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Residential greenness, respiratory symptoms and lung function in children, adolescents and adults with asthma: A cross-sectional study
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Several studies have demonstrated an association between the risk asthma/allergic rhinitis and the environment. However, to date, no systematic review or meta-analysis has investigated these factors. We conducted a systematic review and meta-analysis to assess the association between urban/rural living and the risk of asthma and allergic rhinitis. We searched the Embase and Medline databases for relevant articles and included only cohort studies to observe the effects of time-lapse geographical differences. Papers containing information on rural/urban residence and respiratory allergic diseases were eligible for inclusion. We calculated the relative risk (RR) and 95% confidence interval (CI) using a 2 × 2 contingency table and used random effects to pool data. Our database search yielded 8388 records, of which 14 studies involving 50,100,913 participants were finally included. The risk of asthma was higher in urban areas compared to rural areas (RR, 1.27; 95% CI, 1.12-1.44, p < 0.001), but not for the risk of allergic rhinitis (RR, 1.17; 95% CI, 0.87-1.59, p = 0.30). The risk of asthma in urban areas compared to rural areas was higher in the 0-6 years and 0-18 years age groups, with RRs of 1.21 (95% CI, 1.01-1.46, p = 0.04) and 1.35 (95% CI, 1.12-1.63, p = 0.002), respectively. However, there was no significant difference in the risk of asthma between urban and rural areas for children aged 0-2 years, with a RR of 3.10 (95% CI, 0.44-21.56, p = 0.25). Our study provides epidemiological evidence for an association between allergic respiratory diseases, especially asthma, and urban/rural living. Future research should focus on identifying the factors associated with asthma in children living in urban areas. The review was registered in PROSPERO (CRD42021249578).
Limited number of studies have focused on the impact of pollen exposure on asthma. As a part of the EAACI Guidelines on Environment Science, this first systematic review on the relationship of pollen exposure to asthma exacerbations aimed to bridge this knowledge gap in view of implementing recommendations of prevention. We searched electronic iPubMed, Embase, and Web of Science databases using a set of MeSH terms and related synonyms and identified 73 eligible studies that were included for systemic review. When possible, meta‐analyses were conducted. Overall meta‐analysis suggests that outdoor pollen exposure may have an effect on asthma exacerbation, but caution is needed due to the low number of studies and their heterogeneity. The strongest associations were found between asthma attacks, asthma‐related ED admissions or hospitalizations, and an increase in grass pollen concentration in the previous 2‐day overall in children aged less than 18 years of age. Tree pollen may increase asthma‐related ED visits or admissions lagged up to 7‐day overall in individuals younger than 18 years. Rare data show that among subjects under 18 years of age, an exposure to grass pollen lagged up to 3 days may lower lung function. Further research considering effect modifiers of pollen sensitization, hay fever, asthma, air pollution, green spaces, and pre‐existing medications is urgently warranted to better evaluate the impacts of pollen on asthma exacerbation. Preventive measures in relation to pollen exposure should be integrated in asthma control as pollen increase continues due to climate change.
The environment plays an instrumental role in the developmental origins of health and disease. Protective features of the environment in the development of asthma and atopy have been insufficiently studied. We used data from the CHILD (Canadian Healthy Infant Longitudinal Development) Cohort Study to examine relationships between living near natural green spaces in early infancy in Edmonton, AB, Canada and the development of atopic sensitization at 1 year and 3 years of age in a cohort of 699 infants, and whether these associations were mediated by infant gut microbiota (measured using 16s V4 amplicon sequencing) at 4 months. The Urban Planning Land Vegetation Index (uPLVI) map of the City of Edmonton was used to assess infants’ exposure to natural spaces based on their home postal codes, and atopic sensitization was assessed using skin prink testing (SPTs) for common food and inhalant allergens. Our findings suggest there is a protective effect of natural green space proximity on the development of multiple inhalant atopic sensitizations at 3 years (odds ratio = 0.28 [95% CI 0.09, 0.90]). This relationship was mediated by changes to Actinobacteria diversity in infant fecal samples taken at 4 months. We also found a positive association between nature proximity and sensitization to at least one food or inhaled allergen; this association was not mediated by gut microbiota. Together, these findings underscore the importance of promoting natural urban greenspace preservation to improve child health by reducing atopic disease susceptibility.
IMPORTANCE Our findings highlight the importance of preserving natural green space in urban settings to prevent sensitization to environmental allergens and promote early-life gut microbiota pathways to this health benefit. These findings support a mediating role of gut microbiome compositions in health and disease susceptibility. This study used unique, accurate, and comprehensive methodology to classify natural space exposure via a high-resolution topographical map of foliage subtypes within the City of Edmonton limits. These methods are improvements from other methods previously used to classify natural space exposure, such as the normalized density vegetation index from satellite imagery, which is not able to distinguish anthropogenic from green space. The use of these methods and the associations found between natural green space exposure and atopic sensitization outcomes support their use in future studies. Our findings also provide many avenues for future research including longer term follow up of this cohort and investigation of a causal role of reduced Actinobacteria diversity on atopic sensitization development.
The presence of urban greenspace may lead to reduced personal exposure to air pollution via several mechanisms, for example, increased dispersion of airborne particulates; however, there is a lack of real-time evidence across different urban contexts. Study participants were 79 adolescents with asthma who lived in Delhi, India and were recruited to the Delhi Air Pollution and Health Effects (DAPHNE) study. Participants were monitored continuously for exposure to PM2.5 (particulate matter with an aerodynamic diameter of less than 2.5 μm) for 48 hours. We isolated normal day-to-day walking journeys (n = 199) from the personal monitoring dataset and assessed the relationship between greenspace and personal PM2.5 using different spatial scales of the mean Normalised Difference Vegetation Index (NDVI), mean tree cover (TC), and proportion of surrounding green land use (GLU) and parks or forests (PF). The journeys had a mean duration of 12.7 (range 5, 53) min and mean PM2.5 personal exposure of 133.9 (standard deviation = 114.8) μg/m³. The within-trip analysis showed weak inverse associations between greenspace markers and PM2.5 concentrations only in the spring/summer/monsoon season, with statistically significant associations for TC at the 25 and 50 m buffers in adjusted models. Between-trip analysis also indicated inverse associations for NDVI and TC, but suggested positive associations for GLU and PF in the spring/summer/monsoon season; no overall patterns of association were evident in the autumn/winter season. Associations between greenspace and personal PM2.5 during walking trips in Delhi varied across metrics, spatial scales, and season, but were most consistent for TC. These mixed findings may partly relate to journeys being dominated by walking along roads and small effects on PM2.5 of small pockets of greenspace. Larger areas of greenspace may, however, give rise to observable spatial effects on PM2.5, which vary by season.
Growing up on a farm is associated with an asthma-protective effect, but the mechanisms underlying this effect are largely unknown. In the Protection against Allergy: Study in Rural Environments (PASTURE) birth cohort, we modeled maturation using 16S rRNA sequence data of the human gut microbiome in infants from 2 to 12 months of age. The estimated microbiome age (EMA) in 12-month-old infants was associated with previous farm exposure (β = 0.27 (0.12–0.43), P = 0.001, n = 618) and reduced risk of asthma at school age (odds ratio (OR) = 0.72 (0.56–0.93), P = 0.011). EMA mediated the protective farm effect by 19%. In a nested case–control sample (n = 138), we found inverse associations of asthma with the measured level of fecal butyrate (OR = 0.28 (0.09–0.91), P = 0.034), bacterial taxa that predict butyrate production (OR = 0.38 (0.17–0.84), P = 0.017) and the relative abundance of the gene encoding butyryl–coenzyme A (CoA):acetate–CoA-transferase, a major enzyme in butyrate metabolism (OR = 0.43 (0.19–0.97), P = 0.042). The gut microbiome may contribute to asthma protection through metabolites, supporting the concept of a gut–lung axis in humans.
Paediatric Asthma contributes in paediatric global burden of diseases, as the most common chronic disease in children. Children are exposed to many environmental risk-factors, able to determine or worsen respiratory diseases, and contributing to asthma and asthma-like symptoms increases, especially in metropolitan areas. In urban settings, surrounding vegetation (greenness) may provide important benefits to health, including the promotion of physical activity and the mitigation of air and noise pollution. The aim of this study was to investigate the association between greenness and respiratory health. A total of 187 children (10–13 yrs old) were recruited in Turin, the north-western part of Italy. The prevalence of asthma and asthma-like symptoms was calculated from self-reported data collected by SIDRIA questionnaire. Spirometry test was performed to obtain respiratory flow measurements. Greenness was measured at individual level through the Normalised Difference Vegetation Index (NDVI) estimations from remote-sensing images. Higher exposure (3rd tertile vs. 1st tertile) to NDVI was associated to significantly lower ORs for asthma [0.13 CI 95% 0.02–0.7, p = 0.019], bronchitis [0.14 CI 95% 0.05–0.45, p = 0.001], and current wheezing [0.25 CI 95% 0.09–0.70, p = 0.008]. A significative positive association was found between greenness and FEF25–75, since children exposed to the 2nd tertile of NDVI reported a significantly decreased FEF25–75 compared to those in the 3rd tertile [B: −2.40; C.I.95%: −0.48–0.01; p = 0.049]. This cross-sectional study provided additional data on still inconsistent literature referring to respiratory health in children and green spaces, attesting a positive effect of greenness in a specific area of Italy. Further research is still needed.
Introduction:
Recent research focused on the interaction between land cover and the development of allergic and respiratory disease has provided conflicting results and the underlying mechanisms are not fully understood. In particular, green space, which confers an overall positive impact on general health, may be significantly contributing to adverse respiratory health outcomes. This study evaluates associations between surrounding residential land cover (green, grey, agricultural and blue space), including type of forest cover (deciduous, coniferous and mixed), and childhood allergic and respiratory diseases.
Methods:
Data from 8063 children, aged 3-14 years, were obtained from nine European population-based studies participating in the HEALS project. Land-cover exposures within a 500 m buffer centred on each child's residential address were computed using data from the Coordination of Information on the Environment (CORINE) program. The associations of allergic and respiratory symptoms (wheeze, asthma, allergic rhinitis and eczema) with land coverage were estimated for each study using logistic regression models, adjusted for sex, age, body mass index, maternal education, parental smoking, and parental history of allergy. Finally, the pooled effects across studies were estimated using meta-analyses.
Results:
In the pooled analyses, a 10% increase in green space coverage was significantly associated with a 5.9%-13.0% increase in the odds of wheezing, asthma, and allergic rhinitis, but not eczema. A trend of an inverse relationship between agricultural space and respiratory symptoms was observed, but did not reach statistical significance. In secondary analyses, children living in areas with surrounding coniferous forests had significantly greater odds of reporting wheezing, asthma and allergic rhinitis.
Conclusion:
Our results provide further evidence that exposure to green space is associated with increased respiratory disease in children. Additionally, our findings suggest that coniferous forests might be associated with wheezing, asthma and allergic rhinitis. Additional studies evaluating both the type of green space and its use in relation to respiratory conditions should be conducted in order to clarify the underlying mechanisms behind associated adverse impacts.
ABSTRACT
Background Urbanisation has been associated with
temporal and geographical differences in asthma
prevalence in low-income and middle-income countries
(lMics). However, little is known of the mechanisms by
which urbanisation and asthma are associated, perhaps
explained by the methodological approaches used to
assess the urbanisation-asthma relationship.
Objective this review evaluated how epidemiological
studies have assessed the relationship between asthma
and urbanisation in lMics, and explored urban/rural
differences in asthma prevalence.
Methods asthma studies comparing urban/rural areas,
comparing cities and examining intraurban variation
were assessed for eligibility. included publications were
evaluated for methodological quality and pooled Or
were calculated to indicate the risk of asthma in urban
over rural areas.
Results Seventy articles were included in our analysis.
Sixty-three compared asthma prevalence between
urban and rural areas, five compared asthma prevalence
between cities and two examined intraurban variation
in asthma prevalence. Urban residence was associated
with a higher prevalence of asthma, regardless of asthma
definition: current-wheeze Or:1.46 (95% ci:1.22 to
1.74), doctor diagnosis Or:1.89 (95% ci:1.47 to 2.41),
wheeze-ever Or:1.44 (95% ci:1.15 to 1.81), selfreported asthma Or:1.77 (95% ci:1.33 to 2.35), asthma
questionnaire Or:1.52 (95% ci:1.06 to 2.16) and
exercise challenge Or:1.96 (95% ci:1.32 to 2.91).
Conclusions Most evidence for the relationship
between urbanisation and asthma in lMics comes
from studies comparing urban and rural areas. these
studies tend to show a greater prevalence of asthma
in urban compared with rural populations. However,
these studies have been unable to identify which
specific characteristics of the urbanisation process
may be responsible. an approach to understand how
different dimensions of urbanisation, using contextual
household and individual indicators, is needed for
a better understanding of how urbanisation affects
asthma.(PrOSPerO registration crD 42017064470).
Green spaces have benefits but may also increase the risk of allergic disease. This study examined the association between the first occurrence of asthma and greenness exposure in children and teenagers. We conducted a 1:1 matched case-control study matched by sex, age, and the first diagnosis year with 7040 eligible subjects from a systematic sampling cohort database in Taiwan from 2001 to 2013. A normalized difference vegetation index (NDVI) value ≥0.4 was used as the criterion to determine the green space. The green cover images were then transformed to the green coverage rate in the township surrounding the residential areas of the asthma and control subjects. Conditional logistic regression analyses demonstrated that a significantly increased risk of asthma in preschool children was associated with the surrounding greenness after adjusting for urbanization level, frequency of healthcare provider visits, mean township family income, CO, NOx, and PM2.5. The risk of asthma occurrence increased significantly with increasing greenness exposure (p-trend < 0.05). Nevertheless, exposure to the highest greenness levels (81–100%) was not associated with a significantly higher risk of asthma occurrence than was exposure to the lowest values (0–20%) of greenness. This study suggests that green space design should consider more effective methods of reducing the allergy impact.
Background
The relationship between smoking, household pollution, dual exposure and severity of asthma in adults has not been sufficiently studied. We examined and compared the effects of cigarette smoking, domestic wood burning pollution and dual exposure (tobacco and wood burning) upon asthma severity in adults.
Methods
This was a cross-sectional study performed with 452 individuals with mild to moderate asthma and 544 patients with severe asthma (previously untreated). Smoking and exposure to wood smoke were identified and quantified through questionnaires to evaluate current and/or previous exposure; objective determination of cigarette exposure was obtained through the measurement of urinary cotinine. Asthma control was evaluated through Asthma Control Questionnaire; and severity was classified according to the Global Initiative for Asthma criteria. Subjects were grouped according to exposure type into 4 groups: smokers, household pollution, dual-exposure and no-exposure. Chi square, Mann–Whitney, and Kruskal–Wallis tests were used for comparisons between groups.
Results
Out of 996 included individuals, 78 (7.8%) were exposed to cigarette smoking alone, 358 (35.9%) to household pollution alone, 155 (15.6%) to the two exposures combined and 405 (40.7%) were not exposed. Compared to unexposed individuals, exposure to household pollution resulted in poorer asthma control, higher proportion of severe asthma, and worse indicators of lung function. The double-exposed individuals were worse off in all the evaluated parameters, and they were significantly worse than subjects with single exposure to household air pollution in relation to asthma severity and lung function. These subjects were predominantly females, older, with longer residence time in rural areas, lower income and lower schooling levels. Multivariate analysis showed that exposure to household pollution and double exposure were predictive factors associated with lack of control and increased severity of asthma.
Conclusions
Exposure to household pollution is associated with poorer control, greater severity, and poorer pulmonary function; double-exposed individuals have a greater risk of severe asthma and decreased lung function than those exposed only to household pollution.
Objective:
To evaluate the prevalence of and risk factors for allergen sensitisation among patients with chronic respiratory disease (CRD) in southern Viet Nam.
Design:
An environmental questionnaire and skin prick tests for airborne and food allergens were administered to patients with CRD, defined as individuals with respiratory symptoms and lung function defects.
Results:
Of 610 CRD patients, 56% had chronic obstructive pulmonary disease and 31% were asthma patients; 80% were males. The most frequent sensitisers were dust mites (Dermatophagoides farinae 22%, Blomia tropicalis 19%, D. pteronyssinus 18%) and cockroach droppings (13%). Among study participants, 37% were from rural settings and 36% from urban areas, whereas 27% had migrated from rural to urban areas. Compared with people from rural areas, being born in an urban area was a risk factor for sensitisation to mites (OR 1.56, 95%CI 1.11-2.20, P < 0.02). In multivariate analysis, place of birth remained a risk factor for mite sensitisation. Compared with the native urban population, the risk of mite sensitisation was not significantly different among patients born in rural areas and those migrating to urban areas.
Conclusion:
Dust mites and cockroach droppings were the most frequent allergens among people with CRD in the south of Viet Nam. Compared with the urban population, being native to a rural area was protective against mite sensitisation, but this effect ceased to be significant after migration from rural to urban areas.
Background and objective:
The relationship between age and asthma phenotypes is important as population is ageing, asthma is becoming common in older ages and recently developed treatments for asthma are guided by phenotypes. The aim of this study is to evaluate whether age is associated with specific asthma phenotypes.
Methods:
This is a cross-sectional study. We included subjects with asthma of varied degrees of severity. Subjects underwent spirometry, skin prick test to aeroallergens, answered the Asthma Control Questionnaire and had blood samples collected. We performed binary logistic regression analysis to evaluate whether age is associated with asthma phenotypes.
Results:
We enrolled 868 subjects. In comparison with subjects ≤ 40 years, older subjects had high odds of irreversible airway obstruction (from 41 to 64 years, OR: 1.83 (95% CI: 1.32-2.54); ≥65 years, OR: 3.45 (2.12-5.60)) and severe asthma phenotypes (from 41 to 64 years, OR: 3.23 (2.26-4.62); ≥65 years, OR: 4.55 (2.39-8.67)). Older subjects had low odds of atopic (from 41 to 64 years, OR: 0.56 (0.39-0.79); ≥65 years, OR: 0.47 (0.27-0.84)) and eosinophilic phenotypes (from 41 to 64 years, OR: 0.63 (0.46-0.84); ≥65 years, OR: 0.39 (0.24-0.64)).
Conclusion:
Older subjects with asthma have low odds of atopic and eosinophilic phenotypes, whereas they present high odds of irreversible airway obstruction and severe asthma.
Background
The association between atopy and asthma is attenuated in non-affluent populations, an effect that may be explained by childhood infections such as geohelminths.Objective
To investigate the association between atopy and wheeze in schoolchildren living in urban and rural areas of Ecuador and examine the effects of geohelminths on this association.Methods
We performed nested case-control studies among comparable populations of schoolchildren living in rural communities and urban neighbourhoods in the Province of Esmeraldas, Ecuador. We detected geohelminths in stool samples, measured recent wheeze and environmental exposures by parental questionnaire, and atopy by specific IgE (sIgE) and skin prick test (SPT) reactivity to aeroallergens.ResultsAtopy, particularly sIgE to house dust mite (HDM), was more strongly associated with recent wheeze in urban than rural schoolchildren: (urban, adj. OR 5.19, 95% CI 3.37-8.00, P<0.0001; rural, adj. OR 1.81, 95%CI 1.09-2.99, P=0.02; interaction, P<0.001). The population fractions of wheeze attributable to atopy were approximately two-fold greater in urban schoolchildren: SPT to any allergen (urban 23.5% vs. rural 10.1%), SPT to HDM (urban 18.5% vs. rural 9.6%), and anti-HDM IgE (urban 26.5% vs. rural 10.5%), while anti-Ascaris IgE was related to wheeze in a high proportion of rural (49.7%) and urban (35.4%) children. The association between atopy and recent wheeze was attenuated by markers of geohelminth infections.Conclusions
Our data suggest that urban residence modifies the association between HDM atopy and recent wheeze, and this effect is explained partly by geohelminth infections.This article is protected by copyright. All rights reserved.
Background: Pollen is a key source of aeroallergens responsible for allergic rhinitis, conjunctivitis, and asthma. Objective: The goal of this scoping review was to summarize current available literature on the factors that affect pollen counts, allergenicity, and thresholds that induce symptoms in individuals who were sensitized. Methods: Several databases showed no published articles with a similar scope as of January 2022. A search of these data bases yielded 373 articles for assessment. These were then reviewed for relevance, and articles were selected to demonstrate the breadth of available data on pollen counts, allergenicity, and thresholds that induce symptoms in individuals who were sensitized. Additional articles were identified through examination of bibliographies of search-identified articles. Results: Several environmental factors have shown a correlation with pollen counts and allergen load, including the distance from the source, wind characteristics, pollen size, terrain, urban environments, air composition (particulate matter, CO₂ levels, ozone, NO₂), and weather conditions (humidity, thunderstorms, precipitation). Pollen thresholds at which symptoms were induced varied by study, pollen type, symptom, disease, and location. In addition, there was heterogeneity in study designs, threshold definition, and outcome measures. Conclusion: This scoping review demonstrates the plethora of variables that influence the relationship between pollen and the symptoms of allergic diseases. Analysis of the available data sheds light on the complex interaction between environmental and biologic factors that affect pollen's role in allergic diseases and provides guidance on multiple areas for further investigation.
Introduction:
Current guidelines incorporate the option of a rapid onset bronchodilator (ROB) plus an inhaled corticosteroid (ICS) for the relief of asthma symptoms, but there is doubt whether the combined therapy for relief could lead to suboptimal maintenance therapy since individuals might prefer it to the maintenance therapy. The objective of this study was to assess whether the type of rescue medication that the individual with asthma has available is associated with suboptimal maintenance therapy.
Methods:
This cross-sectional study included non-smokers with asthma, ≥12 years old. The individuals attended an appointment with a physician, responded questionnaires and performed a spirometry. Adjusted regression analysis evaluated whether the type of rescue medication was associated with suboptimal maintenance therapy.
Results:
We enrolled 953 individuals, of which 221 reported having no rescue medication, 171 carried any ROB + ICS for symptoms relief and 561 carried SABA alone to rescue. The frequency of suboptimal maintenance therapy was not different between individuals carrying the combination and those carrying SABA alone for symptoms relief, but individuals who reported having no rescue medication had less suboptimal maintenance therapy (P < 0.01).
Conclusions:
The frequency of suboptimal maintenance therapy for asthma was similar between individuals carrying any ROB + ICS for symptoms relief and those carrying SABA alone to rescue, whilst it was less frequent in the group that reported not having any reliever medication. Data from this study indicate that recent changes in asthma guidelines regarding the use of rescue medication have little risk of impairing maintenance therapy.
Objective:
to synthesize the Italian epidemiological contribution to knowledge on indoor pollution respiratory impact, and to analyze the perspective of some GARD countries on the health effects of indoor air pollution.
Results:
Italian epidemiological analytical studies confirmed a strong relationship between indoor air pollution and health in general population. Environmental tobacco smoke, biomass (wood/coal) fuel for cooking/heating and indoor allergens (house dust mites, cat and dog dander, mold/damp) are the most relevant indoor pollution sources and are related to respiratory and allergic symptoms/diseases in Italy and in other GARD countries such as Mexico, Brazil, Vietnam, India, Nepal and Kyrgyzstan. Community-based global health collaborations are working to improve prevention, diagnosis and care of respiratory diseases around the world, specially in low- and middle-income countries, through research and education.
Conclusions:
in the last thirty years, the scientific evidence produced on respiratory health effects of indoor air pollution has been extensive, but the necessity to empower the synergies between scientific community and local administrations remains a challenge to address in order to implement effective interventions. Based on abundant evidence of indoor pollution health effect, WHO, scientific societies, patient organizations and other members of the health community should work together to pursue the GARD vision of "a world where all people breathe freely" and encourage policy makers to increase their engagement in advocacy for clean air.
Background: In recent years, an increase of allergies and asthma has been observed throughout the world, more so in Western countries than in less developed ones. Although genetics may play a role in this increase, there are many other factors that may have contributed to the upsurge. Objective: The purpose of the present report was to review the many factors associated with modernization and lifestyle that may have contributed to the allergy and/or asthma epidemic, with a particular focus on those aspects that have particular relevance for the allergist/immunologist. Results: The marked rise in allergy and asthma has been significantly seen in more-developed countries, greater in urban than in rural areas, more pronounced in affluent than in poorer societies, and in individuals who have migrated from developing countries to industrialized countries. A widely accepted explanation for this rise is the “hygiene hypothesis,” which postulates a critical dependence on microbial infection for maintenance of a healthy balanced immune system and that extremely clean external environments, often found in the developed world, can derail equilibrated immune development. With the control of infectious diseases, the immune system shifts from a balanced equilibrated immunologic structure to a more Th2 driven proinflammatory state often associated with IgE and eosinophil-related disorders. Conclusion: Modernization has been associated with increased development of allergies and asthma through a cleaner environment and more exposure to allergens and to multiple other contributory factors. The marked reduction in infectious diseases in recent decades permitted the immune system to switch from fighting infectious disease agents and parasites to reacting adversely (hypersensitivity) to benign environmental agents (allergens) and even to self-antigens (autoimmunity).
Background:
It is unclear if depression is associated with impaired lung function in subjects with asthma, while few studies evaluated the effect of antidepressants on the relationship between depression and asthma. We designed this study to investigate if subjects with concomitant asthma and depression not taking antidepressants have worse asthma outcomes compared to asthmatic subjects without depression, and to evaluate whether antidepressants modify this association.
Methods:
This is a cross-sectional study. We included non-smokers with asthma, 18 years old or above. Study subjects attended an appointment with a chest physician, answered study questionnaires and underwent a spirometry test. We performed crude and adjusted binary logistic regression analyses.
Results:
We enrolled 309 subjects with asthma, of whom 48 with depression taking antidepressants, 52 with depression not taking antidepressants, and 209 without depression (control group). Asthmatic subjects with depression who had not used antidepressants before enrollment were more likely to have uncontrolled symptoms of asthma [adjusted OR 3.10, 95CI (1.56-6.15)] and airway obstruction [adjusted OR 2.41, 95CI (1.24-4.69)] compared to the control group. Subjects who had used antidepressants had higher odds of uncontrolled symptoms of asthma [adjusted OR 3.02, 95CI (1,50-6.07)], but similar odds of airway obstruction [adjusted OR 1.24, 95CI (0.87-1.77)] compared to the control group.
Conclusions:
Non-treated depression is associated with airway obstruction in subjects with asthma, but antidepressants modify this association. Thus, we recommend regular screening of depression in subjects with asthma, and prescription of antidepressants whenever depression symptoms justify pharmacological therapy.
Limitations of Normalized Difference Vegetation Index (NDVI) potentially contributed to the inconsistent findings of greenspace exposure and childhood asthma. The aim of this study was to use a novel greenness exposure assessment method, capable of overcoming the limitation of NDVI to determine the extent to which it was associated with asthma prevalence in Chinese children. During 2009–2013, a cross-sectional study of 59,754 children aged 2–17 years was conducted in northeast China. Tencent street view images surrounding participants’ schools were segmented by a deep learning model, and streetscape greenness was extracted. The green view index (GVI) was used to assign exposure and higher value indicates more green coverage. Mixed-effects logistic regression models were used to calculate the adjusted odds of asthma per interquartile range (IQR) increase of GVI for trees and grass. Participants were further stratified to investigate whether particulate matter with an aerodynamic diameter <2.5 μm (PM2.5) was a modifier. An IQR increase in GVI800m for trees was associated with lower adjusted odds of doctor-diagnosed asthma (OR: 0.76; 95%CI: 0.72–0.80) and current asthma (OR: 0.82; 95%CI: 0.75–0.89). An IQR increase in GVI800m for grass was associated with higher adjusted odds of doctor-diagnosed asthma (OR: 1.04; 95%CI: 1.00–1.08) and current asthma (OR: 1.08; 95%CI: 1.02–1.14). After stratification by PM2.5 exposure level, the negative association between trees and asthma, and the positive association between grass and asthma were observed only in low PM2.5 exposure levels (≤median: 56.23 μg/m³). Our results suggest that types of vegetation may play a role in the association between greenness exposure and childhood asthma. Exposure to trees may reduce the odds of childhood asthma, whereas exposure to grass may increase the odds. Additionally, PM2.5 may modify the associations of trees and grass with childhood asthma.
The low prevalence of asthma and allergies in farm children has partially been ascribed to the consumption of raw cow's milk. A literature search identified twelve publications on eight pertinent studies. A meta-analysis corroborated the protective effect of raw milk consumption early in life (< 1 to 5 years, according to study) on asthma (odds ratio 0.58 [0.49-0.69]), current wheeze (0.66 [0.55-0.78]), hay fever or allergic rhinitis (0.68 [0.57-0.82]), and atopic sensitization [0.76 [0.62-0.95]). The effect particularly on asthma was not only observed in children raised on farms (0.62 [0.58-0.82]), but also in children living in rural areas but not on a farm (0.60 [0.48-0.74]). This demonstrates that the effect of farm milk consumption is independent of other farm exposures and that children not living on a farm can theoretically profit from this effect. Because of the minimal but real risk of life-threatening infections, however, consumption of raw milk and products thereof is strongly discouraged. Raw farm milk and industrially processed milk differ in many instances including removal of cellular components, manipulation of the fat fraction, and various degrees of heating. Preliminary evidence attributes the effect to heat-labile molecules and components residing in the fat fraction. The MARTHA trial (martha-studie.de) is currently testing the protective effect of microbiologically safe, minimally processed cow's milk against standard ultra-heat treated milk in children from 6 months to 3 years with the primary outcome of an asthma diagnosis until age 5 years. If successful, this approach might provide a simple but effective prevention strategy.
Introduction:
It is unknown whether rural-urban migration contributes to worse the burden of asthma in the cities.
Objectives:
The aim of this study was to evaluate whether subjects with asthma that migrated from rural areas to a large urban center in Brazil have more severe disease than asthmatic subjects that was born and always lived in the urban area.
Methods:
This is a case-control study. We enrolled two groups of subjects with asthma currently living in a large urban center in Brazil: 486 subjects with moderate-severe asthma and 432 subjects with mild asthma.
Results:
Rural-urban migrants had higher odds of moderate-severe asthma [adjusted OR 1.57, 95 CI (1.18-2.01)] and uncontrolled symptoms of asthma [adjusted OR 1.80, 95 CI (1.16-2.76)] than urban-born subjects.
Conclusions:
Rural-urban migrants in Brazil have more severe asthma than urban-born subjects. Our results suggest that rural-urban migration is associated with the high burden of asthma in the urban area. This article is protected by copyright. All rights reserved.
Background:
Pollen is an important aeroallergen that triggers asthma exacerbations in children, but we know little about the impact of different pollen types in cities with varying climatic conditions and pollen seasons.
Objectives:
We aimed to assess the role of ambient level of different types of pollen on a large time series of child and adolescent asthma hospitalizations in Sydney, Australia.
Methods:
Childhood asthma hospitalization and the daily ambient pollen concentrations of different species were collected in South-West Sydney. With a bidirectional case-crossover design, we fitted conditional logistic regression models to measure the associations between instantaneous and up to 3 days lagged effects of pollen concentrations on asthma hospitalizations after controlling for potential confounders and testing for interactions.
Results:
A total of 2098 children, more boys (59.7%) and 2-5 years old (62.6%), were hospitalized due to asthma. The geometric mean concentration of Cupressus, 7.88 [5.02] grains/m3 , was the highest during the study period. The increase from 75th to 90th percentile of grass (OR = 1.037, 95% CI 1.005-1.070), weed other than Plantago species (OR = 1.053, 95% CI 1.009-1.098) and unclassified pollen (OR = 1.034, 95% CI 1.010-1.058) were significantly associated with the odds of asthma hospitalizations. Boys were at greater risk of asthma exacerbations associated with grass (OR = 1.046, 95% CI 1.003-1.090) and unclassified pollen (OR = 1.041, 95% CI 1.010-1.073). There was evidence of effect modification by age groups for Cupressus, conifer, total tree and total pollen.
Conclusions:
Although boys are more vulnerable to grass pollen, weed, and other pollen are also important triggers of asthma exacerbations in all children and adolescents. These findings are important for urban green space planning and the development of pollen monitoring systems for families with children at risk of asthma exacerbations during peak pollen seasons.
Introduction:
Previous cross sectional studies could establish an association between prevalence of self reported wheeze and urban-rural environment, but the impact of urbanization on meaningful outcomes of asthma for public health is not established yet.
Objectives:
Evaluate the effect of urbanization on asthma burden.
Methods:
A time series study of 5,505 Brazilian municipalities. The unit of analysis was the municipality. Two time frames were evaluated: from 1999 to 2001 and from 2009 to 2011. Trends from the first to the second time frame were evaluated. Governmental databases were the source of information. Multivariate binary logistic regression models were used.
Results:
In the age range from 5 to 24 years old, municipalities with increase in the proportion of individuals living in urban area had lower odds to reduce hospital admission rate from asthma (OR: 0.93) and lower odds to reduce death rate from asthma (OR: 0.88). In the age range from 25 to 39 years old, municipalities with increase in the proportion of individuals living in urban area had lower odds to reduce hospital admission rate from asthma (OR: 0.93) and lower odds to reduce death rate from asthma (OR: 0.82). Municipalities that increased access to physicians and that supplied inhaled corticosteroids free of charge for asthma since year 2003 had increased odds to reduce hospital admission and death rates from asthma.
Conclusions:
Increase in urban population was associated with lower odds to reduce hospital admission and death rates from asthma in children and young adults living in a transition society. This article is protected by copyright. All rights reserved.
European cross-sectional studies have suggested that prenatal and postnatal farm exposure decreases the risk of allergic diseases in childhood. Underlying immunologic mechanisms are still not understood but might be modulated by immune-regulatory cells early in life, such as regulatory T (Treg) cells.
We sought to assess whether Treg cells from 4.5-year-old children from the Protection against Allergy: Study in Rural Environments birth cohort study are critical in the atopy and asthma-protective effect of farm exposure and which specific exposures might be relevant.
From 1133 children, 298 children were included in this study (149 farm and 149 reference children). Detailed questionnaires until 4 years of age assessed farming exposures over time. Treg cells were characterized as upper 20% CD4(+)CD25(+) forkhead box protein 3 (FOXP3)(+) (intracellular) in PBMCs before and after stimulation (with phorbol 12-myristate 13-acetate/ionomycin or LPS), and FOXP3 demethylation was assessed. Atopic sensitization was defined by specific IgE measurements; asthma was defined by a doctor's diagnosis.
Treg cells were significantly increased in farm-exposed children after phorbol 12-myristate 13-acetate/ionomycin and LPS stimulation. Exposure to farm milk was defined as a relevant independent farm-related exposure supported by higher FOXP3 demethylation. Treg cell (upper 20% CD4(+)CD25(+), FOXP3(+) T cells) numbers were significantly negatively associated with doctor-diagnosed asthma (LPS stimulated: adjusted odds ratio, 0.26; 95% CI, 0.08-0.88) and perennial IgE (unstimulated: adjusted odds ratio, 0.21; 95% CI, 0.08-0.59). Protection against asthma by farm milk exposure was partially mediated by Treg cells.
Farm milk exposure was associated with increased Treg cell numbers on stimulation in 4.5-year-old children and might induce a regulatory phenotype early in life, potentially contributing to a protective effect for the development of childhood allergic diseases.
Within the context of the hygiene hypothesis, we aimed to study the potential association between farming-related risk factors and Toxoplasma gondii (T. gondii) as well as Helicobacter pylori (H. pylori) seropositivity.
The study included questionnaire data and serum samples of 321 young adults living in a rural environment. Serum samples were analysed for specific IgE to a common panel of aeroallergens (SX1) as well as IgG against T. gondii and H. pylori.
Regular contact with animal stables before the age of 3 years (odds ratio (OR) (95% confidence interval): 2.0 [1.0; 4.0]) and unpasteurized milk consumption at age 6 years (1.8 [1.0; 3.3]) were the strongest risk factors for T. gondii infection. None of the farming-related factors were significantly associated with H. pylori infection. Current consumption of raw farm milk was not significantly associated with H. pylori infection (2.1 [0.8; 5.3]). Regular contact with animal houses before the age of 7 years was the strongest predictor for atopy (0.49 [0.26-0.96]). The reduction in risk could not be further decreased by any other factor under consideration. After adjustment for animal house contact, the OR for atopy was decreased by raw milk consumption and H. pylori infection in an additive manner.
Exposure to farming environments in childhood might predict T. gondii seropositivity in rural subjects. Nevertheless, the strongest predictor for atopy in rural subjects seems to be regular contact with farm animals. Whether T. gondii infection is an intermediate factor in the association between farm contact and atopy needs to be confirmed in larger studies.
Effect of urbanisation on the relationship between total serum IgE and asthma
- Checkley
Effect of air pollution on asthma
- Zhou