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

Epidemiology of skin diseases in Germany: systematic review of the current state of research - part 2: non-infectious skin diseases

The aim of this work was to systematically collect all previously published population-based epidemiological data on skin diseases in Germany. The present part 2 of the publication series deals with non-infectious skin diseases. The results on cutaneous tumor diseases (part 1) and infectious skin diseases (part 3) form the other parts of this publication series. A systematic literature search was performed using PubMed/MEDLINE for the period of the last 15 years. With the aim of including all dermatologic diseases, a diagnostic list was developed based on the ICD-11 catalogue. This list included 1,347 skin diseases and formed the basis for the search. The literature search yielded 4,650 hits, of which 72 were included in the synthesis. Among them were 37 publications on non-infectious skin diseases. Among these, psoriasis and atopic eczema were the most common. The highest lifetime prevalence was found for acne. This work is the first systematic literature review that aimed to report all available epidemiological data on skin diseases in Germany. It was found that representative data on many non-infectious diseases are not yet available. Among the included studies, there was a high heterogeneity regarding the methodology. Nevertheless, the utility of these epidemiological data is wide-ranging and can serve as a reference of various epidemiological questions.

Atopic diseases and airway-related symptoms in Bavarian children before starting primary school: Time trend analyses

BACKGROUND

After decades of rising prevalence of atopic and airway-related diseases, studies showed stagnating prevalence in western industrialised countries. Objective of this study is to analyse the time trend of prevalence of atopic diseases and airway-related symptoms among Bavarian children before starting primary school.

MATERIALS AND METHODS

Five cross-sectional studies from 2004/2005, 2006/2007, 2012/2013, 2014/2015 and 2016/2017 took place in urban and rural regions in Bavaria, Germany. Using standardized parent questionnaires children's atopic diseases and airway-related symptoms were surveyed. Logistic regression analysis (Bonferroni correction: adjusted significance level 0.005) was performed to analyse prevalence of symptoms and diseases from 2004 to 2017 for time trends.

RESULTS

The surveys included 27384 Bavarian children aged 5-6 years (52.6% male). In all children the calculated 12-month prevalence of symptoms '≥four episodes of wheeze' (p-value = .0880) and 'rhinoconjunctivitis' (p-value = .3994) reported by parents stagnated, whereas 'wheeze' (p-value<.0001; OR = 0.97; CI = [0.96-0.98]) and 'rhinitis' (p-value = .0007; OR = 0.98; CI = [0.97-0.99]) decreased. In all children the calculated lifetime prevalence of physician-diagnosed 'asthma' (p-value = .5337), and 'hay fever' (p-value = .8206) stagnated, whereas of 'bronchitis' (p-value<.0001; OR = 0.98; CI = [0.98-0.99]) decreased over time. The calculated lifetime prevalence of physician-diagnosed 'atopic eczema' (p-value = .0002; OR = 0.98; CI = [0.97-0.99]) decreased in all children, whereas the calculated 12-month prevalence of the symptom 'itchy rash' increased (p-value = .0033; OR = 1.07; CI = [1.05-1.08]) over time.

CONCLUSIONS

Several calculated prevalence of children's atopic diseases and airway-related symptoms reported by parents stagnated in a subgroup of Bavarian children before starting primary school between 2004 and 2017. The time trend of prevalence in 'wheeze', 'rhinitis' and 'bronchitis' decreased. Prevalence of 'atopic eczema' decreased over time, whereas 'itchy rash' increased.

Management of patients with seasonal allergic rhinitis: Diagnostic consideration of sensitization to non-frequent pollen allergens

BACKGROUND

Diagnosis of pollen allergies is mainly based on test allergens for skin prick testing. In the minimum battery of test inhalant allergens recommended by the Global Allergy and Asthma European Network 10 pollen allergens are included. Complementary other pollen allergens may need to be considered; however, respective awareness may not always be granted. Furthermore, at least in Germany, the situation may be even more complicated by the fact that test allergens need regulatory approval. A decline in commercially available test allergens may result in a diagnostic gap regarding patients with non-frequent allergies. How many patients with non-frequent pollen allergies would be affected by this gap? The data presented here partly answer this question.

METHODS

The study consisted of a descriptive and an analytical part. In the descriptive part, sensitization to frequent pollen allergens (alder, hazel, birch, sweet grasses; according to the German Therapy Allergen Ordinance) and to respective non-frequent pollen allergens (cypress, Japanese cedar, ash, plane tree, olive, Bermuda grass, wall pellitory, plantain, goosefoot, mugwort, ragweed, and saltwort) was measured in adult patients with physician-diagnosed allergic rhinitis from two German federal states, namely North-Rhine Westphalia (n = 360) and Bavaria (n = 339), using skin prick testing and/or ISAC technology. Furthermore, respective regional pollen data were assessed. In the analytical part, sensitization data were correlated with each other and with anamnestic data on symptom periods.

RESULTS

Sensitization to frequent pollen allergens ranged from 45% (sIgE to Aln g 1/Alder, NRW) to 72% (prick test reactivity to birch, NRW). Sensitization to non-frequent pollen allergens ranged from 0% (sIgE to Amb a 1/ragweed, NRW) to 41% (prick test reactivity to olive, Bavaria). Sensitization data partly correlated with each other and in connection with symptom periods showed a partly similar seasonal pattern as pollen data.

CONCLUSIONS

Sensitization to non-frequent pollen allergens have to be considered when examining patients with respective seasonal symptoms, and test (and respective therapy) allergens for non-frequent pollen allergies need to be available. Further prerequisites for adequate patient management would be a nationwide pollen monitoring system giving continuous pollen data and a systematic sensitization monitoring at patient level.

[Epidemiology and treatment of adult patients with atopic dermatitis : Analysis of longitudinal data of the statutory health insurance scheme]

BACKGROUND

The goal was to report incidence, prevalence, and treatment patterns in adult atopic dermatitis (AD) patients in the German statutory health insurance system.

PATIENT AND METHODS

Anonymized claims data were evaluated at patient level for 3.3 million persons insured by six different statutory health insurance companies (SHI). Patients for whom the ICD-10 diagnosis code L20 (AD) was applied at least twice were analyzed and data on prescription patterns for AD were reported for the years 2011-2015.

RESULTS

AD prevalence in adults was 1.6-1.9% in 2012-2015. Annual incidence was 0.28%. In Q3/Q4 2015, 44.2% of the adult population with AD diagnosis by a dermatologist received prescriptions for AD medications: 1.6% low-potency topical glucocorticoids (without previous prescription of systemic drugs), 46.9% moderate or high-potency topical glucocorticoids or topical calcineurin inhibitors, 23.9% current systemic therapy (systemic glucocorticoids, ciclosporin, methotrexate, azathioprine, mycophenolate mofetil) and 27.6% systemic therapy in the past.

CONCLUSIONS

The AD prevalence estimate was in the range of previous reports (1.35-4%) that used different methodologies. Based on treatment proxy, it appeared that almost more than half of AD patients treated with prescription ready-to-use drugs had a severe form of AD which required treatment with systemic drugs.

Coaggregation of Asthma and Type 1 Diabetes in Children: A Narrative Review

Asthma and type 1 diabetes mellitus (T1DM) are two of the most frequent chronic diseases in children, representing a model of the atopic and autoimmune diseases respectively. These two groups of disorders are mediated by different immunological pathways, T helper (Th)1 for diabetes and Th2 for asthma. For many years, these two groups were thought to be mutually exclusive according to the Th1/Th2 paradigm. In children, the incidence of both diseases is steadily increasing worldwide. In this narrative review, we report the evidence of the potential link between asthma and T1DM in childhood. We discuss which molecular mechanisms could be involved in the link between asthma and T1DM, such as genetic predisposition, cytokine patterns, and environmental influences. Cytokine profile of children with asthma and T1DM shows an activation of both Th1 and Th2 pathways, suggesting a complex genetic-epigenetic interaction. In conclusion, in children, the potential link between asthma and T1DM needs further investigation to improve the diagnostic and therapeutic approach to these patients. The aim of this review is to invite the pediatricians to consider the potential copresence of these two disorders in clinical practice.

Sensitization rates to common inhaled allergens in Germany - increase and change patterns over the last 20 years

BACKGROUND

Sensitization rates to aeroallergens are rising worldwide. The prevalence is increasing, especially in Western countries. We aimed to investigate (1) sensitization rates and (2) cross-sensitization patterns in skin prick tests (SPTs) for the most relevant inhaled allergens in central Germany over 20 years, adjusted for regional pollen counts.

PATIENTS AND METHODS

This monocentric study evaluated SPTs for tree pollen, grass pollen and house dust mites (HDMs) in 4,315 patients (including children) with suspected airway allergies, from 1998-2017.

RESULTS

Sensitization rates to almost all aeroallergens have increased significantly over time, without relevant changes in regional pollen counts. Current sensitization rates in all our symptomatic patients were highest for grass (55.3 %) and rye pollen (59.6 %), with most pronounced increases in HDM sensitization over time (from 37.8 % to the current figure of 50.1 %). However, a low but consistent proportion of tree-sensitized patients (3.6-7.8 %) showed isolated positive SPTs to alder and/or hazel pollen without sensitization to birch pollen.

CONCLUSIONS

We demonstrate a significant rise in the total number of sensitized patients as well as increases in cross-sensitization between closely related allergens. Individuals with unusual mono-sensitization profiles to common inhaled allergens should be studied in more detail, since these patients are currently excluded from clinical trials for allergen immunotherapy.

Self-Reported Survey on Allergy Symptoms Among First-Year Students in Veterinary Medicine: A Preamble to the AllergoVet Cohort Study

Practical work in veterinary medicine provides exposure to various allergens which could increase the risk of sensitization. With the ongoing prospective "AllergoVet" study, we are investigating patterns of allergic symptoms and sensitization among veterinary students. Here, we report the results of the introductory self-reported survey on the presence of allergies in the first-year students of veterinary medicine, who had begun their studies in the years 2013-2016. The survey included 553 students who answered a questionnaire (63% response rate, 83% female ratio). The median age was 20 years (IQR: 19-22 years). About half of the responders indicated an interest in participating in the prospective study ("candidates"). Those who were uninterested in participating were termed "noncandidates". A doctor's diagnosis of any kind of atopic disease was reported by every fourth student. Hay fever was reported by 71 (13%) and allergic asthma by 38 (6.9%) students. The prevalence of hay fever in "candidates" (n = 294) and "noncandidates" (n = 259) was 13.5% and 12.2%, respectively. Allergic asthma was reported by 9.9% of "candidates" and 3.5% of "noncandidates", the difference being significant (p = 0.003). We conclude that the prevalence of self-reported allergic symptoms in the first-year students of veterinary medicine is similar to that in the general population. Pre-existing allergic asthma may have increased the motivation for the enrolment into the longitudinal "AllergoVet-study".

Diagnosis and treatment of xerosis cutis - a position paper

BACKGROUND AND RATIONALE

Xerosis cutis (also referred to as xeroderma, dry skin, asteatosis) affects more than 10 million individuals in Germany. It is among the most common dermatological diagnoses and a cardinal symptom of many dermatological, internal and neurological diseases. Even though it has been established that basic skin care plays a significant role in the management of patients with xerosis cutis, there are as yet no evidence-based algorithms for diagnosis and treatment.

OBJECTIVE

The present position paper provides physicians across all specialties with a practical, symptom-based approach to the prevention, diagnosis and treatment of xerosis cutis.

METHODS

Within a structured decision-making process, a panel of experienced dermatologists first defined questions relevant to everyday clinical practice, which were then addressed by a systematic review of the literature. Based on the evidence available as well as expert consensus, diagnostic and treatment algorithms were subsequently developed and agreed upon.

RESULTS

Xerosis cutis is generally diagnosed on clinical grounds. Possible trigger factors must be avoided, and comorbidities should be adequately and specifically treated. Suitable skin care products should be chosen with a view to improving skin hydration and restoring its barrier function. They should therefore contain both rehydrating and lipid-replenishing components. The "drier" the skin appears, the greater the lipid content should be (preferably using water-in-oil formulations). The choice of ingredients is based on a patient's individual symptoms, such as scaling (e.g., urea), fissures/rhagades (e.g., urea or dexpanthenol), erythema (e.g., licochalcone A) and pruritus (e.g., polidocanol). Other factors to be considered include the site affected and patient age. Ingredients or rather combinations thereof for which there is good clinical evidence should be preferentially used. The best evidence by far is available for urea, whose efficacy in the treatment of xerosis is further enhanced by combining it with other natural moisturizing components and ceramides. The "xerosimeter" is a tool developed in an effort to facilitate patient management and for training purposes. It not only includes practical tools for diagnosis and follow-up but also a classification of ingredients and a structured treatment algorithm.

CONCLUSION

The structured symptom- and evidence-based approach proposed herein contains a road map for diagnosis and treatment of xerosis cutis. It aims to raise awareness in terms of prevention and early treatment of this condition and may thus improve quality of life and prevent potential sequelae.

"New" inhalant plant allergens

Specific IgE measurements obtained from patients suffering from respiratory allergy (n = 952) show that, despite similar climatic conditions, there are clear regional differences in pollen sensitization between North Rhine-Westphalia and Bavaria. The data on sensitization levels and pollen concentration was taken from the research and development project Ufoplan 3710 61 228 of the German Environment Agency for North Rhine-Westphalia and Bavaria (2011 - 2014). Most poly-sensitized patients have already shown sensitization, both in the form of cross-reactivity and species-specific sensitization, to "new" pollen allergens, such as Bermuda grass and olive tree. These plants are currently not common in Germany, but may become considerably more widespread due to the increase in average yearly temperatures caused by the global warming. The other "new" aeroallergens discussed here are plants that can be found throughout Germany, such as nettle, cypress, and pine. Their current sensitization levels are higher than 8%; however, their clinical impact appears to be underestimated. For clinical practice it is important to identify when patients' symptoms are typically severe and which regional plants might be responsible for the patients' complaints in this period of time, as this affects further diagnostic strategy. Allergens having an immune effect can then be targeted by specific immunotherapies. The information on complaints of the patients should be regularly recorded in symptom diaries. Recording this information for at least 1 year may allow to discover a correlation between specific types of pollen and allergy symptoms.

Overweight Proxies Are Associated with Atopic Asthma: A Matched Case-Control Study

BACKGROUND

Many studies have documented a link between overweight and asthma in children with contradictory results regarding the best way to measure overweight. Moreover, often, the dynamic development of atopy, overweight, and asthma is controlled for age dependency insufficiently.

OBJECTIVE

This study assesses and compares the associations of overweight measured as waist circumference, waist to height ratio (WHtR), neck circumference, and body mass index with the occurrence of asthma - best possibly controlling for age-dependencies of these parameters.

METHODS

From a sample of 2,511 children aged 6-17 years, we matched 157 children with asthma with 2 controls (n = 471) according to age and atopy status and performed conditional logistic regression analyses. We further investigated the role of known influencing factors of asthma occurrence.

RESULTS

In children with atopy, all overweight proxies were consistently positively associated with asthma. Statistical significance was reached for WHtR-SD score (OR 1.26, 95% CI 1.03-1.54, p = 0.025) and persisted when further covariates, such as birth weight or social status, were added to the model. Groups of atopic versus nonatopic participants do not differ in levels of interleukin-6 or high-sensitivity C-reactive protein.

CONCLUSION

In our cohort, overweight seems to carry a risk for asthma only if accompanied with atopy. We call for more strict age matching in pediatric cohort studies and longitudinal studies for a better understanding for causal links of overweight, atopy, and asthma.

Trends and regional distribution of outpatient claims for asthma, 2009-2016, Germany

OBJECTIVE

To investigate asthma morbidity in Germany by calculating current prevalence, examining its temporal and spatial trends and estimating the total number of asthmatics in Germany and calculating age-, sex- and residence-specific risk.

METHODS

We used claims data reported by physicians during 2009-2016, including outpatient diagnoses of all statutory health insured individuals, comprising 85.3% (70 416 019/82 521 653) of the total population in Germany in 2016. We performed a spatial analysis of asthma prevalence according to administrative district by calculating Global and Local Moran's I. We assessed the risk of asthma by sex, age, type of residence (rural versus urban) and federal state (East versus West) using a multilevel parametric survival regression.

FINDINGS

We estimated that 4.7 million individuals were affected by asthma in 2016, including 0.8 million children and 3.9 million adults. We observed a slightly higher prevalence (with an increasing trend) among adults (5.85%; 3 408 622/58 246 299) compared to children (5.13%; 624 899/12 169 720), and calculated an age-standardized prevalence of 5.76% (95% confidence interval, CI: 5.76-5.77). We found evidence of a strong spatial autocorrelation (Global Moran's I: 0.50, P < 0.0001), and identified local spatial clusters with higher levels of prevalence. Living in the western (versus eastern) federal states and living in densely populated large urban municipalities (versus rural area) were independently associated with an increased risk of asthma, with hazard ratios of 1.33 (95% CI: 1.32-1.34) and 1.32 (95% CI: 1.31-1.32), respectively.

CONCLUSION

Our insights into the spatial distribution of asthma morbidity may inform public health interventions, including region-specific prevention programmes and control.

Prospective comparison of a nonmodified and a modified mite extract for immunotherapy in children and adolescents

Aim: This prospective study compares nonmodified and modified house dust mite extracts for allergen immunotherapy (AIT) in pediatric patients with allergic asthma. Materials & methods: Total 95 patients underwent bronchial allergen provocation (BAP). AIT was recommended to 62 patients. Complete datasets of 54 subjects were obtained. Primary aim was the comparison of treatment success defined by BAP between two extracts after 1 year. Secondary parameters were laboratory parameters and clinical symptoms. Results: Significant improvement (p < 0.001) was measured by BAP in both treatment groups. No change was seen in the controls. Both extracts exerted comparable effects on all parameters. Conclusion: After 1 year of AIT, the extracts were equally efficient, with significant improvements in 70.0% (nonmodified) and 72.2% (modified) of patients.

Residential crowding and asthma in preschool children, a cross-sectional study

BACKGROUND

Asthma is the most common chronic disease in children, and associations with crowding have been reported. The aim of this study was to explore possible associations of crowding with asthma in children.

METHODS

Seven cross-sectional surveys with preschool children were conducted within the framework of the health monitoring units in Bavaria, Germany, from 2004 to 2014. Residential crowding was defined as habitation of more than one person per room or less than 20m² living space per person. Logistic regression models examined temporal changes in crowding, applying the first survey as reference. The relationship between crowding and physician-diagnosed asthma, asthma defined by the International Study of Asthma and Allergies in Childhood (ISAAC) and asthma symptoms were analyzed.

RESULTS

Analyzing temporal changes of crowding rates did not reveal any differences over the years. However, the stratified descriptive analysis indicated a crowding increase in time in urban households where parents had a low education level (47.9% in 2004/05, 55.8% in 2014/15). No association was found between crowding and the variables "physician-diagnosed asthma" in 2014/15, "asthma defined by ISAAC" in 2014/15, or "wheezing" in 2014/15. A positive association with cough was identified in 2014/15 after adjusting for confounders (aOR=1.42 [95% CI: 1.20-1.69]).

CONCLUSIONS

In general, residential crowding did not change from 2004 to 2014; however, there seems to be a small upsurge for children with low-educated parents, living in urban areas over the years. A statistically significant association between crowding and cough was only found in the survey from 2014/15.

[Costs of allergic diseases and saving potential by allergen-specific immunotherapy : A personal assessment]

BACKGROUND

The burden of allergic diseases is of particular relevance for the economy and the social welfare and health insurance framework. Allergic rhinitis (AR) has a life-time prevalence of approximately 30% and is one of the most common chronic diseases with considerable socioeconomic impact thus leading to substantial direct, indirect and intangible costs. This article explores the common hypothesis that allergen-specific immunotherapy (ASIT) saves national economic expenses in the long term in comparison to other standard symptomatic treatment or no therapy.

METHODS

We conducted a selective search and analysis of the literature in PubMed and Medline including otherwise listed publications in German. Using a predefined model and data extrapolation over 9 years for data from different sources and short-term clinical studies we further discuss the problems and difficulties in analyzing heterogeneous datasets.

RESULTS

Using a health-economic model with currently available and accepted variables ASIT proves to be cost-effective in comparison to symptomatic treatment in allergic rhinitis; however, numerous parameters from other models have to be controlled, such as adherence to therapy and therapy discontinuation, heterogeneous costs for different treatment modalities, effect sizes with respect to symptoms including cross-influences with symptomatic rescue medication, duration of efficacy after treatment discontinuation and asthma protection.

DISCUSSION

The personal appraisal of the authors demonstrates not only the current knowledge but also the problems in health economical evaluation of ASIT in allergic diseases.

[Perspectives for nationwide pollen monitoring in Germany]

Allergenic pollen are natural, biological airborne particles and the main cause of allergic respiratory diseases. The measurement of allergenic pollen is a required measure in preventive healthcare and indicates changes in the pollen spectrum as to be expected in the context of climate change.The only nationwide pollen measuring network in Germany is operated by the Foundation German Pollen Information Service, however, its continuity and further development (a hybrid system with manual and automated pollen traps) are not financially guaranteed. In the summer of 2017, the interdisciplinary working group "National Pollen Monitoring" was formed to exchange corresponding perspectives for Germany.Between November 2017 and June 2018, the working group met for three days of discussions, each with a different topic. The internal protocols for each meeting served as a basis for the position paper, which the working group used to complete their work.Due to the impact of allergenic pollen on human health and the significance of allergic diseases for the health service, the working group is in favour of the nationwide pollen monitoring being included in the catalogue of government responsibilities, which secure the basic supply of essential goods and public services of general interest.Regarding any possible assigned responsibilities within the governmental framework, different options were discussed. Independent from future responsibilities, co-operation between metrological, medical and scientific facilities is essential for adequate preventive healthcare.

Air pollutants and primary allergy prevention

Background

Air pollutants such as particulate matter (PM2.5) and nitrogen dioxide (NO2) in outdoor air have long been suspected of causing the development of asthma and allergic rhinitis. However, a variety of systematic reviews have reached different conclusions in the last 15 years on whether these air pollutants do in actual fact play a causal role in the onset of asthma, allergic rhinitis, and eczema.

Methods

Based on published systematic reviews and the most recent publications, the current state of knowledge on epidemiological evidence is presented and the potential for primary prevention of these allergic diseases by reducing or avoiding exposure to these air pollutants evaluated.

Results

Despite conducting an extensive literature search, analyzing the most recent results, and focusing on the birth cohort studies most relevant to the question in hand, epidemiological results do not adequately support the concept of a causal relationship between the two air pollutants in question, PM2.5 and NO2, and asthma. Epidemiological studies predominantly show no effect of these air pollutants on allergic sensitization and the onset of allergic rhinitis. The small number of studies that have investigated the link between air pollutants and eczema largely revealed there to be no link.

Conclusion

If the evidence for the causal role of air pollutants in the onset of allergies is inconclusive, one must assume that it is probably not possible to achieve primary prevention of allergies by improving air quality. However, there is sufficient evidence to show that air pollutants can trigger exacerbations of allergic diseases. This alone justifies ensuring that the existing threshold values for air pollutants are adhered to, in order to protect particularly allergy sufferers from health impairments.

Asthma in children and adolescents with type 1 diabetes in Germany and Austria: Frequency and metabolic control

OBJECTIVE

To investigate the prevalence of asthma in young patients with type 1 diabetes mellitus (T1D) from Austria and Germany and its influence on their metabolic control.

METHODS

This prospective, multicenter observational cohort study was based on the DPV-registry (German/Austrian DPV initiative) including 51 926 patients with T1D (<20 years). All clinical data were documented prospectively. To identify patients with additional asthma, the entry of the diagnosis asthma as well as asthma medication was used for classification.

RESULTS

1755 patients (3.4%) of the cohort had the diagnosis asthma or received asthma-specific drugs. Patients with asthma needed higher insulin doses (0.88 ± 0.3 vs 0.84 ± 0.3 U/kg, P < .01) and had decreased height-standard deviation score (SDS) (-0.002 ± 1.04 vs 0.085 ± 1.02, P < .01); they were more often males (61% vs 52%, P < .01), had an increased body mass index (BMI)-SDS (0.31 ± 0.89 vs 0.28 ± 0.89, P = .04) and experienced more severe hypoglycemia (4.5 [4.2; 4.8] vs 3.2 [3.2; 3.3] events/100 pts. years, P < .01). Glycated hemoglobin A1c (HbA1c) did not differ between patients with and without asthma overall, only sub groups (corticosteroids vs leukotriene antagonist and corticosteroids vs sympatomimetics) revealed differences. No influence of asthma medication on metabolic control or BMI-SDS could be found.

CONCLUSION

In our DPV-database, frequency of asthma and T1D seems similar to the prevalence of asthma in the healthy German background population. The concomitant diagnosis of asthma and T1D had minor influence on metabolic control and diabetes complication rate, although there was no difference in HbA1c overall. Patients with both diseases seem to be slightly growth restricted and require slightly higher insulin doses.

[Climate change - physical and mental consequences]

Climate change has already had a large influence on the human environmental system and directly or indirectly affects physical and mental health. Triggered by extreme meteorological conditions, for example, storms, floods, earth slides and heat periods, the direct consequences range from illnesses to serious accidents with injuries, or in extreme cases fatalities. Indirectly, a changed environment due to climate change affects, amongst other things, the cardiovascular system and respiratory tract, and can also cause allergies and infectious diseases. In addition, increasing confrontation with environmental impacts may cause negative psychological effects such as posttraumatic stress disorders and anxiety, but also aggression, distress and depressive symptoms. The extent and severity of the health consequences depend on individual pre-disposition, resilience, behaviour and adaptation.

Atopy and related clinical symptoms among Swiss medical students from 2007 to 2015

Background

Atopic allergy is a widespread disease with increasing prevalence in the second half of the twentieth century and is most often associated with clinical symptoms, like rhinoconjunctivitis, asthma or eczema. This study explored the prevalence of atopy and polysensitization in nine cohorts of Swiss medical students during the period of 2007-2015. Furthermore, the self-reported allergic symptoms, such as rhinoconjunctivitis, asthma and eczema, among students with and without atopy were assessed.

Methods

Each cohort was assessed in the third study year. Students underwent an ImmunoCAP rapid test, a qualitative point-of-care test, and completed an anonymous questionnaire on age, gender and clinical symptoms including rhinoconjunctivitis, asthma and eczema. Statistical analyses assessed the overall prevalence of atopy in each group and estimated the average annual increase using a linear mixed model. We examined the frequency of occurrence of polysensitization and differences of reported symptoms among students with and without atopy.

Results

Data of 1513 students (mean age 22.4-23.3 years across cohorts) in nine cohorts (median cohort size 215 interquartile range IQR 193-222) were available for analysis. Test results consistent with atopy were present in 39.9% of students. Average increase of atopy over the 9 years of observation was 2.25% (95% CI 0.18-4.31%; p = 0.037). Main drivers for this increase were the ubiquitously available allergens, house dust mite, timothy grass and birch pollen. Atopy and polysensitization were more pronounced in male students: Polysensitization also increased in the observation period. The clinical symptoms, rhinoconjunctivitis, asthma and eczema were reported by 463 (76.7%) atopic and by 141 (15.5%) non-atopic students.

Conclusions

We observed a slight increase of atopy and polysensitization within 9 years of observation in Swiss medical students. The most frequent sensitization occurred with allergens with the highest chance of exposure. Rhinoconjunctivitis, asthma and eczema are a symptom complex associated with atopy but also found in non-atopic students.Trial registration retrospectively registered by the Cantonal Ethics Committee Zurich on 22.01.2016; Nr: 08-2016.

Asthmatic/wheezing phenotypes in preschool children: Influential factors, health care and urban-rural differences

BACKGROUND

Different wheezing and asthmatic phenotypes turned out to indicate differences in etiology, risk factors and health care. We examined influential factors and urban-rural differences for different phenotypes.

METHODS

Parents of 4732 children filled out a questionnaire concerning children's health and environmental factors administered within the Health Monitoring Units (GME) in a cross-sectional study in Bavaria, Germany (2014/2015). To classify respiratory symptoms, five phenotype groups were built: episodic, unremitting and frequent wheeze, ISAAC (International Study of Asthma and Allergies in Children) - asthma and physician-diagnosed asthma (neither of the groups are mutually exclusive). For each phenotype, health care variables were presented and stratified for residence. Urban-rural differences were tested by Pearson's chi-squared tests. Multivariable logistic regression was performed to analyze associations between influential factors and belonging to a phenotype group, and to compare groups with regard to health care variables as outcome.

RESULTS

Risk factors for wheezing phenotypes were male gender (OR = 2.02, 95%-CI = [1.65-2.48]), having older siblings (OR = 1.24, 95%-CI = [1.02-1.51]), and preterm delivery (OR = 1.61, 95%-CI = [1.13-2.29]) (ORs for unremitting wheeze). 57% of children with ISAAC asthma and 74% with physician-diagnosed asthma had performed allergy tests. Medication intake among all groups was more frequent in rural areas, and physician's asthma diagnoses were more frequent in urban areas.

CONCLUSIONS

In accordance with previous research this study confirms that male gender, older siblings and preterm delivery are associated with several wheezing phenotypes. Overall, low numbers of allergy tests among children with physician's diagnoses highlight a discrepancy between common practice and current knowledge and guidelines. Residential differences in health care might encourage further research and interventions strategies.

Epidemiology in Germany-general development and personal experience

Did you ever hear about epidemiology in Germany? Starting from an epidemiological desert the discipline has grown remarkably, especially during the last 10-15 years: research institutes have been established, research funding has improved, multiple curriculae in Epidemiology and Public Health are offered. This increase has been quite steep, and now the epidemiological infrastructure is much better. Several medium-sized and even big population cohorts are ongoing, and the number and quality of publications from German epidemiologists has reached a respectable level. My own career in epidemiology started in the field of environmental health. After German reunification I concentrated for many years on environmental problems in East Germany and observed the health benefits after improvement of the situation. Later, I concentrated on population-based cohorts in newborns (GINI/LISA) and adults (KORA, German National Cohort), and on biobanking. This Essay describes the development in Germany after worldwar 2, illustrated by examples of research results and build-up of epidemiological infractructures worth mentioning.

Vaccinations in the first year of life and risk of atopic disease - Results from the KiGGS study

BACKGROUND

The study focused on the question of whether and - if so - to what direction and extent immunisations in the 1st year may be associated with the risk of being diagnosed with atopic diseases after the 1st year of life.

METHODS

Data from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS, 2003-2006) were analysed. For analyses of potential associations between vaccination status and risk of hay fever, atopic dermatitis or asthma, sample sizes of 15254, 14297, and 15262, respectively, were available.

RESULTS

Children with a sufficient TDPHiHeP vaccination at the end of the 1st year of life had a lower risk of being diagnosed with hay fever after the 1st year of life (adjusted prevalence ratio 0.85, 95% confidence interval 0.76-0.96). Analyses for associations between TDPHiHeP vaccination and risk of atopic dermatitis or asthma, or between age at onset of vaccination or of the number of antigens vaccinated in the 1st year of life and risk of atopic disease failed to yield statistical significance.

CONCLUSIONS

Our results provide no evidence that immunisations in the 1st year of life may increase the risk of atopic disease. If any association exists at all, our results may be interpreted as weakly supportive of the hypothesis that immunisations may slightly decrease the risk of atopy in later life.

GINIplus and LISAplus - Design and selected results of two German birth cohorts about natural course of atopic diseases and their determinants

The increasing prevalence of asthma, hay fever, and allergic sensitization in Western Germany after east-west division in 1949 and their rapid increase in East German children after re-unification in 1990 are strong indications for the role of life-style and/or environmental factors in the development of atopic diseases. Obviously, the perinatal period is crucial for priming the immune system. Therefore, explorations of determinants of atopic diseases need pregnancy or birth cohorts as the most appropriate epidemiological study designs. This review presents the design and selected results of the two German birth cohorts GINIplus and LISAplus. GINIplus and LISAplus recruited 5.991 and 3.097 healthy, term newborns, respectively, from Munich, Wesel, Leipzig, and Bad Honnef. Approximately 55% could be followed for the first 10 years. We analyzed the natural course of atopic diseases and the role of life-style, environmental, and genetic factors for disease onset, intermediate phenotypes, and genes involved in detoxification and oxidative stress. The results of these two large birth cohorts contributed substantially to the understanding of atopic diseases and their determinants.

[Respiratory and allergic diseases of children : Temporal trends, urban-rural differences, and in association with environmental tobacco smoke exposure]

BACKGROUND/OBJECTIVES

Ten years after the establishment of health monitoring units (GME) in Bavaria, temporal trends and urban-rural differences in parent-reported respiratory and allergic diseases as well as environmental tobacco smoke (ETS) exposure in preschoolers were analyzed in an explorative manner. Furthermore, associations between diseases and ETS exposure were studied.

METHODS

Parent questionnaires were used as part of the school entrance examination in two cross sectional studies (S1:2004/2005, n ₁ = 6350; S2:2012/2013, n ₂ = 5052). Temporal trends and urban-rural-differences were tested by X² tests. Associations between diseases and exposures were studied using multiple logistic regression analysis.

RESULTS

The lifetime prevalence of atopic dermatitis declined from S1-S2 from 12.4 to 11.1 %, whereas those for hay fever, asthma, bronchitis and pseudocroup remained stable. In S1 and S2, bronchitis was less often reported in cities. The other diseases showed no urban-rural differences. The prevalence of children's ETS exposure at home declined from S1-S2 from 14.3 to 7.2 % and was generally higher in cities than in rural regions. There was no positive association between diseases and children's ETS exposure at home. In S2 an association was found between asthma and current parental smoking (OR = 1.60; 95 % CI = (1.10-2.32)).

CONCLUSION

The GME provide important data for regional distribution of respiratory and allergic diseases and ETS exposure of preschoolers in Bavaria. The results of the study are important for further development of questionnaires, which will be used in future GME.

A novel experimental technology for testing efficacy of air purifiers on pollen reduction

Background

Allergenic pollen exposure is mostly seen as an outdoor phenomenon but studies have shown an indoor exposure: different pollen species including birch and grass pollen in houses, schools, and shops are leading to long-lasting symptoms even after the pollen season because pollen settle on surfaces and re-enter the indoor air depending on ventilation. To reduce indoor pollen load, windows need to be closed and devices should be used: as pure wiping and cleaning of surfaces is mostly not sufficient, air cleaners may be helpful in reducing pollen counts in indoor environment.

Objective

The efficacy of an air cleaner is usually described by the filtration rate of standard dust particle sizes which is not necessarily related to clinical efficacy.

Methods

A novel study design was developed using the technical equipment of a new mobile exposure chamber to investigate participants with allergic rhinitis (individual observational, controlled, prospective, single arm study).

Results

The tested air cleaner reduced the grass pollen-induced (4000 grass pollen/m³ over 90 min) nasal symptoms (total nasal symptom score) significantly from 6 and 4 points (1st and 2nd exposure in sham run) to less than 1 point when air cleaner was activated.

Conclusions

The novel study protocol is suitable for testing efficacy of air cleaners and the tested air cleaner is effective in reducing clinical symptoms due to grass pollen in an indoor environment.

Allergy and school: nothing to be sneezed at!: A primary school project in Bielefeld, Germany, on epidemiology and health promotion in allergic diseases

Background:

Allergic diseases account for the largest proportion of chronic diseases in childhood and adolescence and place a significant burden on everyday family, social, and in particular school life. Without appropriate education, affected individuals often have little of the knowledge required to understand and deal safely with their allergic disease, and their social environment (school) generally offers insufficient information. An interdisciplinary project involving the Bielefeld Community Foundation (“Bielefelder Bürgerstiftung”), the Children’s Center Bethel, and the local school authority investigated the current knowledge, possibilities for increasing that knowledge, as well as pupils’ and teachers’ perception of the problems experienced by fellow pupils, while at the same time collecting current prevalence figures on allergic diseases among primary school children.

Methods:

All Bielefeld primary schools were invited to participate in the 3 years between 2008 and 2010. A teaching session on allergic diseases held by specialists from the pediatric hospital formed the core of the project. A standardized survey of children – which also addressed non-affected children for the first time in Germany – on the effects of, their knowledge of, and their attitudes toward allergic diseases, as well as an assessment of their quality of life (cross-sectional study), was conducted prior to and following each session. Parents were also surveyed.

Results:

In all, 24 schools per year, each with around 60 classes and 1,250 pupils aged 9 years, took part between 2008 and 2010. Approximately 30 % reported suffering from an allergic disease themselves, of which – with regard to single entries – 16 % were “allergies,” 4 % “asthma,” and 5 % atopic dermatitis. Figures collected from parents were only slightly lower than those from their children. Clear deficits that existed in terms of factual knowledge and/or correct conduct in allergic disease – among affected children as well as in their social environment – prior to the education program were noticeably improved by the teaching session.

Discussion:

The prevalence data gathered here confirm the high numbers recently found in the KiGGS study. Thus, allergic diseases represent a considerable disease risk and potential burden in school children. Providing affected children and their social environment (teachers, fellow pupils) with specialist education can bring about considerable improvements in everyday school life.

Healthcare costs and resource utilization of asthma in Germany: a claims data analysis

INTRODUCTION

Asthma is associated with a substantial economic burden on the German Statutory Health Insurance.

AIMS AND OBJECTIVES

To determine costs and resource utilization associated with asthma and to analyze the impact of disease severity on subgroups based on age and gender.

METHODS

A claims database analysis from the statutory health insurance perspective was conducted. Patients with an ICD-10-GM code of asthma were extracted from a 10% sample of a large German sickness fund. Five controls for each asthma patient matched by age and gender were randomly selected from the same database. Costs and resource utilization were calculated for each individual in the asthma and control group. Incremental asthma-related costs were calculated as the mean cost difference. Based on prescribed asthma medication, patients were classified as intermittent or persistent. In addition, age groups of ≤ 5, 6-18, and >18 years were analyzed separately and gender differences were investigated.

RESULTS

Overall, 49,668 individuals were included in the asthma group. On average, total annual costs per patient were €753 higher (p = 0.000) compared to the control group (€2,168 vs. €1,415). Asthma patients had significantly higher (p = 0.000) outpatient (€217), inpatient (€176), and pharmacy costs (€259). Incremental asthma-related total costs were higher for patients with persistent asthma compared to patients with intermittent asthma (€1,091 vs. €408). Women aged >18 years with persistent asthma had the highest difference in costs compared to their controls (€1,207; p < 0.0001). Corresponding healthcare resource utilization was significantly higher in the asthma group (p = 0.000).

CONCLUSIONS

The treatment of asthma is associated with an increased level of healthcare resource utilization and significantly higher healthcare costs. Asthma imposes a substantial economic burden on sickness funds.

No further increase in the parent reported prevalence of allergies in Bavarian preschool children: Results from three cross-sectional studies

BACKGROUND

After three decades of an increase in the prevalence of asthma and allergies, new findings show a plateau in the prevalence of industrialized nations. The objective of this study was to determine whether there was a change in the parent reported prevalence of asthma and allergies among Bavarian preschool children since 2004.

METHODS

A parent questionnaire was administered as part of the Bavarian school entrance examination in three cross-sectional studies from 2004/2005, 2006/2007 and 2012/2013. The questionnaire included items on allergy testing history, identified allergens, symptoms (e.g. wheezing, itchy eyes, rash), medically diagnosed asthma, hay fever and atopic dermatitis. Logistic regression was performed to observe time patterns and adjust for risk factors.

RESULTS

Data were available for 6350 (2004/2005), 6483 (2006/2007) and 5052 (2012/2013) individuals. Symptoms and diseases were more frequent in boys, except for allergies which affect the skin. From 2004 to 2012 the parent reported prevalence of asthma (2.6% to 2.8%), hay fever (4.7% to 4.0%) and atopic dermatitis (12.4% to 11.1%) either remained quite stable or decreased not significantly.

CONCLUSIONS

Results from these three cross-sectional surveys of parent reports suggest that the parent reported prevalences of asthma and allergies are quite stable with small fluctuations since 2004 for Bavarian preschool children. Future research is needed to determine if this trend will continue.

Current status of allergy prevalence in Germany: Position paper of the Environmental Medicine Commission of the Robert Koch Institute

The lifetime prevalence of allergic diseases in adults in Germany [self-reported doctor diagnosed allergic diseases, Study on Adult Health in Germany (Studie zur Gesundheit Erwachsener in Deutschland, DEGS1, 2008-2011) of the Robert Koch Institute] is 8.6 % for asthma, 14.8 % for hay fever, 3.5 % for atopic dermatitis, 8.1 % for contact dermatitis, 4.7 % for food allergies, and 2.8 % for insect venom allergies. Almost 20 % of German adults are currently affected by at least one allergy. In tests on 50 common single allergens and two mixtures comprising either inhalant allergens or grass pollen allergens, 48.6 % of participants exhibited at least one allergic sensitization (specific IgE antibody detection). Overall, 33.6 % of participants were sensitized to inhalant allergens, 25.5 % to at least one food allergens, and 22.6 % to at least one insect venom allergens. A comparison of data on adults from 1998 [Federal Health Survey 1998 (Bundes-Gesundheitssurvey 1998, BGS98) of the Robert Koch Institute] and 2008-2011 (DEGS1) shows an increase in prevalence over time of almost three percentage points, while the rate of sensitization to inhalant allergens has increased from 29.8 % to 33.6 %. The prevalence of doctor diagnosed hay fever, atopic dermatitis, and food allergies, on the other hand, has remained virtually unchanged over the last 15 years. The Germany-wide lifetime prevalence of allergic diseases in children and adolescents [Study on the Health of Children and Adolescents in Germany (Studie zur Gesundheit von Kindern und Jugendlichen in Deutschland, KiGGS initial survey, 2003-2006) of the Robert Koch Institute] was 4.7 % for asthma, 10.7 % for hay fever, and 13.2 % for atopic dermatitis. Altogether, 40.8 % of German children and adolescents were sensitized to at least one of the inhalant or food allergens measured, while 20.0 % were sensitized to at least one food allergen. A marked increase in hay fever prevalence among East German children in the 1990s has resulted in an alignment of prevalence rates in East and West Germany. In contrast to adults, there was no longer a discernible difference in the prevalence of asthma, hay fever, and allergic sensitization in children between the western and eastern German federal states. In international comparisons with prevalence data from other studies, the participating German centers are in the lower third of the distribution of frequency for both children and adults.

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.

[Chronic and vaccine-preventable diseases in children and adolescents in Germany: results of the KiGGS study: first follow up (KiGGS wave 1)]

The German Health Interview and Examination Survey for Children and Adolescents (KiGGS) 2003-2006 is the first nationwide comprehensive study on the health of children and adolescents living in Germany. The KiGGS first interview follow-up is a telephone interview study that collected, among other things, data on a number of chronic and vaccine-preventable diseases in 2009-2012 and is a combined cross-sectional and longitudinal study based on a population registry sample from the 167 KiGGS study points. The analysis is based on 12,368 respondents (7913 KiGGS follow-up participants aged 7-17 years, response 72 % and 4455 newly recruited 0- to 6-year-olds, response 42 %). Based on parent reports the lifetime prevalence of both chickenpox and pertussis has decreased in the population targeted by recently changed vaccination recommendations. For measles the prevalence remained unsatisfactorily high in each investigated age group. Of the children and adolescents aged 0-17 years 16 % (95 % confidence interval CI 15.2-17.0 %) had a long-standing chronic health condition according to the parents. Of these, however, only one in five was affected in their routine daily activities. The lifetime prevalence in 7- to 17-year-olds was 1.2 % (0.9-1.6) for epilepsy (0.4 % for the past 12 months), 5.0 % (4.4-5.7) for migraine, 0.2 % (0.1-0.3) for diabetes and in 0 to 6-year-olds 2.0 % (1.5-2.6) for heart conditions and 3.1 % (2.5-3.8) for febrile seizures with a -prevalence in 0 to 2-year-olds which are most affected of 1.0 % (0.6-1.6) in the past 12 months. The vast majority of children and adolescents in Germany are in good or very good health as suggested by other results reported in this issue; however, chronic conditions are not rare and need continuous monitoring. These results confirm that implementation of the vaccination recommendations of the German Standing Committee on Vaccination (STIKO) can lead to effective prevention of infectious diseases in Germany.

[Prevalence of common allergies in children and adolescents in Germany: results of the KiGGS study: first follow-up (KiGGS Wave 1)]

The first follow-up of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS Wave 1) was conducted from 2009 to 2012 as a combined cross-sectional and longitudinal study and provides, among other things, data on allergic diseases. Data collection was carried out by telephone interviews. In total, 6,093 girls and 6,275 boys were included, among them 4,455 newly recruited 0- to 6-year-olds (response 38.8%) and 7,913 KiGGS follow-up participants aged 7-17 years (response 72.9%). Based on parent reports, 15.6% (95% confidence interval 14.7-16.5) of children and adolescents aged 0-17 years were currently affected by at least one atopic disease. The 12-month prevalence rates of hay fever, atopic dermatitis, and asthma were 9.1% (8.4-9.8), 6.0% (5.4-6.6), and 4.1% (3.6-4.6), respectively. In all, 2.2% (1.9-2.6) of the children and adolescents were currently suffering from contact dermatitis. Compared with the baseline KiGGS survey from 2003 to 2006, a higher percentage of participants reported the occurrence of asthma within the past 12 months in the recent KiGGS Wave 1 (4.1 vs. 3.2%; p = 0.0034). The total increase is mainly due to higher prevalence rates among 0- to 6-year-olds, especially in girls. Higher 12-month prevalence rates can be also observed for hay fever among 0- to 6-year-olds, especially in girls, although the total increase is not statistically significant (9.1 vs. 8.3%; p = 0.08). There was a declining trend for atopic dermatitis: 6.8% (2003-2006) vs. 5.4% (2009-2012); p = 0.0015.

[Differences in sociodemographic characteristics, health, and health service use of children and adolescents according to their health insurance funds]

Differences in the socioeconomic characteristics and morbidity between members of German private and statutory health insurance funds and also between several statutory health insurances have been shown for adults. We used data from the National Health Survey for Children and Adolescents (KiGGS) to study differences in sociodemographic characteristics, health risks, morbidity, and health service use in child and adolescent insurants of different types of health insurance funds (Ersatzkasse, Allgemeine Ortskrankenkasse, Betriebskrankenkasse , Innungskrankenkasse, other statutory health insurance funds, private health insurance). Differences in the proportion of respondents with a migration background, somatic diseases, psychopathological problems, and contact with a dentist between the different health insurance fund types were found. These results should be considered in studies on health inequalities, which often focus solely on differences between statutory and private health insurance. Our results are also of relevance for health services research using the claims data of health insurance funds.

Body mass index change and atopic diseases are not always associated in children and adolescents

BACKGROUND

Several studies have suggested an association between the increasing prevalence of allergic diseases and dietary factors.

OBJECTIVE

To prospectively explore the association between changes in body mass index (BMI) and symptoms of asthma, rhinitis, rhinoconjunctivitis, and atopic dermatitis to find out whether an increase in BMI increases the risk of developing atopic diseases in adolescence.

METHODS

Comprehensive questionnaires and anthropometric measurements were applied in a random subsample of the International Study of Asthma and Allergies in Childhood phase II (1995-1996, 9 to 11 years of age) in Germany. Of these participants, 1,794 could be followed up in 2002 to 2003 in the Study on Occupational Allergy Risks (16 to 18 years of age). The associations between changes of BMI from baseline to follow-up and incident and persistent respiratory diseases and atopic dermatitis were assessed.

RESULTS

In logistic regression analyses, weight change in either direction was not statistically significantly associated with the incidence or persistence of any of the diseases of interest except for rhinitis. An increase in BMI was linked to an increased risk of incident rhinitis (odds ratio 1.9, 95% confidence interval 1.2-2.9).

CONCLUSION

These results indicate a nonsignificant trend between increased body weight and risk of atopic diseases. Aside from limitations owing to a small subgroup of obese participants and questionnaire-based asthma diagnosis, reasons might be related to an interaction between BMI and hormonal influences, age, and duration and severity of overweight. The results underline that BMI does not necessarily play a decisive role in the course of atopic diseases in all populations.

A systematic review on the development of asthma and allergic diseases in relation to international immigration: the leading role of the environment confirmed

BACKGROUND

The prevalence of asthma and allergic diseases is rising worldwide. Evidence on potential causal pathways of asthma and allergies is growing, but findings have been contradictory, particularly on the interplay between allergic diseases and understudied social determinants of health like migration status. This review aimed at providing evidence for the association between migration status and asthma and allergies, and to explore the mechanisms between migration status and the development of asthma and allergies.

METHODS AND FINDINGS

Systematic review on asthma and allergies and immigration status in accordance with the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The pooled odds ratio (OR) of the prevalence of asthma in immigrants compared to the host population was 0.60 (95% CI 0.45-0.84), and the pooled OR for allergies was 1.01 (95% CI 0.62-1.69). The pooled OR for the prevalence of asthma in first generation versus second generation immigrants was 0.37 (95% CI 0.25-0.58). Comparisons between populations in their countries of origin and those that emigrated vary depending on their level of development; more developed countries show higher rates of asthma and allergies.

CONCLUSIONS

Our findings suggest a strong influence of the environment on the development of asthma and allergic diseases throughout the life course. The prevalence of asthma is generally higher in second generation than first generation immigrants. With length of residence in the host country the prevalence of asthma and allergic diseases increases steadily. These findings are consistent across study populations, host countries, and children as well as adults. Differences have been found to be significant when tested in a linear model, as well as when comparing between early and later age of migration, and between shorter and longer time of residence.