology of AD, are the foundation for the pharmacologic treatment of flares. TCSs and TCIs both target the inflammatory response responsible for an AD flare but via two distinct mechanisms of action. Whereas TCSs have a more widespread impact on the immune system, the action of TCIs is targeted to the calcineurin pathway and inhibition of T-cell activation. Together, TCSs and TCIs represent the backbone of a long-term treatment strategy for AD.

Pulsed-field gel electrophoresis of Staphylococcus aureus isolates from atopic patients revealing presence of similar strains in isolates from children and their parents

Skin colonization with Staphylococcus aureus is often associated with atopic dermatitis, and staphylococcal enterotoxins have been implicated in the etiology of atopic disease. In this study, the colonization of patients with atopic dermatitis and their parents was investigated in order to evaluate the possibility of intrafamiliar transmission. S. aureus strains were isolated from 30 of 45 patients (66%). In 19 of 29 families (65%), at least one parent carried S. aureus, and the overall colonization rate of the parents was 48%. All strains were typed by pulsed-field gel electrophoresis (PFGE), and the presence of enterotoxin genes in the strains was assayed by multiplex PCR. A high percentage (84%) of the isolates present on the children and on at least one of their parents displayed identical PFGE and enterotoxin patterns as well as identical antibiotic resistance profiles, indicating intrafamiliar transmission. Forty-five percent of the strains did not carry any enterotoxin gene. The most frequently found enterotoxin genes were seg and sei, which were present in 36% of the strains, and seb, which was found in 24% of the strains. The other toxin genes occurred only in low frequencies. Most strains were resistant to penicillin (82%), and 15% showed resistance to more than one antibiotic. Intermediately-vancomycin-resistant S. aureus or methicillin-resistant S. aureus strains were not detected. In conclusion, this study indicates that the colonization rate of parents of atopic children is rather high and may increase the risk of recolonization of the child.

The role of atopic sensitization in flexural eczema: findings from the International Study of Asthma and Allergies in Childhood Phase Two

BACKGROUND

The association between allergic sensitization and eczema has been debated for years.

OBJECTIVE

We sought to determine and compare the strength of the association between allergen skin sensitization and eczema in both developing and industrialized countries.

METHODS

Twenty-eight thousand five hundred ninety-one randomly selected 8- to 12-year-old schoolchildren in 20 countries were physically examined for flexural eczema and received skin prick testing to Dermatophagoides pteronyssinus, Dermatophagoides farinae, cat hair, Alternaria tenuis, mixed tree and grass pollen, and allergens of local relevance.

RESULTS

The age- and sex-adjusted odds ratios (ORs) for a positive association between flexural eczema and atopy ranged between 0.74 (95% CI, 0.31-1.81) and 4.53 (95% CI, 1.72-11.93), with a significantly stronger association in affluent compared with nonaffluent countries (combined age- and sex-adjusted OR(affluent) = 2.69 [95% CI, 2.31-3.13] and OR(nonaffluent) = 1.17 [95% CI, 0.81-1.70]). The combined population attributable fraction for atopy in flexural eczema was 27.9% for affluent and 1.2% for nonaffluent-country centers. Correlating gross national per-capita income with either ORs or population attributable fractions for atopy in flexural eczema confirmed a highly significant positive association (P = .006 and P < .001, respectively).

CONCLUSIONS

The association between atopy and flexural eczema is weak and more variable than previously suggested, and the strength of this association is positively linked to gross national income.

[Allergic diseases. Results from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS)]

In the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) from 2003-2006 information was collected on allergic diseases (asthma, atopic dermatitis, hay fever, allergic contact eczema) from a population-based sample of 17,641 0-to 17-year-olds, and blood samples were studied for specific IgE antibodies to 20 common allergens. The lifetime prevalence (LTP) of at least one atopic disease was 22.9 % (95 % CI: 22.0-23.7 %), the 12-month prevalence (12MP) was 16.1 % (15.4-16.8 %); boys (17.3; 16.3-18.2 %) were more frequently affected than girls (14.9; 14.0-15.8 %). Children with a background of migration were less often currently affected by an atopic disease, as were children from families of low social status. According to parents' accounts, the LTP of allergic contact eczema was 9.9 % (9.4-10.5 %); girls (13.8;12.9-14.8) were more frequently affected than boys (6.2; 5.6-6.9 %). Of the 3- to 17-year-olds, 40.8 % (39.6-42.0 %) were sensitised to at least one of the allergens tested; boys (45.0; 43.5-46.5 %) more frequently so than girls (36.4; 35.0-37.9 %). In the states of the former FRG, the LTP of allergic contact eczema was higher (10.2; 9.6-10.9 %) than those in the former GDR (8.4 % 7.4-9.6 %); otherwise there were no East-West differences. The KiGGS data provide the first nationally representative data on allergic diseases and sensitisation. The differences in prevalence observed correspond to a great extent with previous studies and may support the hygiene hypothesis. The prevalences in East and West Germany now seem to have equalised.

The relevance of microbial allergens to the IgE antibody repertoire in atopic and nonatopic eczema

BACKGROUND

A propensity to microbial skin infections has been reported in atopic ("high IgE") and nonatopic ("low IgE") forms of eczema. However, the relationship between antimicrobial IgE antibodies and nonatopic disease is unclear.

OBJECTIVE

We examined the relevance of microbial allergens to the allergen-specific IgE antibody repertoire in patients with atopic dermatitis.

METHODS

Patients with IgE levels of less than 150 IU/mL were stratified according to sensitivity (n = 22) or no sensitivity (n = 27) to 11 common food allergens and aeroallergens. The prevalence and titers of antimicrobial IgE antibodies were compared with those of patients (n = 36) with increased total IgE levels (>150 IU/mL). Skin-derived serum chemokines were also analyzed.

RESULTS

Patients with low IgE levels showed decreased disease severity, increased age of onset, a striking female predominance, and a distinct distribution of skin lesions. High titer IgE antibodies (sum of 8 bacterial and fungal allergens = 29.8 +/- 32.6 IU/mL) and multisensitization specific for microbial allergens was characteristic of patients with high IgE levels, with an overall 84% positivity; however, antimicrobial IgE antibodies comprised 3% or less of allergen-specific IgE antibodies. By contrast, antimicrobial IgE antibodies were detected in only 20% of patients with low IgE, and titers were negligible, irrespective of sensitization to common allergens. These patients were monosensitized, and exclusive microbial sensitivity was uncommon (10%). Patients with low IgE with no sensitivity to common allergens had lower levels of serum macrophage inflammatory protein 3alpha compared with their sensitized counterparts.

CONCLUSION

Antimicrobial IgE antibodies are uncommon in patients with atopic dermatitis with low IgE levels.

CLINICAL IMPLICATIONS

Hypersensitivity to microbial allergens is an unlikely trigger for eczematous eruptions in patients with low IgE levels.

Preschool children's health and its association with parental education and individual living conditions in East and West Germany

Background

Social inequalities in health exist globally and are a major public health concern. This study focus on a systematic investigation into the associations between health indicators, living conditions and parental educational level as indicator of the social status of 6-year-old children living in West and East Germany in the decade after re-unification. Explanations of observed associations between parental education and health indicators were examined.

Methods

All boys and girls entering elementary school and living in predefined areas of East and West Germany were invited to participate in a series of cross-sectional surveys conducted between 1991 and 2000. Data of 28,888 German children with information on parental education were included in the analysis. Information about educational level of the parents, individual living conditions, symptoms and diagnoses of infectious diseases and allergies were taken from questionnaire. At the day of investigation, atopic eczema was diagnosed by dermatologists, blood was taken for the determination of allergen-specific immuno-globulin E, height and weight was measured and lung function tests were done in subgroups. Regression analysis was applied to investigate the associations between the health indicators and parental educational level as well as the child's living conditions. Gender, urban/rural residency and year of survey were used to control for confounding.

Results

Average response was 83% in East Germany and 71% in West Germany. Strong associations between health indicators and parental education were observed. Higher educated parents reported more diagnoses and symptoms than less educated. Children of higher educated parents were also more often sensitized against grass pollen or house dust mites, but had higher birth weights, lower airway resistance and were less overweight at the age of six. Furthermore, most of the health indicators were significantly associated with one or more living conditions such as living as a single child, unfavourable indoor air, damp housing condition, maternal smoking during pregnancy or living near a busy road. The total lung capacity and the prevalence of an atopic eczema at the day of investigation were the only health indicators those did not show associations with any of the predictor variables.

Conclusion

Despite large differences in living conditions and evidence that some poor health outcomes were directly associated with poor living conditions, only few indicators demonstrated poorer health in social disadvantaged children. These were in both parts of Germany increased levels of overweight, higher airway resistance and, in East Germany only, reduced height in children with lower educated parents compared to those of higher education. In both East and West Germany, higher prevalence of airway symptoms was associated with a damp housing condition, and lower birth weight, reduced height and increased airway resistance at the age of six were associated with maternal smoking during pregnancy. The latter explained to a large extent the difference in birth weight and airway resistance between the educational groups.

The course of eczema in children aged 5-7 years and its relation to atopy: differences between boys and girls

BACKGROUND

The role of atopy in the pathophysiology of eczema is still under debate. The concept and analyses of the nonatopic and atopic subtypes of eczema have gained increasing interest in recent studies. The course of these subtypes and differences between boys and girls have not been investigated so far.

OBJECTIVES

To examine the course of nonatopic and atopic eczema in preschool children from Germany with regard to sex.

METHODS

Repeated cross-sectional studies were performed in 5-7-year-old preschool children from Germany between 1994 and 2000. Individuals with eczema were identified by a dermatological examination. In addition to a questionnaire, skin prick tests and analyses of serum IgE antibodies against seven and five environmental allergens, respectively, were performed. Atopy was defined by sensitization to at least one of five common aeroallergens (birch, grass and mugwort pollen, house dust mites, cat dander). In part of the study population investigations of spare time behaviour and skin function were carried out (including stratum corneum hydration and skin surface pH).

RESULTS

A total of 2693 girls and 2783 boys underwent a full dermatological examination of the skin and determination of sensitization. Among the girls, 8.7% demonstrated eczema clinically at the day of investigation in contrast to 6.1% of the boys. In girls, early onset eczema (< 2 years of age) was strongly related to atopy at age 5-7 years [odds ratio (OR) 3.7; 95% confidence interval (CI) 2.7-5.1], whereas late-onset eczema (> or = 2 years of age) was not (OR 1.0; 95% CI 0.7-1.5). Boys were more often atopic at the age of 5-7 years than girls (28.3% vs. 20.6%), and early and late-onset eczema were related to atopy without such a difference (OR 2.8, 95% CI 2.0-4.0; OR 1.9, 95% CI 1.3-2.8, respectively). The excess of current eczema in 5-7-year-old girls compared with boys was related to the nonatopic type. The higher susceptibility of girls in that age group to develop eczema was reflected by the skin physiological examination: even girls without eczema had significantly higher skin surface pH and lower stratum corneum hydration than boys. Additionally, questionnaire data revealed that girls more often than boys predominantly played indoors, which was associated with more eczema.

CONCLUSIONS

Atopy and eczema develop differently in boys and girls. Boys are more often atopic, whereas girls suffer significantly more often from eczema without relation to atopy. The nonatopic type of eczema in preschool girls is noticed predominantly after their second birthday. Genetic and lifestyle factors may contribute to this difference.

Atopische Dermatitis: Hygiene-Hypothese

The prevalence of atopic diseases has steadily increased over the past decades. While genetic predisposition remains an important risk factor, environmental conditions appear to be additional relevant trigger factors, leading to the development of the "hygiene hypothesis". Current data indicates that atopic respiratory diseases seem to occur less frequently following helminth infections. This effect may be due to the induction of anti-inflammatory cytokines during the helminth infection. In contrast, atopic dermatitis seems to represent a separate entity influenced by more than "allergic sensitization". Recent data demonstrate a reduced risk for the development of atopic dermatitis following helminth infections. Further studies are needed to more closely examine the connections between helminth infections and this chronic skin disease, as well as to identify immunologic pathways.

Low prevalence of the intrinsic form of atopic dermatitis among adult patients

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease commonly associated with respiratory allergies such as rhinitis and asthma, and a high serum level of IgE. In contrast to the 'classic' IgE-mediated allergic (extrinsic) form of AD, approximately 20% of the patients are reported to show normal IgE levels, lack of sensitizations towards environmental allergens, and absence of associated respiratory allergies. Accordingly, these patients are assigned to a nonallergic (intrinsic) form of the disease.

OBJECTIVES

In order to define these two forms of AD more closely, 259 adult patients with AD were investigated.

RESULTS

After a thorough diagnostic workup there were 18 patients (6.9%), who fulfilled the criteria of intrinsic AD. After follow-up, four additional patients had developed respiratory allergies or IgE-mediated sensitizations resulting in an overall proportion for intrinsic AD of 5.4%.

CONCLUSIONS

Based on these figures the nature and relevance of the intrinsic form of AD deserves further evaluation.

Comparison of fecal microflora in children with atopic eczema/dermatitis syndrome according to IgE sensitization to food

Atopic eczema/dermatitis syndrome (AEDS) commonly often arises during early infancy. In several intervention studies a beneficial influence on AEDS course of certain intestinal bacteria, administered as 'probiotics', has been described. To evaluate the possible role of the natural intestinal microflora in children with allergic eczema/dermatitis syndrome regarding immediate type hypersensitivity to food allergens, children with food allergy (AAEDS, n = 68) have been compared with children without detectable food allergy (NAEDS, n = 25). All children (n = 93) in preschool age, mean age of 2.6 (+/-1.8) years, diagnosed with AEDS who were treated as inpatients in 2003 in a dermatological hospital were included. The correlation between fecal microflora, parasites and specific immunoglobulin E (IgE) antibodies against common food allergens was analyzed. A similar composition of intestinal microflora in children with AAEDS and NAAEDS was found. The food allergens that were most frequently detected were egg white, cow milk, casein, peanut and hazelnut. Furthermore, a significant association between IgE sensitization against important food allergens and components of the fecal microflora could not be demonstrated. With aging changes occur in the intestinal microbiota [Proteus/Klebsiella and age (rho = -0.607) and Enterococcus and age (rho = -0.428)]. In two subjects of the AAEDS group Blastocystis hominis was found. The composition of natural intestinal microflora in children with AAEDS and NAAEDS was similar. Hence, there is no evidence of a role of the intestinal microflora with regard to the development of infant (food) allergy in children with AEDS. The possible consequences for allergic diseases later in life require further investigation.

Atopic dermatitis, extrinsic atopic dermatitis and the hygiene hypothesis: results from a cross-sectional study

BACKGROUND

Atopic Dermatitis (AD), hayfever and asthma are commonly summarized as atopic diseases. The spatial distribution of AD differs from that of asthma and hayfever, suggesting that AD might follow a different risk pattern than these diseases. AD can be differentiated into an allergic extrinsic form (EAD) and a non-allergic intrinsic form (IAD). Only EAD might follow the distribution and risk pattern that have been ascribed to asthma and hayfever.

OBJECTIVE

To investigate the distribution and risk factor profile of AD and EAD focusing on environmental factors relating to the hygiene hypothesis.

METHODS

Population-based cross-sectional study on 12,601 children aged 5-7 and 9-11 years from Dresden (Eastern Germany) and Munich (Western Germany). Information was obtained by International Study of Asthma and Allergic Childhood questionnaires, dermatological examinations and skin prick testing. AD-diagnosis ever, current AD-symptoms and visible eczema were investigated with their respective extrinsic forms.

RESULTS

Maternal and paternal history of AD were equally strong determinants of the child's AD status. Factors related to the hygiene hypothesis like day-care attendance and number of older siblings were not associated with a decreased risk of AD. The proportion of EAD within AD was higher in Eastern than in Western Germany. The determinants of the diseases appeared to be similar for both EAD and IAD.

CONCLUSIONS

There was no evidence of the hygiene hypothesis holding true for AD or EAD. AD might be a separate entity than respiratory atopic diseases. Little is known about the risk factors of AD and factors different from those of respiratory allergic diseases should be considered in future research.

Diagnosis of allergy syndromes: do symptoms always mean allergy?

Allergic disease has become a major burden in westernized societies because of a recent rise in its prevalence. Approximately one-third of children suffer from an allergic disease, with the prevalence varying from 15 to 20% for atopic dermatitis, 7 to 10% for asthma and 15 to 20% for allergic rhinitis and conjunctivitis. Despite the increase, it is important not to assume a diagnosis of allergy on the basis of symptoms alone, because allergic and nonallergic conditions may present with similar symptoms. An accurate allergy diagnosis is important in order to treat the patient most appropriately and to potentially prevent or delay the development of allergic disease. A good clinical history is the starting point for accurate allergy diagnosis but is not unequivocal. The European Academy of Allergy and Clinical Immunology has recognized the importance of allergy testing and therefore developed evidence-based recommendations on allergy testing in children. Widespread adherence to these recommendations should improve the quality of care for allergy patients. Cooperation between all healthcare professionals involved in the treatment of allergy patients is also a key to improve our response to the allergy epidemic.

Improving the management of atopic disease

Asthma, wheeze, eczema, and, to a certain extent, rhinitis are very common conditions among children. The prevalence of allergic disease in the general population has increased alarmingly over the past 25 years, particularly in Western industrialised countries. However, it is important to remember that the symptoms often associated with allergy can have other aetiologies. Evidence suggests that in most circumstances, only 30-40% of chronic allergic-type symptoms are due to allergy. Accurate diagnosis of the presence of allergy is therefore an important issue, particularly given the interventions that such a diagnosis may initiate. In this review, we examine management options for allergy, provide the evidence as to what proportions of patients with common allergic-type symptoms are actually allergic, and list other causes of such symptoms. The importance of allergy testing and the options available are described, particularly with reference to the role of the non-allergist.

Worm infestation and the negative association with eczema (atopic/nonatopic) and allergic sensitization

BACKGROUND

Worm infestations may play a role in preventing allergies. There is a lack of epidemiological information from Western countries on the association between worm infestation and eczema.

OBJECTIVE

To investigate the association between worm infestation and eczema in a proper temporal sequence and under consideration of allergic sensitization.

METHODS

Two surveys were performed in East German school children. Questionnaire data included the history of eczema and worm infestation and their time of onset. Specific IgE antibodies to five common aeroallergens were measured and used to define nonatopic and atopic eczema. Logistic regression analyses were performed to control for relevant confounders (age, sex, parental school education and history of allergies). In order to confirm the findings a corresponding conditional regression analysis was applied on cases and controls matched by age and sex.

RESULTS

A total of 4169 children participated (response 75 and 76%) who were, on average, 9.2 years old (47% girls). Overall 17.0% reported a prior worm infestation (Ascaris 44%, Oxyuris 33%) and 18.1% had a history of eczema. Eczema occurred significantly less frequent in children who had a worm infestation (prior to the onset of eczema) compared with children without such a history (8.1%vs 16.5%, OR(adj): 0.45, 95% CI: 0.33-0.60). The finding was confirmed by the corresponding matched case-control analysis (OR(adj): 0.57, 95% CI: 0.41-0.79). Atopic eczema was affected more by a prior worm infestation (OR(adj): 0.31, 95% CI: 0.18-0.56) than the nonatopic eczema (OR(adj): 0.58, 95% CI: 0.40-0.84). A total of 29.1% exhibited specific IgE antibodies to at least one aeroallergen. Sensitized children gave significantly less frequent a history of worm infestation (14.2%vs 18.3%, OR(adj): 0.74, 95% CI: 0.60-0.92). Stratified analysis revealed that this effect most pronounced for a sensitization to house dust mite.

CONCLUSIONS

A worm infestation is associated with a reduced frequency of subsequent eczema, especially the atopic type. Furthermore allergic sensitization, especially to house dust mite, and worm infestation are negatively associated. The data support the concept that a lack of immune-stimulation by parasitic infections contributes to the development of allergies.

Atopic sensitization and atopic dermatitis in Estonian and Swedish infants

BACKGROUND

Early life events seem to have a major impact on the development of tolerance or sensitization.

OBJECTIVE

The aim of the study was to compare the prevalence of sensitization and atopic dermatitis (AD) during the first 2 years of life in Estonia and in Sweden.

METHODS

Two groups comprising 110 Estonian and 123 Swedish infants were followed from birth up to 2 years of age. Data about symptoms of allergy, infections and use of antibiotics were obtained by questionnaires. Clinical examinations, skin prick tests (SPTs) with food and inhalant allergens, and blood sampling for IgE analyses were carried out at 3, 6, 12 and 24 months.

RESULTS

The cumulative incidence of AD and positive SPTs were lower in the Estonian than the Swedish infants (14% vs. 24%; P = 0.06 and 13% vs. 24%; P = 0.03), while circulating IgE antibodies were more common (39% vs. 27%; P = 0.06) and often present without any clinical significance in Estonian children. Estonian infants had respiratory illnesses more often and they had received antibiotics more frequently. Use of antibiotics increased the risk for positive SPT in the Estonian (odds ratio = 1.7, 95% confidence interval = 1.1-2.5), but not in the Swedish infants. This may be explained by the use of broad-spectrum antibiotics in Estonia, while in Sweden mostly penicillin was prescribed.

CONCLUSIONS

The prevalence of AD and positive SPTs was lower in the Estonian than the Swedish infants, while circulating IgE antibodies were more common and often present without any clinical significance. These differences cannot simply be explained by infections, or use of broad-spectrum antibiotics in the two countries, although more the natural lifestyle in Estonia may be contributing factor.

Antigen specific cytokine response in pediatric patients with atopic dermatitis

The physiopathology of atopic dermatitis (AD) has still to be elucidated. T effector cells with cutaneous homing receptors or T-cell derived cytokines have been assumed to be implicated in the pathogenetic mechanisms in AD and to be responsible for the different immunologic responses of patients. In fact, the large majority of AD patients display high IgE levels while others do not develop an abnormal IgE response. Although, there are not significant clinical features characterizing the two different groups, patients with normal IgE belong to a younger age range, raising the possibility that the hypothesized dichotomy of AD might be due to age. In the present study we included 172 outpatient children attending the Pediatric Department of our institution. Serum IgE levels and percentages of peripheral T lymphocytes expressing the cutaneous homing antigen (CLA) were evaluated and results were analyzed in relation to the activity of the disease (SCORAD index) or age. In the overall patients, the IgE levels increased significantly with age (0-1 yr: 19.50 IU/ml; 1-3 yr: 62.0 IU/ml; 3-8 yr: 96.0 IU/ml; >8 yr: 148.5 IU/ml; p<0.001) and with the severity of the disease (SCORAD low: 46.80 IU/ml; medium: 42.90 IU/ml; high: 148.5 IU/ml; p=0.01). Percentages of CLA+ peripheral T lymphocytes also increased with age (0-1 yr: 3.3; 1-3 yr: 4.85; 3-8 yr: 10.6; >8 yr: 12.5; p<0.001), although they were not significantly different in patients with different SCORAD (p=0.89). We further investigated the cellular immune response to a specific antigen in 25 subjects, matched for age, SCORAD, and CLA+ T-cell percentages. Among them, 13 patients had casein serum specific IgE and 12 had no evidence of casein sensitization. Peripheral blood mononuclear cells were kept in short-term culture with endotoxin-free casein fractions and IFN-gamma, TNF-alpha, IL-5, IL-10 cytokine-producing cells were detected by ELISpot. Statistical analysis showed significant higher numbers of TNF-alpha- or IL-10-producing cultures (stimulation index >3) in the 'allergic' patients than in the milk tolerant subjects (p=0.01 and 0.05). The analysis of individual responses confirmed this finding but also provide evidence of a significant increase in IFN-gamma-producing cells (p=0.05) induced by casein stimulation in the group of 'non-allergic' children. Our data showed that immunologic parameters as IgE levels or CLA+ T cells in AD pediatric patients are influenced by the age, confirming that age could represent a bias in the analysis of immune response in those patients. Although, we demonstrated in children with AD the existence of different cytokine patterns of the lymphocyte response that could account for the different immunologic features between the two hypothesized forms of AD, which are not dependent on age.

Socioeconomic differences in the prevalence of common chronic diseases: an overview of eight European countries

BACKGROUND

Few studies have compared socioeconomic inequalities in the prevalence of both fatal and non-fatal diseases. This paper aims to give the first international overview for several common chronic diseases.

METHODS

Micro-level data were pooled from non-standardized national health surveys conducted in eight European countries in the 1990s. Surveys ranged in size from 3700 to 41 200 participants. The prevalence of 17 chronic disease groups were analysed in relation to education. Standardized prevalence rates and age-adjusted odds ratios (ORs) were calculated.

RESULTS

Most diseases showed higher prevalence among the lower education group. Stroke, diseases of the nervous system, diabetes, and arthritis displayed relatively large inequalities (OR > 1.50). No socioeconomic differences were evident for cancer, kidney diseases, and skin diseases. Allergy was more common in the higher education group. Relative socioeconomic differences were often smaller among the 60-79 age group as compared with the 25-59 age group. Cancer was more prevalent among the lower educated in the 25-59 age group, but among the higher educated in the 60-79 age group. For diabetes, hypertension, and heart disease, socioeconomic differences were larger among women as compared with men. Inequalities in heart disease were larger in northern European countries as compared with southern European countries.

CONCLUSION

There are large variations between chronic diseases in the size and pattern of socioeconomic differences in their prevalence. The large inequalities that are found for some specific fatal diseases (e.g. stroke) and non-fatal diseases (e.g. arthritis) require special attention in equity-oriented research and policies.

How atopic is atopic dermatitis?

BACKGROUND

The extent to which the phenotype of atopic dermatitis (AD) is truly atopic has been the subject of much debate.

OBJECTIVE

We sought to systematically evaluate the evidence for the value of measurement of IgE antibodies in diagnosing AD and whether knowledge of IgE sensitization increases clinical diagnostic and predictive ability.

METHODS

We searched Medline from its inception until September 2003. Only studies that measured atopy as either skin prick test positivity or IgE-antibody sensitization to environmental allergens were included within a descriptive analysis. Because the small number of studies of adequate quality did not allow a formal meta-analysis, we assigned strength of evidence according to predefined quality criteria and ranked studies accordingly.

RESULTS

Inclusion of atopy as part of the diagnostic criteria for AD did not enhance the criteria's sensitivity and specificity in relation to the clinical phenotype of AD. The strength of association between atopy and AD varied significantly between hospital studies (47% to 75%; n=14 studies) and was stronger in hospital than in community populations (7.4% to 78%; n=13 studies). Whereas study quality did not have an effect on atopy prevalence in hospital populations, low atopy prevalences in community surveys were seen in less rigidly conducted studies. AD severity was positively associated with the number of positive skin prick test responses or IgE-antibody levels in 7 of 8 studies that measured both. Only one study suggested that IgE-specific sensitization to hen's egg is associated with subsequent development of AD, and 2 studies found that allergen-specific IgE sensitization in patients with AD is a prognostic marker for allergic airway disease in later life. Atopy-associated AD might also have a worse long-term prognosis than AD that is not associated with atopy.

CONCLUSION

Although atopy is clearly associated with AD, the role of IgE sensitization in AD needs further study. Current evidence suggests that up to two thirds of persons with AD are not atopic, which implies that continued use of the term atopic dermatitis is problematic. Longitudinal studies are needed to compare the treatment response and prognosis of IgE-associated and non-IgE-associated AD.

Influences in allergy: epidemiology and the environment

Many decades after the first descriptions of hay fever in the 19th century, we still struggle with the formation of a cogent conception embracing all the many fragments of insight into the various aspects of allergic and asthmatic diseases. Although in daily practice we can grasp and allocate most of the clinical manifestations, in research the fundamental structures are only in part recognized. We therefore presume that the underlying mechanisms are complex and multifaceted. We have explored in countless directions while branching into ever more detailed analyses of phenomena, all of which are associated with the conditions of interest. But how can we rearrange these pieces to advance toward a broader understanding of asthma and allergies? Epidemiology as a scientific tool to study the occurrence, the natural course, and the determinants of a condition in various sociocultural environments might contribute to the edifice of such a scaffold. This review does not intend to present a comprehensive digest of the relevant literature: the reader can refer to other "state of the art" reviews. The intention is to discuss some conceptual cornerstones and to illustrate them with a few examples.

The epidemiology of atopic dermatitis in Italian schoolchildren

BACKGROUND

Atopic dermatitis (AD) is common in children in industrialized countries. Only one large population study on its prevalence has been conducted in Italy, based on self-report questionnaire. The present study was designed to estimate the prevalence of AD in schoolchildren in Italy by dermatologists' assessment and by UK Working Party criteria, and to investigate associated symptoms and factors.

METHODS

Cross-sectional survey on a random sample of 9-year-old schoolchildren from seven Italian cities. Children were examined by experienced dermatologists. Parents and teachers answered standardized questionnaires.

RESULTS

Of the 1369 children examined, 88 had a diagnosis of AD, with an estimated point prevalence of 5.8% (95% CI 4.5-7.1) in the reference population. The reported lifetime prevalence was 15.2 (95% CI 12.2-18.2) for AD, 11.9% (95% CI 9.0-14.8) for asthma, and 17.6% (95% CI 14.6-20.7) for rhino-conjunctivitis. The strongest associated factor was the presence of AD in at least one parent. No association of AD with maternal smoking during pregnancy, birth weight, maternal age at the time of the child birth and breast-feeding was observed. The environmental characteristics of the house and the school did not correlate with the prevalence of AD. Episodes of lower respiratory tract infections were associated with asthma, and to a lower extent also with AD and rhinitis.

CONCLUSIONS

The prevalence of doctor-diagnosed AD in Italian schoolchildren is comparable to those reported for other developed countries. Family history of atopy was the single most important associated factor, while the complex interplay of environmental factors remains to be elucidated.

Atopic dermatitis

Atopic dermatitis is a highly pruritic chronic inflammatory skin disorder affecting 10-20% of children worldwide. Symptoms can persist or begin in adulthood. It is also the most common cause of occupational skin disease in adults. This disease results from an interaction between susceptibility genes, the host's environment, pharmacological abnormalities, skin barrier defects, and immunological factors. New management approaches have evolved from advances in our understanding of the pathobiology of this common skin disorder.