Integration of gene expression and DNA methylation identifies epigenetically controlled modules related to PM2.5 exposure

Air pollution has been associated with adverse health effects across the life-course. Although underlying mechanisms are unclear, several studies suggested pollutant-induced changes in transcriptomic profiles. In this meta-analysis of transcriptome-wide association studies of 656 children and adolescents from three European cohorts participating in the MeDALL Consortium, we found two differentially expressed transcript clusters (FDR p < 0.05) associated with exposure to particulate matter < 2.5 µm in diameter (PM_2.5) at birth, one of them mapping to the MIR1296 gene. Further, by integrating gene expression with DNA methylation using Functional Epigenetic Modules algorithms, we identified 9 and 6 modules in relation to PM_2.5 exposure at birth and at current address, respectively (including NR1I2, MAPK6, TAF8 and SCARA3). In conclusion, PM_2.5 exposure at birth was linked to differential gene expression in children and adolescents. Importantly, we identified several significant interactome hotspots of gene modules of relevance for complex diseases in relation to PM_2.5 exposure.

Environmental and nutritional impacts of dietary changes in Spain during the COVID-19 lockdown

The COVID lockdown has affected food purchases and eating habits. In this regard, this short communication assesses the nutritional and environmental impacts of these changes during the COVID lockdown in Spain, by applying Life Cycle Assessment and an energy- and nutrient-corrected functional unit. Three environmental impacts were studied (Global Warming Potential, Blue Water Footprint and Land Use) and a total of seven weekly diet scenarios were designed: two pre-COVID diets for March and April in 2019 (MAR19, APR19), one COVID diet (COVID) and two alternative diets, one based on the National Dietary Guidelines (NDG) and another one on the Planetary Health Diet (PHD). Results show that the COVID diet had larger energy intake and lower nutritional quality, as well as higher environmental impacts (between 30 and 36%) than the pre-COVID eating patterns. Further research is needed to account for food affordability within this assessment, as well as to analyze how eating patterns will evolve after the COVID lockdown. Finally, the definition of short guidelines for sustainable food behaviors for future possible lockdowns is suggested, as well as the introduction of sustainable indicators within NDGs.

A novel whole blood gene expression signature for asthma, dermatitis, and rhinitis multimorbidity in children and adolescents

BACKGROUND

Allergic diseases often occur in combination (multimorbidity). Human blood transcriptome studies have not addressed multimorbidity. Large-scale gene expression data were combined to retrieve biomarkers and signaling pathways to disentangle allergic multimorbidity phenotypes.

METHODS

Integrated transcriptomic analysis was conducted in 1233 participants with a discovery phase using gene expression data (Human Transcriptome Array 2.0) from whole blood of 786 children from three European birth cohorts (MeDALL), and a replication phase using RNA Sequencing data from an independent cohort (EVA-PR, n = 447). Allergic diseases (asthma, atopic dermatitis, rhinitis) were considered as single disease or multimorbidity (at least two diseases), and compared with no disease.

RESULTS

Fifty genes were differentially expressed in allergic diseases. Thirty-two were not previously described in allergy. Eight genes were consistently overexpressed in all types of multimorbidity for asthma, dermatitis, and rhinitis (CLC, EMR4P, IL5RA, FRRS1, HRH4, SLC29A1, SIGLEC8, IL1RL1). All genes were replicated the in EVA-PR cohort. RT-qPCR validated the overexpression of selected genes. In MeDALL, 27 genes were differentially expressed in rhinitis alone, but none was significant for asthma or dermatitis alone. The multimorbidity signature was enriched in eosinophil-associated immune response and signal transduction. Protein-protein interaction network analysis identified IL5/JAK/STAT and IL33/ST2/IRAK/TRAF as key signaling pathways in multimorbid diseases. Synergistic effect of multimorbidity on gene expression levels was found.

CONCLUSION

A signature of eight genes identifies multimorbidity for asthma, rhinitis, and dermatitis. Our results have clinical and mechanistic implications, and suggest that multimorbidity should be considered differently than allergic diseases occurring alone.

Air pollution and IgE sensitization in 4 European birth cohorts-the MeDALL project

BACKGROUND

Whether long-term exposure air to pollution has effects on allergic sensitization is controversial.

OBJECTIVE

Our aim was to investigate associations of air pollution exposure at birth and at the time of later biosampling with IgE sensitization against common food and inhalant allergens, or specific allergen molecules, in children aged up to 16 years.

METHODS

A total of 6163 children from 4 European birth cohorts participating in the Mechanisms of the Development of ALLergy [MeDALL] consortium were included in this meta-analysis of the following studies: Children, Allergy, Milieu, Stockholm, Epidemiology (BAMSE) (Sweden), Influences of Lifestyle-Related Factors on the Human Immune System and Development of Allergies in Childhood (LISA)/German Infant Study on the Influence of Nutrition Intervention PLUS Environmental and Genetic Influences on Allergy Development (GINIplus) (Germany), and Prevention and Incidence of Asthma and Mite Allergy (PIAMA) (The Netherlands). The following indicators were modeled by land use regression: individual residential outdoor levels of particulate matter with aerodynamic diameters less than 2.5 μm, less than 10 μm, and between 2.5 and 10 μm; PM_2.5 absorbance (a measurement of the blackness of PM_2.5 filters); and nitrogen oxides levels. Blood samples drawn at ages 4 to 6 (n = 5989), 8 to 10 (n = 6603), and 15 to 16 (n = 5825) years were analyzed for IgE sensitization to allergen extracts by ImmunoCAP. Additionally, IgE against 132 allergen molecules was measured by using the MedALL microarray chip (n = 1021).

RESULTS

Air pollution was not consistently associated with IgE sensitization to any common allergen extract up to age 16 years. However, allergen-specific analyses suggested increased risks of sensitization to birch (odds ratio [OR] = 1.12 [95% CI = 1.01-1.25] per 10-μg/m³ increase in NO₂ exposure). In a subpopulation with microarray data, IgE to the major timothy grass allergen Phleum pratense 1 (Phl p 1) and the cat allergen Felis domesticus 1 (Fel d 1) greater than 3.5 Immuno Solid-phase Allergen Chip standardized units for detection of IgE antibodies were related to PM_2.5 exposure at birth (OR = 3.33 [95% CI = 1.40-7.94] and OR = 4.98 [95% CI = 1.59-15.60], respectively, per 5-μg/m³ increase in exposure).

CONCLUSION

Air pollution exposure does not seem to increase the overall risk of allergic sensitization; however, sensitization to birch as well as grass pollen Phl p 1 and cat Fel d 1 allergen molecules may be related to specific pollutants.

Epigenome-wide meta-analysis of blood DNA methylation in newborns and children identifies numerous loci related to gestational age

BACKGROUND

Preterm birth and shorter duration of pregnancy are associated with increased morbidity in neonatal and later life. As the epigenome is known to have an important role during fetal development, we investigated associations between gestational age and blood DNA methylation in children.

METHODS

We performed meta-analysis of Illumina's HumanMethylation450-array associations between gestational age and cord blood DNA methylation in 3648 newborns from 17 cohorts without common pregnancy complications, induced delivery or caesarean section. We also explored associations of gestational age with DNA methylation measured at 4-18 years in additional pediatric cohorts. Follow-up analyses of DNA methylation and gene expression correlations were performed in cord blood. DNA methylation profiles were also explored in tissues relevant for gestational age health effects: fetal brain and lung.

RESULTS

We identified 8899 CpGs in cord blood that were associated with gestational age (range 27-42 weeks), at Bonferroni significance, P < 1.06 × 10- 7, of which 3343 were novel. These were annotated to 4966 genes. After restricting findings to at least three significant adjacent CpGs, we identified 1276 CpGs annotated to 325 genes. Results were generally consistent when analyses were restricted to term births. Cord blood findings tended not to persist into childhood and adolescence. Pathway analyses identified enrichment for biological processes critical to embryonic development. Follow-up of identified genes showed correlations between gestational age and DNA methylation levels in fetal brain and lung tissue, as well as correlation with expression levels.

CONCLUSIONS

We identified numerous CpGs differentially methylated in relation to gestational age at birth that appear to reflect fetal developmental processes across tissues. These findings may contribute to understanding mechanisms linking gestational age to health effects.

Prenatal Particulate Air Pollution and DNA Methylation in Newborns: An Epigenome-Wide Meta-Analysis

BACKGROUND

Prenatal exposure to air pollution has been associated with childhood respiratory disease and other adverse outcomes. Epigenetics is a suggested link between exposures and health outcomes.

OBJECTIVES

We aimed to investigate associations between prenatal exposure to particulate matter (PM) with diameter [Formula: see text] ([Formula: see text]) or [Formula: see text] ([Formula: see text]) and DNA methylation in newborns and children.

METHODS

We meta-analyzed associations between exposure to [Formula: see text] ([Formula: see text]) and [Formula: see text] ([Formula: see text]) at maternal home addresses during pregnancy and newborn DNA methylation assessed by Illumina Infinium HumanMethylation450K BeadChip in nine European and American studies, with replication in 688 independent newborns and look-up analyses in 2,118 older children. We used two approaches, one focusing on single cytosine-phosphate-guanine (CpG) sites and another on differentially methylated regions (DMRs). We also related PM exposures to blood mRNA expression.

RESULTS

Six CpGs were significantly associated [false discovery rate (FDR) [Formula: see text]] with prenatal [Formula: see text] and 14 with [Formula: see text] exposure. Two of the [Formula: see text] CpGs mapped to FAM13A (cg00905156) and NOTCH4 (cg06849931) previously associated with lung function and asthma. Although these associations did not replicate in the smaller newborn sample, both CpGs were significant ([Formula: see text]) in 7- to 9-y-olds. For cg06849931, however, the direction of the association was inconsistent. Concurrent [Formula: see text] exposure was associated with a significantly higher NOTCH4 expression at age 16 y. We also identified several DMRs associated with either prenatal [Formula: see text] and or [Formula: see text] exposure, of which two [Formula: see text] DMRs, including H19 and MARCH11, replicated in newborns.

CONCLUSIONS

Several differentially methylated CpGs and DMRs associated with prenatal PM exposure were identified in newborns, with annotation to genes previously implicated in lung-related outcomes. https://doi.org/10.1289/EHP4522.

Occupational exposures and incidence of chronic bronchitis and related symptoms over two decades: the European Community Respiratory Health Survey

OBJECTIVES

Chronic bronchitis (CB) is an important chronic obstructive pulmonary disease (COPD)-related phenotype, with distinct clinical features and prognostic implications. Occupational exposures have been previously associated with increased risk of CB but few studies have examined this association prospectively using objective exposure assessment. We examined the effect of occupational exposures on CB incidence in the European Community Respiratory Health Survey.

METHODS

Population samples aged 20-44 were randomly selected in 1991-1993, and followed up twice over 20 years. Participants without chronic cough or phlegm at baseline were analysed. Coded job histories during follow-up were linked to the ALOHA Job Exposure Matrix, generating occupational exposure estimates to 12 categories of chemical agents. Their association with CB incidence over both follow-ups was examined with Poisson models using generalised estimating equations.

RESULTS

8794 participants fulfilled the inclusion criteria, contributing 13 185 observations. Only participants exposed to metals had a higher incidence of CB (relative risk (RR) 1.70, 95% CI 1.16 to 2.50) compared with non-exposed to metals. Mineral dust exposure increased the incidence of chronic phlegm (RR 1.72, 95% CI 1.43 to 2.06). Incidence of chronic phlegm was increased in men exposed to gases/fumes and to solvents and in women exposed to pesticides.

CONCLUSIONS

Occupational exposures are associated with chronic phlegm and CB, and the evidence is strongest for metals and mineral dust exposure. The observed differences between men and women warrant further investigation.

Green and blue spaces and physical functioning in older adults: Longitudinal analyses of the Whitehall II study

There is increasing evidence of the health benefits of exposure to natural environments, including green and blue spaces. The association with physical functioning and its decline at older age remains to be explored. The aim of the present study was to investigate the longitudinal association between the natural environment and the decline in physical functioning in older adults. We based our analyses on three follow-ups (2002-2013) of the Whitehall II study, including 5759 participants (aged 50 to 74 years at baseline) in the UK. Exposure to natural environments was assessed at each follow-up as (1) residential surrounding greenness across buffers of 500 and 1000 m around the participants' address using satellite-based indices of greenness (Enhanced Vegetation Index (EVI) and Normalized Difference Vegetation Index (NDVI)) and (2) the distance from home to the nearest natural environment, separately for green and blue spaces, using a land cover map. Physical functioning was characterized by walking speed, measured three times, and grip strength, measured twice. Linear mixed effects models were used to quantify the impact of green and blue space on physical functioning trajectories, controlled for relevant covariates. We found higher residential surrounding greenness (EVI and NDVI) to be associated with slower 10-year decline in walking speed. Furthermore, proximity to natural environments (green and blue spaces combined) was associated with slower decline in walking speed and grip strength. We observed stronger associations between distance to natural environments and decline in physical functioning in areas with higher compared to lower area-level deprivation. However, no association was observed with distance to green or blue spaces separately. The associations with decline in physical functioning were partially mediated by social functioning and mental health. Our results suggest that higher residential surrounding greenness and living closer to natural environments contribute to better physical functioning at older ages.

Residential air pollution does not modify the positive association between physical activity and lung function in current smokers in the ECRHS study

BACKGROUND

Very few studies have examined whether a long-term beneficial effect of physical activity on lung function can be influenced by living in polluted urban areas.

OBJECTIVE

We assessed whether annual average residential concentrations of nitrogen dioxide (NO₂) and particulate matter with aerodynamic diameters < 2.5 μm (PM_2.5) and <10 μm (PM₁₀) modify the effect of physical activity on lung function among never- (N = 2801) and current (N = 1719) smokers in the multi-center European Community Respiratory Health Survey.

METHODS

Associations between repeated assessments (at 27-57 and 39-67 years) of being physically active (physical activity: ≥2 times and ≥1 h per week) and forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) were evaluated using adjusted mixed linear regression models. Models were conducted separately for never- and current smokers and stratified by residential long-term NO₂, PM_2.5 mass and PM₁₀ mass concentrations (≤75th percentile (low/medium) versus >75th percentile (high)).

RESULTS

Among current smokers, physical activity and lung function were positively associated regardless of air pollution levels. Among never-smokers, physical activity was associated with lung function in areas with low/medium NO₂, PM_2.5 mass and PM₁₀ mass concentrations (e.g. mean difference in FVC between active and non-active subjects was 43.0 mL (13.6, 72.5), 49.5 mL (20.1, 78.8) and 49.7 mL (18.6, 80.7), respectively), but these associations were attenuated in high air pollution areas. Only the interaction term of physical activity and PM₁₀ mass for FEV₁ among never-smokers was significant (p-value = 0.03).

CONCLUSIONS

Physical activity has beneficial effects on adult lung function in current smokers, irrespective of residential air pollution levels in Western Europe. Trends among never-smokers living in high air pollution areas are less clear.

Residential Surrounding Greenness and Cognitive Decline: A 10-Year Follow-up of the Whitehall II Cohort

BACKGROUND

Evidence on beneficial associations of green space with cognitive function in older adults is very scarce and mainly limited to cross-sectional studies.

OBJECTIVES

We aimed to investigate the association between long-term residential surrounding greenness and cognitive decline.

METHODS

This longitudinal study was based on three waves of data from the Whitehall II cohort, providing a 10-y follow-up (1997-1999 to 2007-2009) of 6,506 participants (45-68 y old) from the United Kingdom. Residential surrounding greenness was obtained across buffers of 500 and around the participants' residential addresses at each follow-up using satellite images on greenness (Normalized Difference Vegetation Index; NDVI) from a summer month in every follow-up period. Cognitive tests assessed reasoning, short-term memory, and verbal fluency. The cognitive scores were standardized and summarized in a global cognition z-score. To quantify the impact of greenness on repeated measurements of cognition, linear mixed effect models were developed that included an interaction between age and the indicator of greenness, and controlled for covariates including individual and neighborhood indicators of socioeconomic status (SES).

RESULTS

In a fully adjusted model, an interquartile range (IQR) increase in NDVI was associated with a difference in the global cognition z-score of 0.020 [95% confidence interval (CI): 0.003, 0.037; p=0.02] in the 500-m buffer and of 0.021 (95% CI: 0.003, 0.039; p=0.02) in the 1,000-m buffer over 10 y. The associations with cognitive decline over the study period were stronger among women than among men.

CONCLUSIONS

Higher residential surrounding greenness was associated with slower cognitive decline over a 10-y follow-up period in the Whitehall II cohort of civil servants. https://doi.org/10.1289/EHP2875.

Genetic regulation of IL1RL1 methylation and IL1RL1-a protein levels in asthma

Interleukin-1 receptor-like 1 (IL1RL1) is an important asthma gene. (Epi)genetic regulation of IL1RL1 protein expression has not been established. We assessed the association between IL1RL1 single nucleotide polymorphisms (SNPs), IL1RL1 methylation and serum IL1RL1-a protein levels, and aimed to identify causal pathways in asthma.Associations of IL1RL1 SNPs with asthma were determined in the Dutch Asthma Genome-wide Association Study cohort and three European birth cohorts, BAMSE (Children/Barn, Allergy, Milieu, Stockholm, an Epidemiological survey), INMA (Infancia y Medio Ambiente) and PIAMA (Prevention and Incidence of Asthma and Mite Allergy), participating in the Mechanisms of the Development of Allergy study. We performed blood DNA IL1RL1 methylation quantitative trait locus (QTL) analysis (n=496) and (epi)genome-wide protein QTL analysis on serum IL1RL1-a levels (n=1462). We investigated the association of IL1RL1 CpG methylation with asthma (n=632) and IL1RL1-a levels (n=548), with subsequent causal inference testing. Finally, we determined the association of IL1RL1-a levels with asthma and its clinical characteristics (n=1101).IL1RL1 asthma-risk SNPs strongly associated with IL1RL1 methylation (rs1420101; p=3.7×10^-16) and serum IL1RL1-a levels (p=2.8×10^-56). IL1RL1 methylation was not associated with asthma or IL1RL1-a levels. IL1RL1-a levels negatively correlated with blood eosinophil counts, whereas there was no association between IL1RL1-a levels and asthma.In conclusion, asthma-associated IL1RL1 SNPs strongly regulate IL1RL1 methylation and serum IL1RL1-a levels, yet neither these IL1RL1-methylation CpG sites nor IL1RL1-a levels are associated with asthma.

Is there a sex-shift in prevalence of allergic rhinitis and comorbid asthma from childhood to adulthood? A meta-analysis

Background

Allergic rhinitis and asthma as single entities affect more boys than girls in childhood but more females in adulthood. However, it is unclear if this prevalence sex-shift also occurs in allergic rhinitis and concurrent asthma. Thus, our aim was to compare sex-specific differences in the prevalence of coexisting allergic rhinitis and asthma in childhood, adolescence and adulthood.

Methods

Post-hoc analysis of systematic review with meta-analysis concerning sex-specific prevalence of allergic rhinitis. Using random-effects meta-analysis, we assessed male–female ratios for coexisting allergic rhinitis and asthma in children (0–10 years), adolescents (11–17) and adults (> 17). Electronic searches were performed using MEDLINE and EMBASE for the time period 2000–2014. We included population-based observational studies, reporting coexisting allergic rhinitis and asthma as outcome stratified by sex. We excluded non-original or non-population-based studies, studies with only male or female participants or selective patient collectives.

Results

From a total of 6539 citations, 10 studies with a total of 93,483 participants met the inclusion criteria. The male–female ratios (95% CI) for coexisting allergic rhinitis and asthma were 1.65 (1.52; 1.78) in children (N = 6 studies), 0.61 (0.51; 0.72) in adolescents (N = 2) and 1.03 (0.79; 1.35) in adults (N = 2). Male–female ratios for allergic rhinitis only were 1.25 (1.19; 1.32, N = 5) in children, 0.80 (0.71; 0.89, N = 2) in adolescents and 0.98 (0.74; 1.30, N = 2) in adults, respectively.

Conclusions

The prevalence of coexisting allergic rhinitis and asthma shows a clear male predominance in childhood and seems to switch to a female predominance in adolescents. This switch was less pronounced for allergic rhinitis only.

Electronic supplementary material

The online version of this article (10.1186/s13601-017-0176-5) contains supplementary material, which is available to authorized users.

The emerging landscape of dynamic DNA methylation in early childhood

BACKGROUND

DNA methylation has been found to associate with disease, aging and environmental exposure, but it is unknown how genome, environment and disease influence DNA methylation dynamics in childhood.

RESULTS

By analysing 538 paired DNA blood samples from children at birth and at 4-5 years old and 726 paired samples from children at 4 and 8 years old from four European birth cohorts using the Illumina Infinium Human Methylation 450 k chip, we have identified 14,150 consistent age-differential methylation sites (a-DMSs) at epigenome-wide significance of p < 1.14 × 10^-7. Genes with an increase in age-differential methylation were enriched in pathways related to 'development', and were more often located in bivalent transcription start site (TSS) regions, which can silence or activate expression of developmental genes. Genes with a decrease in age-differential methylation were involved in cell signalling, and enriched on H3K27ac, which can predict developmental state. Maternal smoking tended to decrease methylation levels at the identified da-DMSs. We also found 101 a-DMSs (0.71%) that were regulated by genetic variants using cis-differential Methylation Quantitative Trait Locus (cis-dMeQTL) mapping. Moreover, a-DMS-associated genes during early development were significantly more likely to be linked with disease.

CONCLUSION

Our study provides new insights into the dynamic epigenetic landscape of the first 8 years of life.

Personalized respiratory medicine: exploring the horizon, addressing the issues. Summary of a BRN-AJRCCM workshop held in Barcelona on June 12, 2014

This Pulmonary Perspective summarizes the content and main conclusions of an international workshop on personalized respiratory medicine coorganized by the Barcelona Respiratory Network ( www.brn.cat ) and the AJRCCM in June 2014. It discusses (1) its definition and historical, social, legal, and ethical aspects; (2) the view from different disciplines, including basic science, epidemiology, bioinformatics, and network/systems medicine; (3) the bottlenecks and opportunities identified by some currently ongoing projects; and (4) the implications for the individual, the healthcare system and the pharmaceutical industry. The authors hope that, although it is not a systematic review on the subject, this document can be a useful reference for researchers, clinicians, healthcare managers, policy-makers, and industry parties interested in personalized respiratory medicine.

A systematic review of socioeconomic position in relation to asthma and allergic diseases

The role of socioeconomic position (SEP) in the development of asthma and allergies is unclear, with some pointing to the risks of low SEP and other research pointing in the direction of higher SEP being associated with higher prevalence rates. The aim of this systematic review is to clarify associations between SEP and the prevalence of asthma and allergies. Out of 4407 records identified, 183 were included in the analysis. Low SEP was associated with a higher prevalence of asthma in 63% of the studies. Research on allergies, however, showed a positive association between higher SEP and illness in 66% of studies. Pooled estimates for the odds ratio of disease for the highest compared with the lowest SEP confirmed these results for asthma (unadjusted OR 1.38, 95% CI 1.37-1.39), allergies in general (OR 0.67, 95% CI 0.62-0.72), atopic dermatitis (unadjusted OR 0.72, 95% CI 0.61-0.83) and allergic rhinoconjunctivitis (unadjusted OR 0.52, 95% CI 0.46-0.59). Sensitivity analyses with a subsample of high-quality studies led to the same conclusion. Evidence from this systematic review suggests that asthma is associated with lower SEP, whereas the prevalence of allergies is associated with higher SEP.

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.

Positive health effects of the natural outdoor environment in typical populations in different regions in Europe (PHENOTYPE): a study programme protocol

INTRODUCTION

Growing evidence suggests that close contact with nature brings benefits to human health and well-being, but the proposed mechanisms are still not well understood and the associations with health remain uncertain. The Positive Health Effects of the Natural Outdoor environment in Typical Populations in different regions in Europe (PHENOTYPE) project investigates the interconnections between natural outdoor environments and better human health and well-being.

AIMS AND METHODS

The PHENOTYPE project explores the proposed underlying mechanisms at work (stress reduction/restorative function, physical activity, social interaction, exposure to environmental hazards) and examines the associations with health outcomes for different population groups. It implements conventional and new innovative high-tech methods to characterise the natural environment in terms of quality and quantity. Preventive as well as therapeutic effects of contact with the natural environment are being covered. PHENOTYPE further addresses implications for land-use planning and green space management. The main innovative part of the study is the evaluation of possible short-term and long-term associations of green space and health and the possible underlying mechanisms in four different countries (each with quite a different type of green space and a different use), using the same methodology, in one research programme. This type of holistic approach has not been undertaken before. Furthermore there are technological innovations such as the use of remote sensing and smartphones in the assessment of green space.

CONCLUSIONS

The project will produce a more robust evidence base on links between exposure to natural outdoor environment and human health and well-being, in addition to a better integration of human health needs into land-use planning and green space management in rural as well as urban areas.

Advances in allergen-microarray technology for diagnosis and monitoring of allergy: the MeDALL allergen-chip

Allergy diagnosis based on purified allergen molecules provides detailed information regarding the individual sensitization profile of allergic patients, allows monitoring of the development of allergic disease and of the effect of therapies on the immune response to individual allergen molecules. Allergen microarrays contain a large variety of allergen molecules and thus allow the simultaneous detection of allergic patients' antibody reactivity profiles towards each of the allergen molecules with only minute amounts of serum. In this article we summarize recent progress in the field of allergen microarray technology and introduce the MeDALL allergen-chip which has been developed for the specific and sensitive monitoring of IgE and IgG reactivity profiles towards more than 170 allergen molecules in sera collected in European birth cohorts. MeDALL is a European research program in which allergen microarray technology is used for the monitoring of the development of allergic disease in childhood, to draw a geographic map of the recognition of clinically relevant allergens in different populations and to establish reactivity profiles which are associated with and predict certain disease manifestations. We describe technical advances of the MeDALL allergen-chip regarding specificity, sensitivity and its ability to deliver test results which are close to in vivo reactivity. In addition, the usefulness and numerous advantages of allergen microarrays for allergy research, refined allergy diagnosis, monitoring of disease, of the effects of therapies, for improving the prescription of specific immunotherapy and for prevention are discussed.

Evaluation of the persistence of functional and biological respiratory health effects in clean-up workers 6 years after the prestige oil spill

Fishermen who had participated in clean-up activities of the Prestige oil spill showed increased bronchial responsiveness and higher levels of respiratory biomarkers 2 years later. We aimed to evaluate the persistence of these functional and biological respiratory health effects 6 years after clean-up work. In 2008/2009 a follow-up study was done in 230 never-smoking fishermen who had been exposed to clean-up work in 2002/2003 and 87 non-exposed fishermen. Lung function and bronchial responsiveness testing and the determination of respiratory biomarkers in exhaled breath condensate were done identically as in the baseline survey in 2004/2005. Associations between participation in clean-up work and respiratory health parameters were assessed using linear and logistic regression analyses adjusting for sex and age. Information from 158 exposed (69%) and 57 non-exposed (66%) fishermen was obtained. Loss to follow-up in the non-exposed was characterised by less respiratory symptoms at baseline. During the 4-year follow-up period lung function, bronchial hyperresponsiveness and the levels of respiratory biomarkers of oxidative stress and growth factors had deteriorated notably more among non-exposed than among exposed. At follow-up, respiratory health indices were similar or better in clean-up workers than in non-exposed. No clear differences between highly exposed and moderately exposed clean-up workers were found. In conclusion, we could not detect long-term respiratory health effects in clean-up workers 6 years after the Prestige oil spill. Methodological issues that need to be considered in this type of studies include the choice of a non-exposed control group and limitation of follow-up to subgroups such as never smokers.

HLA distribution in COPD patients

BACKGROUND

Auto-immunity may contribute to the pathogenesis of chronic obstructive pulmonary disease (COPD), particularly to the presence of emphysema. Auto-immune diseases are characterized by an abnormal distribution of HLA class II alleles (DR and DQ). The distribution of DRB1 and DQB1 alleles has not been investigated in COPD.

METHODS

To this end, HLA medium-low resolution typing was performed following standardized protocols in 320 clinically stable COPD patients included in the PAC-COPD study. Results were compared with controls of the same geographical and ethnic origin, and potential relationships with the severity of airflow limitation and lung diffusing capacity impairment were explored in patients with COPD.

RESULTS

The distribution of DRB1 and DQB1 alleles in COPD was similar to that of controls except for a significantly higher prevalence of DRB1*14 in patients with severe airflow limitation and low diffusing capacity.

CONCLUSIONS

By and large, HLA distribution was similar in COPD patients and controls, but the HLA class II allele DRB1*14 may contribute to the pathogenesis of severe COPD with emphysema.

Occupational risk factors for hand dermatitis among professional cleaners in Spain

BACKGROUND

Dermatitis is an important health outcome for workers whose jobs put them in contact with irritants or sensitizing agents.

OBJECTIVES

We conducted an analysis of data from the Epidemiological Study on the Risk of Asthma in Cleaning Workers 2 (EPIASLI2) to assess worksites and cleaning products as risk factors for hand dermatitis among professional cleaning workers.

MATERIALS/METHODS

We distributed 4993 questionnaires to employees of 37 cleaning companies, and used data from 818 (16%) respondents who provided information about skin symptoms and cleaning-related exposures. We assessed associations between the frequencies of worksite and cleaning product exposures and a symptom-based definition of hand dermatitis among current cleaning workers (n = 693) and a comparison population (n = 125).

RESULTS

Hand dermatitis was reported by 28% of current cleaning workers, versus 18% of the comparison population, and was associated with cleaning outdoor areas and schools, and the use of hydrochloric acid [prevalence ratio (PR) 1.92, 95% confidence interval (CI) 1.22-3.02] and dust mop products (PR 1.75, 95% CI 1.11-2.75).

CONCLUSIONS

Professional cleaning workers may not be sufficiently protected from cutaneous disease at work. Future research should further investigate the roles of multiple product exposures and personal protective equipment.

Anti-tissue antibodies are related to lung function in chronic obstructive pulmonary disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) is a multicomponent disease. Autoimmunity can contribute to the pathogenesis of COPD.

OBJECTIVES

This study investigates the prevalence of circulating antinuclear antibodies (ANA) and anti-tissue (AT) antibodies, two common markers of autoimmunity, in COPD and their relationship with several components of the disease.

METHODS

We determined lung function, the serum titers of ANA and AT by immunofluorescence, and the serum levels of C-reactive protein (CRP) by high sensitivity nephelometry in 328 patients with clinically stable COPD and in 67 healthy controls recruited in the PAC-COPD study. Multiple linear and logistic regression analysis was used to analyze results.

MEASUREMENTS AND MAIN RESULTS

The prevalence of abnormal ANA and AT titers was 34% and 26% in patients and 3% and 6% in controls, respectively. Levels of AT greater than or equal to 1:320 were seen in 21% of patients with COPD and were independently associated with the severity of airflow limitation and gas transfer impairment (P < 0.05). Neither ANA or AT titers was related to body mass index, current smoking status, use of inhaled steroids, the Charlson index, or serum C-reactive protein values.

CONCLUSIONS

Between a quarter and a third of patients with clinically stable COPD present abnormal titers of circulating ANA and AT. The observed relationship between AT and lung function supports a role for autoimmunity in the pathogenesis of COPD.

Early life environment, neurodevelopment and the interrelation with atopy

Both neurological and immunological systems are vulnerable to early life exposures. Neurological disorders and atopy have been related in animals and humans. Our main objective was to assess whether multiple exposures to early life determinants remain associated with neurodevelopment after considering the potential intermediate role of atopy. A second objective was to assess whether genes associated with atopy may inform about the potential neurotoxical mechanisms. Children were members of the AMICS birth cohort in Menorca (n=418, 87% of the recruited). General cognition was measured with the McCarthy Scales at age 4 and atopy through specific IgE at age 4 and prick test at age 6; 85 single nucleotide polymorphisms (SNPs) in 16 atopy and detoxification genes were genotyped. Among the 27 risk factors assessed, lower maternal social class, maternal smoking during pregnancy, being first born, shorter breastfeeding, higher DDT levels in cord blood, and higher indoor levels of NO2 (among the non-detoxifiers by GSTP1 polymorphism) were independently associated with poorer cognition. These associations were apparently not mediated by the relation between atopy and general cognition. Among the candidate atopic genes, variants in NQ01 (a detoxification gene) and NPRS1 (related with affective disorders like anxiety and stress management) had a significant association with general cognition (p-value<0.001). However, adjustment for the corresponding SNPs did not change the association between the early life determinants and general cognition. Multiple environmental pre-natal exposures were associated with neurodevelopment independently of their role in the immunological system. Atopic genes related to neurodevelopment suggest some potential mechanisms.

Risk factors of new-onset asthma in adults: a population-based international cohort study

BACKGROUND

The occurrence of new-onset asthma during adulthood is common, but there is insufficient understanding of its determinants including the role of atopy.

OBJECTIVE

To assess the risk factors for the development of new-onset asthma in middle-aged adults and to compare them according to atopy.

METHODS

A longitudinal analysis of 9175 young adults who participated in two surveys of the European Community Respiratory Health Survey (ECRHS) conducted 9 years apart.

FINDINGS

We observed 179 cases of new-onset asthma among 4588 participants who were free of asthma and reported at the beginning of the follow-up that they had never had asthma (4.5 per 1000 person-years). In a logistic regression, the following risk factors were found to increase the risk of new-onset asthma: female gender (OR: 1.97; 95% confidence interval (CI): 1.38, 2.81), bronchial hyperresponsiveness (3.25; 2.19, 4.83), atopy (1.55; 1.08, 2.21), FEV(1) < 100 % predicted (1.87; 1.34, 2.62), nasal allergy (1.98;1.39,2.84) and maternal asthma (1.91; 1.13; 3.21). Obesity, respiratory infections in early life and high-risk occupations increased the risk of new-onset asthma although we had limited power to confirm their role. Among the atopics, total IgE and sensitization to cat were independently related to the risk of new-onset asthma. The proportion of new-onset asthma attributable to atopy varied from 12% to 21%.

CONCLUSION

Adults reporting that they had never had asthma were at a substantial risk of new-onset asthma as a result of multiple independent risk factors including lung function. Atopy explains a small proportion of new-onset adult asthma.

The occupational contribution to severe exacerbation of asthma

The goal of this study was to identify occupational risk factors for severe exacerbation of asthma and estimate the extent to which occupation contributes to these events. The 966 participants were working adults with current asthma who participated in the follow-up phase of the European Community Respiratory Health Survey. Severe exacerbation of asthma was defined as self-reported unplanned care for asthma in the past 12 months. Occupations held in the same period were combined with a general population job-exposure matrix to assess occupational exposures. 74 participants reported having had at least one severe exacerbation event, for a 1-yr cumulative incidence of 7.7%. From regression models that controlled for confounders, the relative risk (RR) was statistically significant for low (RR 1.7, 95% CI 1.1-2.6) and high (RR 3.6, 95% CI 2.2-5.8) biological dust exposure, high mineral dust exposure (RR 1.8, 95% CI 1.02-3.2), and high gas and fumes exposure (RR 2.5, 95% CI 1.2-5.5). The summary category of high dust, gas, or fumes exposure had RR 3.1 (95% CI 1.9-5.1). Based on this RR, the population attributable risk was 14.7% among workers with current asthma. These results suggest occupation contributes to approximately one in seven cases of severe exacerbation of asthma in a working population, and various agents play a role.

Healthy hire effect, job selection and inhalation exposure among young adults with asthma

The aim of the present study was to assess whether asthma onset prior to entering the workforce influences whether a person holds a subsequent job with asthma-related inhalation exposures. The data of 19,784 adults from the European Community Respiratory Health Survey were analysed. For each respondent, a current or previously held job was linked to a job exposure matrix assigning high, low or no exposure to dust, gases or fumes. Jobs were also categorised according to the risk of exposures related to occupational asthma. Associations between asthma and subsequent occupational exposures were assessed using logistic regression models, with a random intercept for study centre and fixed adjustment for age, sex, type of study sample and smoking status. Of the respondents, 8% (n = 1,619) reported asthma with onset before completion of full-time education. This population was at decreased risk of having a job with high (odds ratio 0.79; 95% confidence interval 0.68-0.92) or low (0.91; 0.80-1.03) exposure to dust, gases or fumes. The associations were consistent across exposure types (dusts, gases or fumes) and for jobs with a high risk of occupational asthma. Adults with asthma onset prior to entering the workforce may be less likely to hold jobs involving inhalation exposures.

What defines airflow obstruction in asthma?

Asthma guidelines from the Global Initiative for Asthma (GINA) and from the National Heart, Lung, and Blood Institute provide conflicting definitions of airflow obstruction, suggesting a fixed forced expiratory volume in 1 s (FEV(1))/forced vital capacity (FVC) cut-off point and the lower limit of normality (LLN), respectively. The LLN was recommended by the recent American Thoracic Society/European Respiratory Society guidelines on lung function testing. The problem in using fixed cut-off points is that they are set regardless of age and sex in an attempt to simplify diagnosis at the expense of misclassification. The sensitivity and specificity of fixed FEV(1)/FVC ratios of 0.70, 0.75 and 0.80 versus the LLN were evaluated in 815 subjects (aged 20-44 yrs) with a diagnosis of asthma within the framework of the European Community Respiratory Health Survey. In males, the 0.70 ratio showed 76.5% sensitivity and 100.0% specificity, the 0.75 ratio 100.0% sensitivity and 92.4% specificity, and the 0.80 ratio 100.0% sensitivity but 58.1% specificity. In females, the 0.70 ratio showed 57.3% sensitivity and 100.0% specificity, the 0.75 ratio 91.5% sensitivity and 95.9% specificity, and the 0.80 ratio 100.0% sensitivity but 72.9% specificity. The fixed cut-off points cause a lot of misidentification of airflow obstruction in young adults, with overestimation with the 0.80 ratio and underestimation with the 0.70 ratio. In conclusion, the GINA guidelines should change their criteria for defining airflow obstruction.

Positionally cloned genes and age-specific effects in asthma and atopy: an international population-based cohort study (ECRHS)

BACKGROUND

Several genes identified by positional cloning have been associated with asthma and atopy, but few findings have been replicated. Age at onset of asthma has been associated with different phenotypic characteristics, and with variants at chromosome 17q21 identified through genome-wide association. This study examined the associations and age-specific effects on asthma, atopy and bronchial hyper-responsiveness (BHR) of five candidate genes previously identified by positional cloning (ADAM33, PHF11, NPSR1, DPP10, SPINK5).

METHODS

51 polymorphisms from 2474 participants from 13 countries who took part in the European Community Respiratory Health Survey (1990-2000) were studied. Asthma and age at onset of asthma were assessed by questionnaire data, BHR by methacholine challenge and atopy by specific immunoglobulin E to four common allergens.

RESULTS

Significant associations with asthma, atopy and particularly for asthma with atopy were observed for a large region of 47 kb in the NPSR1 gene, even after Bonferroni correction for multiple comparisons (p<0.001). The associations with NPSR1 were stronger in those reporting a first attack of asthma before the age of 15, with statistically significant interactions with age of onset found for three SNPs. The evidence for ADAM33 and BHR and for an age-specific effect of two SNPs in DPP10 and asthma was weaker.

CONCLUSION

This study provides further evidence for an effect of NPSR1 on asthma, atopy and atopic asthma. In addition, this analysis suggests a role for NPSR1 in early-onset asthma driven by the strong effect of this gene on atopic asthma.

Early life origins of chronic obstructive pulmonary disease

BACKGROUND

Early life development may influence subsequent respiratory morbidity. The impact of factors determined in childhood on adult lung function, decline in lung function and chronic obstructive pulmonary disease (COPD) was investigated.

METHODS

European Community Respiratory Health Survey participants aged 20-45 years randomly selected from general populations in 29 centres underwent spirometry in 1991-3 (n = 13 359) and 9 years later (n = 7738). Associations of early life factors with adult forced expiratory volume in 1 s (FEV(1)), FEV(1) decline and COPD (FEV(1)/FVC ratio <70% and FEV(1) <80% predicted) were analysed with generalised estimating equation models and random effects linear models.

RESULTS

Maternal asthma, paternal asthma, childhood asthma, maternal smoking and childhood respiratory infections were significantly associated with lower FEV(1) and defined as "childhood disadvantage factors"; 40% had one or more childhood disadvantage factors which were associated with lower FEV(1) (men: adjusted difference 95 ml (95% CI 67 to 124); women: adjusted difference 60 ml (95% CI 40 to 80)). FEV(1) decreased with increasing number of childhood disadvantage factors (> or =3 factors, men: 274 ml (95% CI 154 to 395), women: 208 ml (95% CI 124 to 292)). Childhood disadvantage was associated with a larger FEV(1) decline (1 factor: 2.0 ml (95% CI 0.4 to 3.6) per year; 2 factors: 3.8 ml (95% CI 1.0 to 6.6); > or =3 factors: 2.2 ml (95% CI -4.8 to 9.2)). COPD increased with increasing childhood disadvantage (1 factor, men: OR 1.7 (95% CI 1.1 to 2.6), women: OR 1.6 (95% CI 1.01 to 2.6); > or =3 factors, men: OR 6.3 (95% CI 2.4 to 17), women: OR 7.2 (95% CI 2.8 to 19)). These findings were consistent between centres and when subjects with asthma were excluded.

CONCLUSIONS

People with early life disadvantage have permanently lower lung function, no catch-up with age but a slightly larger decline in lung function and a substantially increased COPD risk. The impact of childhood disadvantage was as large as that of heavy smoking. Increased focus on the early life environment may contribute to the prevention of COPD.

Neuropsychologic status at the age 4 years and atopy in a population-based birth cohort

BACKGROUND

Mental health has been reported to be associated with allergy, but only a few cohort studies have assessed if neurodevelopment predicts atopy.

OBJECTIVE

To investigate if neurobehavioral status of healthy 4-year-old children was associated with specific immunoglobulin E (IgE) at the same age and skin prick test results 2 years later.

METHODS

A population-based birth cohort enrolled 482 children, 422 of them (87%) provided neurobehavioral data, 341 (71%) had specific IgE measured at the age of 4 years; and 395 (82%) had skin prick tests completed at the age of 6 years. Atopy was defined as IgE levels higher than 0.35 kU/l to any of the three tested allergens at the age of 4 or as a positive skin prick test to any of the six tested allergens at the age of 6. McCarthy Scales of Child Abilities and California Preschool Social Competence Scale were the psychometric instruments used.

RESULTS

Twelve percent of children at the age of 4 and 17% at the age of 6 were atopic. Neurobehavioral scores were negatively associated with 6-year-old atopy after adjustment for socio-demographic and allergic factors, A relative risk of 3.06 (95% CI: 1.30-7.24) was associated with the lowest tertile (scorings < or =90 points) of the general cognitive scale. Similar results were found for verbal abilities, executive functions, and social competence. Asthma, wheezing, rhinitis, and eczema at the age of 6, but not at the age of 4, were associated with neurodevelopment at the age of 4.

CONCLUSIONS

Neuropsychologic functioning and later atopy are negatively associated in preschool age children.

An international prospective general population-based study of respiratory work disability

BACKGROUND

Previous cross-sectional studies have shown that job change due to breathing problems at the workplace (respiratory work disability) is common among adults of working age. That research indicated that occupational exposure to gases, dust and fumes was associated with job change due to breathing problems, although causal inferences have been tempered by the cross-sectional nature of previously available data. There is a need for general population-based prospective studies to assess the incidence of respiratory work disability and to delineate better the roles of potential predictors of respiratory work disability.

METHODS

A prospective general population cohort study was performed in 25 centres in 11 European countries and one centre in the USA. A longitudinal analysis was undertaken of the European Community Respiratory Health Survey including all participants employed at any point since the baseline survey, 6659 subjects randomly sampled and 779 subjects comprising all subjects reporting physician-diagnosed asthma. The main outcome measure was new-onset respiratory work disability, defined as a reported job change during follow-up attributed to breathing problems. Exposure to dusts (biological or mineral), gases or fumes during follow-up was recorded using a job-exposure matrix. Cox proportional hazard regression modelling was used to analyse such exposure as a predictor of time until job change due to breathing problems.

RESULTS

The incidence rate of respiratory work disability was 1.2/1000 person-years of observation in the random sample (95% CI 1.0 to 1.5) and 5.7/1000 person-years in the asthma cohort (95% CI 4.1 to 7.8). In the random population sample, as well as in the asthma cohort, high occupational exposure to biological dust, mineral dust or gases or fumes predicted increased risk of respiratory work disability. In the random sample, sex was not associated with increased risk of work disability while, in the asthma cohort, female sex was associated with an increased disability risk (hazard ratio 2.8, 95% CI 1.3 to 5.9).

CONCLUSIONS

Respiratory work disability is common overall. It is associated with workplace exposures that could be controlled through preventive measures.

[Phenotypic characterization and course of chronic obstructive pulmonary disease in the PAC-COPD Study: design and methods]

BACKGROUND AND OBJECTIVES

The Phenotype and Course of Chronic Obstructive Pulmonary Disease (PAC-COPD) study aims to improve our understanding of the phenotypic heterogeneity of this disease and the extent to which this heterogeneity is related to clinical course. The main objectives are a) to characterize the phenotypic variability in first-time hospitalizations for exacerbation of COPD and to propose a classification into subtypes and b) to ascertain the association between the defined subtypes and the clinical and functional course of COPD.

PATIENTS AND METHODS

This is a cross-sectional and cohort study of 342 patients with COPD from 9 tertiary hospitals in 3 autonomous communities. The minimum follow-up period is 5 years. The main variables of interest are respiratory symptoms, smoking, alcohol use, physical activity, use of health care services, medical care, treatment received, activities of daily living, comorbid conditions, sleepiness, anxiety and depression, quality of life, forced spirometry and bronchodilation tests, lung volume and inspiratory capacity measured by body plethysmography, carbon monoxide diffusing capacity, baseline arterial blood gas values, respiratory and peripheral muscle function, electrocardiogram, body weight and composition measured by bioelectric impedance, chest radiograph, skin prick test, capacity for exercise measured in the 6-minute walk test and cardiopulmonary exercise test, induced sputum (for quantitative microbiological culture and determination of inflammatory markers), nighttime pulse oximetry, chest computed tomography scan, and echocardiography. Serum and plasma samples are also taken to measure levels of inflammatory markers and oxidative stress, for genetic analysis, and for other possible measurements that might be required in the future. The statistical analysis combines factor analysis and survival models such as Cox regression analysis. This project will enable us to reconsider the definition and classification of COPD and to better understand the factors associated with its natural history.

Mediterranean diet is associated with reduced asthma and rhinitis in Mexican children

BACKGROUND

Diet during pregnancy and childhood has been suggested to play an important role in children's asthma risk. We assessed whether the adherence to a Mediterranean dietary pattern, for children in the last 12 months and their mothers during pregnancy, was associated with both childhood asthma and allergic rhinitis.

METHODS

A cross-sectional study was conducted in 2004 using a random sample of 1476 children (6- to 7-year old) from the Mexicali region, Mexico. Dietary data of children's intake in the last 12 months and their mothers' intake during pregnancy was collected, through a parental food frequency questionnaire. A Mediterranean diet score was computed [Trichopoulou et al., N Engl J Med 348 (2003), 2599]. Data on seven asthma and rhinitis-related outcomes were obtained from the International Study of Asthma and Allergies in Childhood questionnaire.

RESULTS

Adherence to a Mediterranean dietary pattern was inversely associated with asthma ever (OR = 0.60, 95% CI = 0.40-0.91), wheezing ever (0.64, 0.47-0.87), rhinitis ever (0.41, 0.22-0.77), sneezing ever (0.79, 0.59-1.07), current sneezing (0.71, 0.52-0.96) and current itchy-watery eyes (0.63, 0.42-0.95). No associations were found using the mothers' pregnancy diet score, except for current sneezing (0.71, 0.53-0.97).

CONCLUSIONS

Our findings suggest a protective effect of following a healthy dietary pattern on asthma and allergic rhinitis in Mexican children.

Underestimation of airflow obstruction among young adults using FEV1/FVC <70% as a fixed cut-off: a longitudinal evaluation of clinical and functional outcomes

BACKGROUND

Early detection of airflow obstruction is particularly important among young adults because they are more likely to benefit from intervention. Using the forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) (FEV(1)/FVC) <70% fixed ratio, airflow obstruction may be underdiagnosed. The lower limit of normal (LLN), which is statistically defined by the lower fifth percentile of a reference population, is physiologically appropriate but it still needs a clinical validation.

METHODS

To evaluate the characteristics and longitudinal outcomes of subjects misidentified as normal by the fixed ratio with respect to the LLN, 6249 participants (aged 20-44 years) in the European Community Respiratory Health Survey were examined and divided into three groups (absence of airflow obstruction by the LLN and the fixed ratio; presence of airflow obstruction only by the LLN; presence of airflow obstruction by the two criteria) for 1991-1993. LLN equations were obtained from normal non-smoking participants. A set of clinical and functional outcomes was evaluated in 1999-2002.

RESULTS

The misidentified subjects were 318 (5.1%); only 45.6% of the subjects with airflow obstruction by the LLN were also identified by the fixed cut-off. At baseline, FEV(1) (107%, 97%, 85%) progressively decreased and bronchial hyperresponsiveness (slope 7.84, 6.32, 5.57) progressively increased across the three groups. During follow-up, misidentified subjects had a significantly higher risk of developing chronic obstructive pulmonary disease and a significantly higher use of health resources (medicines, emergency department visits/hospital admissions) because of breathing problems than subjects without airflow obstruction (p<0.001).

CONCLUSIONS

Our findings show the importance of using statistically derived spirometric criteria to identify airflow obstruction.

TNFA -308G>A in two international population-based cohorts and risk of asthma

Genetic association studies have related the tumour necrosis factor-alpha gene (TNFA) guanine to adenine substitution of nucleotide -308 (-308G>A) polymorphism to increased risk of asthma, but results are inconsistent. The aim of the present study was to test whether two single-nucleotide polymorphisms, of TNFA and of the lymphotoxin-alpha gene (LTA), are associated with asthma, bronchial hyperresponsiveness and atopy in adults, by combining the results of two large population-based multicentric studies and conducting a meta-analysis of previously published studies. The European Community Respiratory Health Survey (ECRHS) and Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA) used comparable protocols, including questionnaires for respiratory symptoms and measures of lung function and atopy. DNA samples from 11,136 participants were genotyped at TNFA -308 and LTA 252. Logistic regression employing fixed and random effects models and nonparametric techniques were used. The prevalence of asthma was 6%. The TNFA -308G>A polymorphism was associated with increased asthma prevalence and with bronchial hyperresponsiveness. No consistent association was found for atopy. The LTA 252A>G polymorphism was not associated with any of the outcomes. A meta-analysis of 17 studies showed an increased asthma risk for the TNFA -308 adenine allele. The tumour necrosis factor-alpha gene nucleotide -308 polymorphism is associated with a moderately increased risk of asthma and bronchial hyperresponsiveness, but not with atopy. These results are supported by a meta-analysis of previously published studies.

Long-term reliability in reporting of childhood pets by adults interviewed twice, 9 years apart. Results from the European Community Respiratory Health Survey I and II

Investigation of long-term effects of childhood pet exposure is usually based on retrospective information provided by adults, while there is little knowledge about the reliability in adult reporting of childhood events. We analyzed 8287 adults interviewed about childhood pets twice, on average nine years apart, in the European Community Respiratory Health Survey. Agreement between the surveys in reporting of childhood cats, dogs and birds were investigated with kappa statistics, and potential effects of disease status on agreement were analyzed with kappa statistics and multiple logistic regressions. Cats, dogs and birds in childhood were reported by 44, 41 and 38%, respectively. Cohen's kappa for agreement in adult reporting of childhood pets was 0.714 (95% CI=0.698-0.729) for cat, 0.709 (0.691-0.722) for dog, and 0.606 (0.591-0.626) for bird. Thus, agreement was significantly higher for reporting of cat and dog than for bird. Adult wheeze, asthma or atopy did not influence agreement. Neither did adult cat sensitization influence agreement in adult reporting of childhood cat. Childhood factors such as moving house <5 years, or growing up as a single child, in a large family or in a rural area, were associated with poorer agreement, while adult factors were unrelated to agreement.

PRACTICAL IMPLICATIONS

Long-term reliability in adult reporting of childhood pets was substantial, and not influenced by disease status. Thus, collection of information about childhood pets from adults appears to be reliable for the purpose of studying adult allergic disease. Future studies should consider that the reliability was higher for a more important childhood event and influenced by childhood rather than adult characteristics. Imperfect reliability contributed to underestimation of the effects of pets on adult allergy; i.e. with a kappa of 0.71, a true odds ratio (OR) of 0.80 would be attenuated to 0.86. Future studies should account for non-differential misclassification error.

Early exposure to dichlorodiphenyldichloroethylene, breastfeeding and asthma at age six

Our aims were to assess association of dichlorodiphenyldichloroethylene (DDE) with childhood asthma measured up to age 6 and the effect of DDE on the protective effect of breastfeeding on asthma. In addition, we attempted to assess the relevant time-window of DDE exposure (i.e. at birth or at 4 years). All women presenting for antenatal care in Menorca, Spain over a 12-month period beginning in mid-1997 were invited to take part in a longitudinal study that included a yearly visit. Four hundred eighty-two children were enrolled and 462 provided complete outcome data after 6.5 years of follow-up. Organochlorine compounds were measured in cord serum of 402 (83%) infants and in blood samples of 285 children aged 4. We defined asthma as the presence of wheezing at age 6 and during any preceding year or doctor-diagnosed asthma, and used skin prick test at age 6 to determine atopic status. Results At birth and 4 years of age, all children had detectable levels of DDE (median 1 ng/mL and 0.8 ng/mL, respectively). From birth to age 4, the mean DDE level among children with artificial feeding decreased by 72%, while among breastfed children it increased by 53%. Diagnosed asthma and persistent wheezing were associated with DDE at birth [odds ratio (OR) for an increase in 1 ng/mL, OR=1.18, 95% confidence interval (95% CI)=1.01-1.39 and OR=1.13, 95% CI=0.98-1.30, respectively], but not with DDE at 4 years. Neither breastfeeding nor atopy modified these associations (P>0.3). Breastfeeding protected against diagnosed asthma (OR=0.33, 95% CI=0.08-0.87) and wheezing (OR=0.53, 95% CI=0.34-0.82) in children with low and high DDE levels at birth. Conclusion In a community without known dichlorodiphenyltrichloroethane environmental releases, this study strengthens the evidence for an effect of DDE on asthma by measuring the disease at age 6 and does not support the hypothesis that DDE modifies the protective effect of breastfeeding on asthma.

Maternal fish intake during pregnancy and atopy and asthma in infancy

BACKGROUND

There is growing evidence that n-3 fatty acids have anti-inflammatory properties and may modulate immune response. Dietary intake of these nutrients during pregnancy could play a role in the risk of asthma and atopy in the offspring.

METHODS

Using data from a cohort of women (n=462) enrolled during pregnancy and whose offspring were followed up to 6 years, we evaluated the impact of fish consumption during pregnancy on the incidence of atopy and asthma. Dietary intake was assessed by food frequency questionnaire (42 items) applied by an interviewer.

RESULTS

Thirty-four percent of infants had a medical diagnosis of eczema at age 1 year, 14.3% of the children were atopic [based on skin prick test (SPT) at 6 years], and 5.7% had atopic wheeze at age 6 years. After adjusting for potential confounding factors, fish intake during pregnancy was protective against the risk of eczema at age 1 year, a positive SPT for house dust mite at age 6 years and atopic wheeze at age 6 years [odds ratio (OR)=0.73 95% confidence interval (CI) 0.55-0.98, OR=0.68, 95% CI 0.46-1.01 and OR=0.55, 95% CI 0.31-0.96, respectively]. For an increase in fish intake from once per week to 2.5 times per week, the risk of eczema at age 1 year decreased by 37%, and the risk of positive SPT at age 6 years by 35%. Stratification by breastfeeding showed that fish intake was significantly related to a decrease risk in persistent wheeze among non-breastfed children (P for interaction<0.05). No protective effect was observed among breastfed children.

CONCLUSION

Our data suggest a protective effect of fish intake during pregnancy on the risk of atopy-related outcomes.

Occupational risk factors for asthma among nurses and related healthcare professionals in an international study

OBJECTIVE

The authors examined the relations between self-reported work tasks, use of cleaning products and latex glove use with new-onset asthma among nurses and other healthcare workers in the European Community Respiratory Health Survey (ECRHS II).

METHODS

In a random population sample of adults from 22 European sites, 332 participants reported working in nursing and other related healthcare jobs during the nine-year ECRHS II follow-up period and responded to a supplemental questionnaire about their principal work settings, occupational tasks, products used at work and respiratory symptoms. Poisson regression models with robust error variances were used to compare the risk of new-onset asthma among healthcare workers with each exposure to that of respondents who reported professional or administrative occupations during the entire follow-up period (n = 2481).

RESULTS

Twenty (6%) healthcare workers and 131 (5%) members of the referent population reported new-onset asthma. Compared to the referent group, the authors observed increased risks among hospital technicians (RR 4.63; 95% CI 1.87 to 11.5) and among those using ammonia and/or bleach at work (RR 2.16; 95% CI 1.03 to 4.53).

CONCLUSIONS

In the ECRHS II cohort, hospital technicians and other healthcare workers experience increased risks of new-onset current asthma, possibly due to specific products used at work.

Asthma score: predictive ability and risk factors

BACKGROUND

Definition of asthma as a continuous score is a promising tool for population studies that has not yet been fully evaluated.

OBJECTIVE

We assessed (i) the predictive ability of an asthma score against the occurrence of different asthma-related outcomes and (ii) the risk factors identified when using an asthma score.

METHODS

The European Community Respiratory Health Study II included subjects from the general population randomly studied during 1991-1993 who were followed up in the years 1998-2001, from 29 centres in 14 countries. A total of 8956 subjects were included. The asthma score consisted of a simple sum of the positive answers to five respiratory symptoms.

RESULTS

Asthma score at baseline showed a linear relationship with incidence of asthma, the occurrence of asthma attacks, use of asthma medication and bronchial reactivity at the end of the follow-up. Asthma score at the end of follow-up was associated with known risk factors at baseline such as IgE to grass, rhinitis or body mass index, in addition to passive smoking in men [average score ratio (RR) = 1.30; 95% confidence interval (CI) 1.09-1.50] or changes in body mass index (RR = 1.27; 95% CI 1.05-1.27, per each kg/m(2)).

CONCLUSION

The asthma score had good predictive ability against outcomes related with asthma and also good ability to detect risk factors. This encourages the use of the score as a measure of asthma in epidemiological studies on aetiology of asthma.

Socioeconomic status, asthma and chronic bronchitis in a large community-based study

The present study investigated the relationship between socioeconomic status, using measures of occupational class and education level, and the prevalence and incidence of asthma (with and without atopy) and chronic bronchitis using data from the European Community Respiratory Health Survey (ECRHS). Asthma and chronic bronchitis were studied prospectively within the ECRHS (n = 9,023). Incidence analyses comprised subjects with no history of asthma or bronchitis at baseline. Asthma symptoms were also assessed as a continuous score. Bronchitis risk was associated with low educational level (prevalence odds ratio (POR) 1.9; 95% confidence interval (CI) 1.4-2.8) and occupational class (1.8; 1.2-2.7). Incident bronchitis also increased with low educational level (risk ratio (RR) 2.8; 95%CI 1.5-5.4). Prevalent and incident asthma with no atopy were associated with low educational level. Subjects in the low occupational class (incident risk ratio (IRR) 1.4; 95%CI 1.2-1.7) and education group (IRR 1.3; 95% CI 1.1-1.6) had higher mean asthma scores than those in higher socioeconomic groups. Lower educational level was associated with increased risk of prevalent and incident chronic bronchitis and asthma with no atopy. Lower socioeconomic groups tended to have a higher prevalence and incidence of asthma, particularly higher mean asthma scores. Adjustment for variables associated with asthma and bronchitis explained little of the observed health differences by socioeconomic status.

Changes in active and passive smoking in the European Community Respiratory Health Survey

The aim of the present investigation was to study changes and determinants for changes in active and passive smoking. The present study included 9,053 adults from 14 countries that participated in the European Community Respiratory Health Survey II. The mean follow-up period was 8.8 yrs. Change in the prevalence of active and passive smoking was expressed as absolute net change (95% confidence interval) standardised to a 10-yr period. Determinants of change were analysed and the results expressed as adjusted hazard risk ratio (HRR) or odds ratio (OR). The prevalence of active smoking declined by 5.9% (5.1-6.8) and exposure to passive smoking in nonsmokers declined by 18.4% (16.8-20.0). Subjects with a lower educational level (HRR: 0.73 (0.54-0.98) and subjects living with a smoker (HRR: 0.45 (0.34-0.59)) or with workplace smoking (HRR: 0.69 (0.50-0.95)) were less likely to quit. Low socio-economic groups were more likely to become exposed (OR: 2.21 (1.61-3.03)) and less likely to cease being exposed to passive smoking (OR: 0.48 (0.37-0.61)). In conclusion, the quitting rate was lower and the risk of exposure to passive smoking higher among subjects with lower socio-economic status. Exposure to other peoples smoking decreased quitting rates and increased the risk of starting to smoke.

Wood smoke exposure and risk of chronic obstructive pulmonary disease

It was hypothesised that wood smoke exposure could be a risk factor for chronic obstructive pulmonary disease (COPD) in Spain. The present study was designed as a case-control study of 120 females requiring hospitalisation during 2001-2003 at Hospital del Mar (Barcelona, Spain). Cases were recruited from hospital records as females who had been admitted for an exacerbation of COPD. Controls were obtained from pulmonary function test laboratory consultations prior to a surgical intervention. All patients answered a standardised questionnaire. Exposure to wood or charcoal smoke was strongly associated with COPD after adjusting for age and smoking. The association between length of exposure and COPD suggested a dose-response pattern. Intensity of exposure in both summer and winter was also related to COPD. Wood or charcoal alone independently increased risk of COPD (odds ratio (OR) 1.8 and 1.5, respectively), but only the combination of both was statistically significant (OR 4.5). In conclusion, the present study shows a strong association between wood or charcoal smoke exposure and chronic obstructive pulmonary disease, supporting its existence not only in developing countries, but also in European countries, such as Spain. Further studies assessing whether this association also exists in other European societies are warranted.

Regular physical activity reduces hospital admission and mortality in chronic obstructive pulmonary disease: a population based cohort study

BACKGROUND

Information about the influence of regular physical activity on the course of chronic obstructive pulmonary disease (COPD) is scarce. A study was undertaken to examine the association between regular physical activity and both hospital admissions for COPD and all-cause and specific mortality in COPD subjects.

METHODS

From a population-based sample recruited in Copenhagen in 1981-3 and 1991-4, 2386 individuals with COPD (according to lung function tests) were identified and followed until 2000. Self-reported regular physical activity at baseline was classified into four categories (very low, low, moderate, and high). Dates and causes of hospital admissions and mortality were obtained from Danish registers. Adjusted associations between physical activity and hospital admissions for COPD and mortality were obtained using negative binomial and Cox regression models, respectively.

RESULTS

After adjustment for relevant confounders, subjects reporting low, moderate or high physical activity had a lower risk of hospital admission for COPD during the follow up period than those who reported very low physical activity (incidence rate ratio 0.72, 95% confidence interval (CI) 0.53 to 0.97). Low, moderate and high levels of regular physical activity were associated with an adjusted lower risk of all-cause mortality (hazard ratio (HR) 0.76, 95% CI 0.65 to 0.90) and respiratory mortality (HR 0.70, 95% CI 0.48 to 1.02). No effect modification was found for sex, age group, COPD severity, or a background of ischaemic heart disease.

CONCLUSIONS

Subjects with COPD who perform some level of regular physical activity have a lower risk of both COPD admissions and mortality. The recommendation that COPD patients be encouraged to maintain or increase their levels of regular physical activity should be considered in future COPD guidelines, since it is likely to result in a relevant public health benefit.

Integrated care prevents hospitalisations for exacerbations in COPD patients

Hospital admissions due to chronic obstructive pulmonary disease (COPD) exacerbations have a major impact on the disease evolution and costs. The current authors postulated that a simple and well-standardised, low-intensity integrated care intervention can be effective to prevent such hospitalisations. Therefore, 155 exacerbated COPD patients (17% females) were recruited after hospital discharge from centres in Barcelona (Spain) and Leuven (Belgium). They were randomly assigned to either integrated care (IC; n = 65; age mean+/-sd 70+/-9 yrs; forced expiratory volume in one second (FEV(1)) 1.1+/-0.5 L, 43% predicted) or usual care (UC; n = 90; age 72+/-9 yrs; FEV(1) 1.1+/-0.05 L, 41% pred). The IC intervention consisted of an individually tailored care plan upon discharge shared with the primary care team, as well as accessibility to a specialised nurse case manager through a web-based call centre. After 12 months' follow-up, IC showed a lower hospitalisation rate (1.5+/-2.6 versus 2.1+/-3.1) and a higher percentage of patients without re-admissions (49 versus 31%) than UC without differences in mortality (19 versus 16%, respectively). In conclusion, this trial demonstrates that a standardised integrated care intervention, based on shared care arrangements among different levels of the system with support of information technologies, effectively prevents hospitalisations for exacerbations in chronic obstructive pulmonary disease patients.

Validation of an asthma questionnaire for use in healthcare workers

BACKGROUND

Previous studies have described increased occurrence of asthma among healthcare workers, but to our knowledge there are no validated survey questionnaires with which to study this occupational group.

AIMS

To develop, validate, and refine a new survey instrument on asthma for use in epidemiological studies of healthcare workers.

METHODS

An initial draft questionnaire, designed by a multidisciplinary team, used previously validated questions where possible; the occupational exposure section was developed by updating health services specific chemical lists through hospital walk-through surveys and review of material safety data sheets. A cross-sectional validation study was conducted in 118 non-smoking subjects, who also underwent bronchial challenge testing, an interview with an industrial hygienist, and measurement of specific IgE antibodies to common aeroallergens.

RESULTS

The final version consisted of 43 main questions in four sections. Time to completion of the questionnaire ranged from 13 to 25 minutes. Test-retest reliability of asthma and allergy items ranged from 75% to 94%, and internal consistency for these items was excellent (Cronbach's alpha > or = 0.86). Against methacholine challenge, an eight item combination of asthma related symptoms had a sensitivity of 71% and specificity of 70%; against a physician diagnosis of asthma, this same combination showed a sensitivity of 79% and specificity of 98%. Agreement between self-reported exposures and industrial hygienist review was similar to previous studies and only moderate, indicating the need to incorporate more reliable methods of exposure assessment. Against the aerollergen panel, the best combinations of sensitivity and specificity were obtained for a history of allergies to dust, dust mite, and animals.

CONCLUSIONS

Initial evaluation of this new questionnaire indicates good validity and reliability, and further field testing and cross-validation in a larger healthcare worker population is in progress. The need for development of more reliable occupational exposure assessment methods that go beyond self-report is underscored.

Short-term respiratory effects of cleaning exposures in female domestic cleaners

Symptoms of obstructive lung disease in domestic cleaners have been related to the use of bleach and other irritant cleaning products. The short-term effects of cleaning exposures on respiratory symptoms and peak expiratory flow (PEF) were investigated in domestic cleaners with respiratory disorders. In a panel study, 43 female domestic cleaners with a recent history of asthma and/or chronic bronchitis completed a 2-week diary, collecting information on respiratory symptoms, PEF and cleaning exposures. Mixed regression models were used to assess daily changes in symptoms and PEF associated with specific cleaning exposures. The probability of having work-related asthma was individually assessed by a computerised diagnostic system and an occupational asthma expert. Lower respiratory tract symptoms were more common on working days and were predominantly associated with exposure to diluted bleach, degreasing sprays/atomisers and air fresheners. Associations with upper respiratory tract symptoms and PEF were less apparent. Eleven (30%) subjects scored positively for work-related asthma. It is concluded that exposure to certain irritant cleaning products aggravates lower respiratory tract symptoms in female domestic cleaners with asthma or chronic bronchitis.

Maternal atopy and changes in parity

BACKGROUND

Atopic women tend to have fewer children, although atopy may favour conception.

OBJECTIVE

To assess whether atopy is associated with the number of new births and whether changes in parity are associated with a change in atopy in a cohort of young women.

METHODS

Women had atopy (defined as the presence of serum-specific IgE against common aeroallergens) measured in the European Community Respiratory Health Study during the years 1991--92 (n=4580). About 9 years later, 2844 (62.1%) were recontacted and 2414 (52.7%) had atopy measured again.

RESULTS

Atopic women had fewer children at baseline than non-atopic women but the association disappeared at the end of the follow-up. Atopy tended to increase parity during the follow-up, but in a non-statistically significant way (relative risk=1.08; 0.86-1.35, after adjusting for number of children at baseline, age, length of follow-up, education or social class). Prevalence of atopy during the follow-up changed by the same magnitude whatever the birth cohort and the change in the number of children (P for interaction >0.7).

CONCLUSION

Atopic women did not have a significantly higher fertility rate but they may postpone having their first child compared with non-atopic women. We are unable to confirm the hypothesis that atopy in women may decrease with successive pregnancies.