Early life factors associated with incidence of physician-diagnosed asthma in preschool children: results from the Canadian Early Childhood Development cohort study

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

Whispers of change in preschool asthma phenotypes: Findings in the French ELFE cohort

RATIONALE

Early life asthma phenotyping remains an unmet need in pediatric asthma. In France, severe pediatric asthma phenotyping has been done extensively; however, phenotypes in the general population remain underexplored. Based on the course and severity of respiratory/allergic symptoms, we aimed to identify and characterize early life wheeze profiles and asthma phenotypes in the general population.

METHODS

ELFE is a general population based birth cohort; which recruited 18,329 newborns in 2011, from 320 maternity units nationwide. Data was collected using parental responses to modified versions of ISAAC questionnaire on eczema, rhinitis, food allergy, cough, wheezing, dyspnoea and sleep disturbance due to wheezing at 3 time points: post-natal (2 months), infancy (age 1) and pre-school (age 5). We built a supervised trajectory for wheeze profiles and an unsupervised approach was used for asthma phenotypes. Chi squared (χ2) test or fisher's exact test was used as appropriate (p < 0.05).

RESULTS

Wheeze profiles and asthma phenotypes were ascertained at age 5. Supervised wheeze trajectory of 9161 children resulted in 4 wheeze profiles: Persistent (0.8%), Transient (12.1%), Incident wheezers at age 5 (13.3%) and Non wheezers (73.9%). While 9517 children in unsupervised clusters displayed 4 distinct asthma phenotypes: Mildly symptomatic (70%), Post-natal bronchiolitis with persistent rhinitis (10.2%), Severe early asthma (16.9%) and Early persistent atopy with late onset severe wheeze (2.9%).

CONCLUSION

We successfully determined early life wheeze profiles and asthma phenotypes in the general population of France.

Geographical Differences of Risk of Asthma and Allergic Rhinitis according to Urban/Rural Area: a Systematic Review and Meta-analysis of Cohort Studies

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).

Risk Factors Affecting Development and Persistence of Preschool Wheezing: Consensus Document of the Emilia-Romagna Asthma (ERA) Study Group

Wheezing at preschool age (i.e., before the age of six) is common, occurring in about 30% of children before the age of three. In terms of health care burden, preschool children with wheeze show double the rate of access to the emergency department and five times the rate of hospital admissions compared with school-age asthmatics. The consensus document aims to analyse the underlying mechanisms involved in the pathogenesis of preschool wheezing and define the risk factors (i.e., allergy, atopy, infection, bronchiolitis, genetics, indoor and outdoor pollution, tobacco smoke exposure, obesity, prematurity) and the protective factors (i.e., probiotics, breastfeeding, vitamin D, influenza vaccination, non-specific immunomodulators) associated with the development of the disease in the young child. A multidisciplinary panel of experts from the Emilia-Romagna Region, Italy, addressed twelve key questions regarding managing preschool wheezing. Clinical questions have been formulated by the expert panel using the PICO format (Patients, Intervention, Comparison, Outcomes). Systematic reviews have been conducted on PubMed to answer these specific questions and formulate recommendations. The GRADE approach has been used for each selected paper to assess the quality of the evidence and the degree of recommendations. Based on a panel of experts and extensive updated literature, this consensus document provides insight into the pathogenesis, risk and protective factors associated with the development and persistence of preschool wheezing. Undoubtedly, more research is needed to improve our understanding of the disease and confirm the associations between certain factors and the risk of wheezing in early life. In addition, preventive strategies must be promoted to avoid children's exposure to risk factors that may permanently affect respiratory health.

Home Environment in Early-Life and Lifestyle Factors Associated with Asthma and Allergic Diseases among Inner-City Children from the REPRO_PL Birth Cohort

OBJECTIVE

We hypothesized that, in our REPRO_PL cohort, exposure to indoor allergens and lifestyle factors in early life are associated with risk of asthma, atopic dermatitis, and allergic rhinitis at ten years of age.

METHODS

We only examined children who had lived in the same house from birth. Children's exposure to tobacco smoke was assessed based on cotinine levels in urine. House dust samples were collected.

RESULTS

Higher Fel d1 concentration in house dust was associated with significantly higher risk of developing asthma at age 10 years (95% CI,10.87 to 20.93; p < 0.001). Frequent house cleaning was associated with development of atopic dermatitis (odds ratio 0.61; 95% CI 0.37 to 0.99; p = 0.045). Clustering of exposure to HDM revealed two types of environment. Cluster 1, defined as lower HDM (dust), in contrast to Cluster 2, defined as higher HDM, was characterized by old-type windows, lower fungus and dampness levels, as well as more frequent house cleaning.

CONCLUSION

Exposure to cat allergens and new-type buildings that limit air flow while increasing the condensation of steam on the windows and thereby stimulating the growth of fungi are risk factors for the development of asthma.

Machine Learning for Predicting the Risk for Childhood Asthma Using Prenatal, Perinatal, Postnatal and Environmental Factors

The prevalence rate for childhood asthma and its associated risk factors vary significantly across countries and regions. In the case of Morocco, the scarcity of available medical data makes scientific research on diseases such as asthma very challenging. In this paper, we build machine learning models to predict the occurrence of childhood asthma using data from a prospective study of 202 children with and without asthma. The association between different factors and asthma diagnosis is first assessed using a Chi-squared test. Then, predictive models such as logistic regression analysis, decision trees, random forest and support vector machine are used to explore the relationship between childhood asthma and the various risk factors. First, data were pre-processed using a Chi-squared feature selection, 19 out of the 36 factors were found to be significantly associated (p-value < 0.05) with childhood asthma; these include: history of atopic diseases in the family, presence of mites, cold air, strong odors and mold in the child's environment, mode of birth, breastfeeding and early life habits and exposures. For asthma prediction, random forest yielded the best predictive performance (accuracy = 84.9%), followed by logistic regression (accuracy = 82.57%), support vector machine (accuracy = 82.5%) and decision trees (accuracy = 75.19%). The decision tree model has the advantage of being easily interpreted. This study identified important maternal and prenatal risk factors for childhood asthma, the majority of which are avoidable. Appropriate steps are needed to raise awareness about the prenatal risk factors.

Maternal preconception occupational exposure to cleaning products and disinfectants and offspring asthma

BACKGROUND

Emerging research suggests health effects in offspring after parental chemical exposures before conception. Many future mothers are exposed to potent chemicals at work, but potential offspring health effects are hardly investigated.

OBJECTIVE

We sought to investigate childhood asthma in relation to mother's occupational exposure to cleaning products and disinfectants before conception.

METHODS

The multicenter Respiratory Health In Northern Europe/Respiratory Health In Northern Europe, Spain and Australia generation study investigated asthma and wheeze starting at age less than 10 years in 3318 mother-offspring pairs. From an asthma-specific Job-Exposure Matrix and mothers' occupational history, we defined maternal occupational exposure to indoor cleaning agents (cleaning products/detergents and disinfectants) starting before conception, in the 2-year period around conception and pregnancy, or after birth. Never-employed mothers were excluded. Exposed groups include cleaners, health care workers, cooks, and so forth. Associations were analyzed using mixed-effects logistic regression and ordinary logistic regression with clustered robust SEs and adjustment for maternal education.

RESULTS

Maternal occupational exposure to indoor cleaning starting preconception and continuing (n = 610) was associated with offspring's childhood asthma: odds ratio 1.56 (95% CI, 1.05-2.31), childhood asthma with nasal allergies: 1.77 (1.13-2.77), and childhood wheeze and/or asthma: 1.71 (95% CI, 1.19-2.44). Exposure starting around conception and pregnancy (n = 77) was associated with increased childhood wheeze and/or asthma: 2.25 (95% CI, 1.03-4.91). Exposure starting after birth was not associated with asthma outcomes (1.13 [95% CI, 0.71-1.80], 1.15 [95% CI, 0.67-1.97], 1.08 [95% CI, 0.69-1.67]).

CONCLUSIONS

Mother's occupational exposure to indoor cleaning agents starting before conception, or around conception and pregnancy, was associated with more childhood asthma and wheeze in offspring. Considering potential implications for vast numbers of women in childbearing age using cleaning agents, and their children, further research is imperative.

Atopic diseases and airway-related symptoms in Bavarian pre-schoolers: determinants and association with immunization

BACKGROUND

Atopic diseases are among the most common chronic conditions in childhood. Causes of allergies are manifold. The aim of this paper is to evaluate risk factors for atopic diseases and unremitting wheeze and to examine if there is an association between measles, mumps and rubella (MMR) vaccination and atopic dermatitis, asthma and unremitting wheeze in Bavarian pre-schoolers.

METHODS

Parents filled out a questionnaire on children's health and environmental and socioeconomic factors. The questionnaire was administered within the Health Monitoring Units in a cross-sectional study in Bavaria, Germany (2014/2015). Data on vaccinations were obtained via the School Entrance Examination, a mandatory examination for pre-school children in Bavaria. Rates of influential factors of atopic diseases and wheeze, MMR and DTP (diphtheria, pertussis and tetanus) vaccination were calculated for all children stratified by health outcomes. To examine if there is an association between MMR vaccination and health outcomes, a multiple logistic regression analysis was performed.

RESULTS

Data were available for 3237 individuals. Symptoms and diseases were more frequent in boys. Higher parental education was associated with a higher prevalence of atopic dermatitis. There were no significant associations between any of the health outcome groups and MMR vaccination in the multiple logistic regression models with adjustment for potential confounders.

CONCLUSIONS

The present study is in line with the current state of research that MMR vaccination is not associated with atopic diseases.

A Quasi-Experimental Study of the Effects of Pre-Kindergarten Education on Pediatric Asthma

Ensuring access to pre-kindergarten (Pre-K) education remains a pressing policy issue in the United States. Prior research has shown the positive effects that Pre-K has on children’s cognitive development. However, studies on its effects on children’s health outcomes are scarce. This study aimed to investigate the effects of the Pre-K program on pediatric asthma. Children’s individual data from existing research conducted in North Carolina were linked with state Medicaid claims data from 2011–2017. There were 51,408 observations (person-month unit) of 279 children enrolled in Pre-K and 333 unenrolled children. Asthma was identified using the ICD 9/10 codes. A difference-in-differences model was adopted using a panel analysis with three time periods: before, during, and after Pre-K. The explanatory variables were interaction terms between Pre-K enrollment and (a) before vs. during period and (b) during vs. after period. The results indicated that children enrolled in Pre-K had a greater risk of asthma diagnosis during Pre-K (b = 0.0145, p = 0.058). Conversely, in the post-intervention period, the enrolled children had a lower of receiving an asthma diagnosis (b = −0.0216, p = 0.002). These findings indicate that Pre-K may increase the use of asthma-related health services in the short term and decrease the service use after participants leave the program.

Breastfeeding and risk of childhood asthma: a systematic review and meta-analysis

OBJECTIVE

To investigate the relationship between breastfeeding and the development of paediatric asthma.

METHODS

A systematic review and meta-analysis was conducted with MEDLINE, Embase, CINAHL and ProQuest Nursing and Allied Health source databases. Retrospective/prospective cohorts in children aged <18 years with breastfeeding exposure reported were included. The primary outcome was a diagnosis of asthma by a physician or using a guideline-based criterion. A secondary outcome was asthma severity.

RESULTS

42 studies met inclusion criteria. 37 studies reported the primary outcome of physician-/guideline-diagnosed asthma, and five studies reported effects on asthma severity. Children with longer duration/more breastfeeding compared to shorter duration/less breastfeeding have a lower risk of asthma (OR 0.84, 95% CI 0.75-0.93; I2 = 62.4%). Similarly, a lower risk of asthma was found in children who had more exclusive breastfeeding versus less exclusive breastfeeding (OR 0.81, 95% CI 0.72-0.91; I2=44%). Further stratified analysis of different age groups demonstrated a lower risk of asthma in the 0-2-years age group (OR 0.73, 95% CI 0.63-0.83) and the 3-6-years age group (OR 0.69, 95% CI 0.55-0.87); there was no statistically significant effect on the ≥7-years age group.

CONCLUSION

The findings suggest that the duration and exclusivity of breastfeeding are associated with a lower risk of asthma in children aged <7 years.

Association between vesicoureteral reflux, urinary tract infection and antibiotics exposure in infancy and risk of childhood asthma

Background

The use of antibiotics for treating infection in childhood and their association with increased risk of asthma remain controversial. Infants diagnosed with vesicoureteral reflux (VUR) belong to a unique population who are administered antibiotics for a long time and are susceptible to recurrent UTI. It is interesting to study the risk of asthma in these infants with or without VUR.

Methods

Taiwanese children born between 2000 and 2007 were enrolled in population-based birth cohort study. Participants diagnosed with VUR and UTI within first year were classified into four groups (VUR, UTI, VUR and UTI, and control). We calculated follow-up person-years for each participant from the index date until the asthma diagnosis, their withdrawal from the insurance system (because of death or loss to follow-up), or till the end of 2008. The risk of asthma was compared between the 4 cohorts by using Cox proportional hazards model analysis, adjusted hazard ratio (aHR), and 95% confidence interval (95% CI).

Results

Children diagnosed with VUR (n  =  350), UTI (n  =  15542), VUR and UTI (n  =  1696), and randomly selected controls (n  =  17588) were enrolled. The overall rate of incidence of asthma was found to be 1.64-fold, 1.45-fold, and 1.17-fold higher in the UTI, VUR/UTI, and VUR cohorts than in the controls (5.60, 5.07, and 4.10 vs. 3.17 per 100 person-years), respectively. After adjusting the potential factors, the overall risk of asthma remained the highest in UTI (aHR: 1.74, 95% CI : 1.65 to 1.80) followed by VUR/UTI (aHR: 1.56, 95% CI : 1.40 to 1.75) and VUR cohorts (aHR: 1.25, 95% CI: 0.96 to 1.62). The incidence of asthma was higher in boys than in girls.

Conclusion

The nationwide retrospective cohort study demonstrated that short-term therapeutic dose of antibiotics for UTI in infants with or without VUR has a positive correlation with the prevalence of childhood asthma. Significant risk of childhood asthma was not observed when VUR cohort was exposed to long-term low-dose of prophylactic antibiotics.

Inactivation of common airborne antigens by perfluoroalkyl chemicals modulates early life allergic asthma

Allergic asthma, driven by T helper 2 cell-mediated immune responses to common environmental antigens, remains the most common respiratory disease in children. Perfluorinated chemicals (PFCs) are environmental contaminants of great concern, because of their wide application, persistence in the environment, and bioaccumulation. PFCs associate with immunological disorders including asthma and attenuate immune responses to vaccines. The influence of PFCs on the immunological response to allergens during childhood is unknown. We report here that a major PFC, perfluorooctane sulfonate (PFOS), inactivates house dust mite (HDM) to dampen 5-wk-old, early weaned mice from developing HDM-induced allergic asthma. PFOS further attenuates the asthma protective effect of the microbial product lipopolysaccharide (LPS). We demonstrate that PFOS prevents desensitization of lung epithelia by LPS, thus abolishing the latter's protective effect. A close mechanistic study reveals that PFOS specifically binds the major HDM allergen Der p1 with high affinity as well as the lipid A moiety of LPS, leading to the inactivation of both antigens. Moreover, PFOS at physiological human (nanomolar) concentrations inactivates Der p1 from HDM and LPS in vitro, although higher doses did not cause further inactivation because of possible formation of PFOS aggregates. This PFOS-induced neutralization of LPS has been further validated in primary human cell models and extended to an in vivo bacterial infection mouse model. This study demonstrates that early life exposure of mice to a PFC blunts airway antigen bioactivity to modulate pulmonary inflammatory responses, which may adversely affect early pulmonary health.

Risk of asthma in children diagnosed with bronchiolitis during infancy: protocol of a longitudinal cohort study linking emergency department-based clinical data to provincial health administrative databases

INTRODUCTION

The Canadian Bronchiolitis Epinephrine Steroid Trial (CanBEST) and the Bronchiolitis Severity Cohort (BSC) study enrolled infants with bronchiolitis during the first year of life. The CanBEST trial suggested that treatment of infants with a combined therapy of high-dose corticosteroids and nebulised epinephrine reduced the risk of admission to hospital. Our study aims to-(1) quantify the risk of developing asthma by age 5 and 10 years in children treated with high-dose corticosteroid and epinephrine for bronchiolitis during infancy, (2) identify risk factors associated with development of asthma in children with bronchiolitis during infancy, (3) develop asthma prediction models for children diagnosed with bronchiolitis during infancy.

METHODS AND ANALYSIS

We propose a longitudinal cohort study in which we will link data from the CanBEST and BSC study with routinely collected data from provincial health administrative databases. Our outcome is asthma incidence measured using a validated health administrative data algorithm. Primary exposure will be treatment with a combined therapy of high-dose corticosteroids and nebulised epinephrine for bronchiolitis. Covariates will include type of viral pathogen, disease severity, medication use, maternal, prenatal, postnatal and demographic factors and variables related to health service utilisation for acute lower respiratory tract infection. The risk associated with development of asthma in children treated with high-dose corticosteroid and epinephrine for bronchiolitis will be assessed using multivariable Cox proportional hazards regression models. Prediction models will be developed using multivariable logistic regression analysis and internally validated using a bootstrap approach.

ETHICS AND DISSEMINATION

Our study has been approved by the ethics board of all four participating sites of the CanBEST and BSC study. Finding of the study will be disseminated to the academic community and relevant stakeholders through conferences and peer-reviewed publications.

TRIAL REGISTRATION NUMBER

ISRCTN56745572; Post-results.

Family functioning according to clusters of family management styles in Korean families of children with chronic atopic disease: A cross-sectional study

BACKGROUND

Chronic allergic diseases in children are often linked with behavioral problems, poor daily living, negative perceptions of health, and low life satisfaction.

OBJECTIVES

This study aimed to propose clusters of family management styles in the Korean families of children with chronic atopic disease, including allergic asthma, atopic dermatitis, and/or allergic rhinitis and examine the level of family functioning according to these clusters.

DESIGN

Cross-sectional study.

SETTINGS

A university-level hospital in metropolitan Seoul, South Korea.

PARTICIPANTS

Parents of children with chronic atopic disease.

METHODS

This study included 146 participants. The Korean version of the Family Management Measure and the Korean Family Functioning Scale were used to assess family management styles and family functioning, respectively. Data were analyzed using SPSS 24.0 using descriptive statistics, agglomerative hierarchical clustering with Ward's method prior to k-means clustering, k-means clustering analysis, analysis of variance, and chi-squared test.

RESULTS

Four clusters of family management styles were identified as follows: stable-resilient, less committed, parents' mission, and challenging. Among all participants, 19.9%, 30%, 20.6%, and 29.5% belonged to each of these clusters, respectively. The level of family functioning significantly differed between the four clusters, with the stable-resilient cluster having the highest mean level and the challenging cluster having the lowest mean level. Parents' perceived the complexity of self-managing their child's condition as one of the factors differentiating the level of family functioning of each cluster.

CONCLUSIONS

This study identified four clusters of family management styles and showed that each cluster was associated with a different level of family functioning. The unique characteristics of the four clusters may be helpful in providing individualized care and promoting positive family functioning in families with children having chronic atopic disease.

Associations between Neighborhood Walkability and Incident and Ongoing Asthma in Children

RATIONALE

Childhood asthma has shown variable associations with children's physical activity. Neighborhood walkability captures community features that promote walking and is protective against some chronic conditions, such as obesity and diabetes.

OBJECTIVES

We evaluated associations between home neighborhood walkability and incident and ongoing childhood asthma.

METHODS

In this population-based cohort study, we used prospectively collected administrative healthcare data for the Province of Ontario housed at the Institute for Clinical Evaluative Sciences. We followed an administrative data cohort of 326,383 Toronto children born between 1997 and 2003, inclusive, until ages 8-15 years. Home neighborhood walkability quintile was measured using a validated walkability index with four dimensions: population density, dwelling density, access to retail and services, and street connectivity. Incident asthma was defined by time of entry into the validated Ontario Asthma Surveillance Information System database, which requires two outpatient visits for asthma within two consecutive years or any hospitalization for asthma and follows children with asthma longitudinally starting at any age. Associations between walkability and incident asthma were examined using Cox proportional hazards models. Associations between ongoing asthma and walkability in each year of life were examined using generalized linear mixed models.

RESULTS

Twenty-one percent of children (n = 69,628) developed incident asthma and were followed longitudinally in the Ontario Asthma Surveillance Information System database. Low birth home neighborhood walkability was associated with an increased incidence of asthma (hazard ratio, 1.11; 95% confidence interval, 1.08-1.14). Among children with asthma, low walkability in a given year of a child`s life was associated with greater odds of ongoing asthma in the same year (odds ratio, 1.12; 95% confidence interval, 1.09-1.14).

CONCLUSIONS

Children living in neighborhoods with low walkability were at increased risk of incident and ongoing asthma. Neighborhood walkability improvement, such as by adding pedestrian paths to improve street connectivity, offers potential strategies to contribute to primary asthma prevention.

Neighborhood Material Deprivation Is Associated with Childhood Asthma Development: Analysis of Prospective Administrative Data

Rationale

Material deprivation has been proposed as a more comprehensive measure of socioeconomic status than parental income. Stronger associations between childhood emergency department visits for asthma and air pollution have been demonstrated among children living in neighborhoods with high levels of deprivation, but the associations with asthma development and ongoing asthma are not known.

Objectives

We determined the associations between neighborhood material deprivation and the development of new and ongoing childhood asthma.

Methods

Prospectively collected administrative data housed at the Institute for Clinical Evaluative Sciences were examined for Toronto children born from 1997 to 2003. Neighborhood material deprivation, comprising no high school graduation, lone parent families, government transfers, unemployment, low income, and homes needing major repairs, was reported in the Ontario Marginalization Index. Incident asthma was defined by the time of entry into the Ontario Asthma Surveillance Information System (OASIS) database. We measured the risk of incident asthma using Cox proportional hazards models and the associations between ongoing asthma visits and deprivation by year of life with generalized linear mixed models.

Results

OASIS asthma criteria were met for 21% of the 326,383 children. After adjustment for characteristics strongly associated with asthma, including male sex, prematurity, obesity, and atopic conditions other than asthma, children with high birth neighborhood deprivation were at increased risk of incident asthma (HR 1.11; 95% CI, 1.09–1.13). High deprivation in a given year of life was associated with increased odds of ongoing asthma during that year of life (OR 1.03; 95% CI, 1.02–1.05).

Conclusions

Children living in high-deprivation neighborhoods are at increased risk of incident and ongoing asthma. This study suggests that neighborhood material deprivation may represent a helpful tool for evaluating the effects of disparities in health and social advantages on the likelihood of developing and continuing to need healthcare visits for ongoing childhood asthma.

Genetic Architectures of Childhood- and Adult-Onset Asthma Are Partly Distinct

The extent to which genetic risk factors are shared between childhood-onset (COA) and adult-onset (AOA) asthma has not been estimated. On the basis of data from the UK Biobank study (n = 447,628), we found that the variance in disease liability explained by common variants is higher for COA (onset at ages between 0 and 19 years; h²_g = 25.6%) than for AOA (onset at ages between 20 and 60 years; h²_g = 10.6%). The genetic correlation (r_g) between COA and AOA was 0.67. Variation in age of onset among COA-affected individuals had a low heritability (h²_g = 5%), which we confirmed in independent studies and also among AOA-affected individuals. To identify subtype-specific genetic associations, we performed a genome-wide association study (GWAS) in the UK Biobank for COA (13,962 affected individuals) and a separate GWAS for AOA (26,582 affected individuals) by using a common set of 300,671 controls for both studies. We identified 123 independent associations for COA and 56 for AOA (37 overlapped); of these, 98 and 34, respectively, were reproducible in an independent study (n = 262,767). Collectively, 28 associations were not previously reported. For 96 COA-associated variants, including five variants that represent COA-specific risk factors, the risk allele was more common in COA- than in AOA-affected individuals. Conversely, we identified three variants that are stronger risk factors for AOA. Variants associated with obesity and smoking had a stronger contribution to the risk of AOA than to the risk of COA. Lastly, we identified 109 likely target genes of the associated variants, primarily on the basis of correlated expression quantitative trait loci (up to n = 31,684). GWAS informed by age of onset can identify subtype-specific risk variants, which can help us understand differences in pathophysiology between COA and AOA and so can be informative for drug development.

Infant milk-feeding practices and food allergies, allergic rhinitis, atopic dermatitis, and asthma throughout the life span: a systematic review

BACKGROUND

During the Pregnancy and Birth to 24 Months Project, the USDA and Department of Health and Human Services initiated a review of evidence on diet and health in these populations.

OBJECTIVES

The aim of these systematic reviews was to examine the relation of 1) never versus ever feeding human milk, 2) shorter versus longer durations of any human milk feeding, 3) shorter versus longer durations of exclusive human milk feeding prior to infant formula introduction, 4) feeding a lower versus higher intensity of human milk to mixed-fed infants, and 5) feeding a higher intensity of human milk by bottle versus breast with food allergies, allergic rhinitis, atopic dermatitis, and asthma.

METHODS

The Nutrition Evidence Systematic Review team conducted systematic reviews with external experts. We searched CINAHL, Cochrane, Embase, and PubMed for articles published between January 1980 and March 2016, dual-screened the results according to predetermined criteria, extracted data from and assessed the risk of bias for each included study, qualitatively synthesized the evidence, developed conclusion statements, and graded the strength of the evidence.

RESULTS

The systematic reviews numbered 1-5 above included 44, 35, 1, 0, and 0 articles, respectively. Moderate, mostly observational, evidence suggests that 1) never versus ever being fed human milk is associated with higher risk of childhood asthma, and 2) among children and adolescents who were fed human milk as infants, shorter versus longer durations of any human milk feeding are associated with higher risk of asthma. Limited evidence does not suggest associations between 1) never versus ever being fed human milk and atopic dermatitis in childhood or 2) the duration of any human milk feeding and allergic rhinitis and atopic dermatitis in childhood.

CONCLUSIONS

Moderate evidence suggests that feeding human milk for short durations or not at all is associated with higher childhood asthma risk. Evidence on food allergies, allergic rhinitis, and atopic dermatitis is limited.

Asthma, Rhinoconjunctivitis, Eczema, and the Association with Perinatal Anthropometric Factors in Vietnamese Children

Few studies have investigated possible causative and protective factors associated with allergic diseases in resource-limited countries, Southeast Asia. We estimated the current prevalence of asthma, rhinoconjunctivitis, and eczema among 6-year-old children, and identified anthropometric factors associated with asthma, rhinoconjunctivitis and eczema, in South-Central Vietnam. A birth cohort study recruited 1,999 children born at a provincial hospital in Nha Trang, Vietnam between May 2009 and May 2010. A 6-year follow-up survey was conducted where clinical, familial, and environmental information was collected by interviewing caregivers using a standardized form based on the International Study of Asthma and Allergies in Childhood, Phase Three Core and Environmental Questionnaire for 6–7-year-old children. The odds ratios of asthma, rhinoconjunctivitis, and eczema for anthropometric factors were estimated using logistic regression analysis. In total, 1202 children participated in the follow-up survey. The proportions of children who had current asthma, rhinoconjunctivitis, and eczema were 5.1% (95% confidence interval [CI] 3.9–6.5%), 11.5% (9.7–13.4%), and 6.7% (5.3–8.2%), respectively. Low birthweight (adjusted odds ratio 5.12, 95% CI 1.92–13.64) was independently associated with increased risk of eczema. Further studies are necessary to understand the involved mechanism.

Association of early daycare attendance with allergic disorders in children: a longitudinal national survey in Japan

The association between early daycare attendance and risk of allergic diseases remains inconclusive. Therefore, we examined the association among Japanese children on a long-term basis using a nationwide longitudinal survey data. We estimated the association between daycare attendance at age 6 or 18 months and allergy development using information on outpatient visits for atopic dermatitis (AD), food allergy (FA), and asthma and admission for asthma up to 12 years of age as a proxy for developing these diseases, with multilevel logistic regression. Early daycare attendance was associated with increased odds of AD at ages 2.5-3.5 years: the adjusted odds ratio (OR) was 1.34 [95% CI: 1.21, 1.47]. The association with FA was equivocal. The odds of asthma was increased before age 3.5 years and afterwards decreased: the adjusted ORs were 1.60 [1.44, 1.77] for ages 1.5-2.5 years and 0.77 [0.69, 0.87] for ages 5.5-7 years. The effect of early daycare attendance depends on the type of allergies.

Prenatal Maternal Depressive Symptoms Predict Early Infant Health Concerns

INTRODUCTION

Recent research suggests that health disparities among low-SES and ethnic minority populations may originate from prenatal and early life exposures. Postpartum maternal depressive symptoms have been linked to poorer infant physical health, yet prenatal depressive symptoms not been thoroughly examined in relation to infant health.

METHODS

In a prospective study of low-income Mexican American mothers and their infants, women (N = 322, median age 27.23, IQR = 22.01-32.54) completed surveys during pregnancy (median gestation 39.50, IQR = 38.71-40.14 weeks) and 12 weeks after birth. We investigated (1) if prenatal depressive symptoms predicted infant physical health concerns at 12 weeks of age, (2) whether these associations occurred above and beyond concurrent depressive symptoms, and (3) if birth weight, gestational age, and breastfeeding were mediators of prenatal depression predicting subsequent infant health.

RESULTS

Higher prenatal depressive symptoms were associated with more infant physical health concerns at 12 weeks (p < .001), after accounting for 12-week maternal depressive symptoms, breastfeeding, gestational age, and birth weight. Twelve-week maternal depressive symptoms were concurrently associated with more infant health concerns (p < .01). Birth weight, gestational age, and breastfeeding were not associated with maternal depression or infant health concerns.

DISCUSSION

Results establish a link between prenatal depressive symptoms and an elevated risk of poor health evident shortly after birth. These findings underscore the importance of the prenatal period as a possible sensitive period for infants' health, and the need for effective interventions for depression during pregnancy to mitigate potentially teratogenic effects on the developing fetus and reduce risks for later health concerns.

The association of prenatal risk factors with childhood asthma

Objective: The purpose of the study was to examine the relationship of maternal complications during pregnancy and prenatal exposures with childhood asthma among low-income families in Karachi, Pakistan. Methods: Parents/guardians of children with and without asthma visiting a charity hospital were enrolled. Information about prenatal and perinatal exposures was collected. Univariable and multiple stepwise logistic regression analysis were conducted to explore the relationship of socio-demographic, maternal complications during pregnancy, access to prenatal care, and exposure to animals and pests while pregnant with childhood asthma. Results: Maternal symptoms of nocturnal cough (adjusted OR [aOR = 2.87, 95% CI = 1.60-5.14) and wheezing (aOR = 5.57, 95% CI = 2.32-13.37) during pregnancy significantly increased the odds of childhood asthma. The family history of asthma or hay fever, also elevated the odds of childhood asthma (adjusted OR [aOR] = 5.86 (3.03-11.34). The odds of asthma among children whose mothers received prenatal care by Dai, an unskilled health worker, were significantly elevated. Lastly, prenatal exposure to rats/mice and contact with goats while pregnant was significantly associated with childhood asthma. Whereas, prenatal exposure to cows/cattle reduces the odds of childhood asthma. Conclusions: This study identified important maternal and prenatal risk factors for childhood asthma, the majority of which are avoidable. Appropriate steps are needed to create awareness about the prenatal risk factors in this population.

The impact of maternal smoking during pregnancy on childhood asthma: adjusted for exposure misclassification; results from the National Health and Nutrition Examination Survey, 2011-2012

PURPOSE

We sought to examine the association between childhood asthma and self-reported maternal smoking during pregnancy (MSDP) after adjusting for a range of exposure misclassification scenarios using a Bayesian approach that incorporated exposure misclassification probability estimates from the literature.

METHODS

Self-reported MSDP and asthma data were extracted from National Health and Nutrition Examination Survey 2011-2012. The association between self-reported MSDP and asthma was adjusted for exposure misclassification using a Bayesian bias model approach.

RESULTS

We included 3074 subjects who were 1-15 years of age, including 492 asthma cases. The mean (SD) of age of the participants was 8.5 (4.1) and 7.1 (4.2) years and the number (percentage) of female was 205 (42%) and 1314 (51%) among asthmatic and nonasthmatic groups, respectively. The odds ratio (OR) for the association between self-reported MSDP and asthma in logistic regression adjusted for confounders was 1.28 (95% confidence interval: 0.92, 1.77). In a Bayesian analysis that adjusted for exposure misclassification using external data, we found different ORs between MSDP and asthma by applying different priors (posterior ORs 0.90 [95% credible interval {CRI}: 0.47, 1.60] to 3.05 [95% CRI: 1.73, 5.53] in differential and 1.22 [CRI 95%: 0.62, 2.25] to 1.60 CRI: 1.18, 2.19) in nondifferential misclassification settings.

CONCLUSIONS

Given the assumptions and the accuracy of the bias model, the estimated effect of MSDP on asthma after adjusting for misclassification was strengthened in many scenarios.

The effect of early child care attendance on childhood asthma and wheezing: A meta-analysis

OBJECTIVE

Research evidence offers mixed results regarding the relationship between early child care attendance and childhood asthma and wheezing. A meta-analysis was conducted to synthesize the current research evidence of the association between early child care attendance and the risk of childhood asthma and wheezing.

METHOD

Peer reviewed studies published from 1964-January 2017 were identified in MEDLINE, CINAL, and EMBASE using MeSH headings relevant to child care and asthma. Two investigators independently reviewed the selected articles from this search. All relevant articles that met our inclusion criteria were selected for further analysis. Data were extracted from studies that had sufficient data to analyze the odds of asthma or wheezing among children who attended child care.

RESULTS

The meta-analysis of 32 studies found that (1) early child care attendance is protective against asthma in children 3-5 years of age but not for children with asthma 6 years of age or older. (2) Early child care attendance increases the risk of wheezing among children 2 years of age or younger, but not the risk of wheezing for children over 2 years of age.

CONCLUSIONS

This meta-analysis shows that early child care attendance is not significantly associated with the risk of asthma or wheeze in children 6 years of age or older.

Relationship between breastfeeding and asthma prevalence in young children exposed to adverse childhood experiences

OBJECTIVE

To investigate if duration of supplemental breastfeeding is associated with a lower asthma risk and whether adverse childhood experiences (ACEs) early in life influence this relationship in children ages 3 to 5 years.

METHODS

Data were from the 2011-2012 National Survey of Children's Health, a nationally representative cross-sectional survey. Modified Poisson regression models were used to estimate incident risk ratios (IRR) for lifetime and current asthma in young children aged 3 to 5 years (n = 15,642). We tested for effect measure modification using stratified analyses.

RESULTS

Exclusive breastfeeding for at least 6 months or supplemental breastfeeding for children ≥12 months significantly reduced the risk of lifetime asthma prevalence compared to never breastfed children (IRR 0.64; 95% CI: 0.46-0.88, p = 0.007; and IRR 0.68; 95% CI: 0.47-0.99, p = 0.044, respectively), adjusted for covariates. In stratified analyses, breastfeeding reduced the risk of lifetime asthma for children who experienced 1 ACE but not for children who experienced 2 or more ACEs.

CONCLUSION

Exclusive breastfeeding for at least 6 months, with and without supplementation, appears to prevent asthma or delay its onset. The protective effect of breastfeeding was attenuated among children who experienced more than 2 ACEs. The known harmful effects that ACEs have on children's health may outweigh the benefits of breastfeeding in reducing the risk of a child developing asthma. Understanding how specific time periods in a child's life may be most affected by exposure to early life adversities, along with the protective effect of breastfeeding against asthma, are important areas of further study.

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

BACKGROUND/OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Re-examining the association between residential exposure to magnetic fields from power lines and childhood asthma in the Danish National Birth Cohort

Background

A study reported an increased risk of asthma in children whose mothers were exposed to magnetic field (MF) levels above 0.2 μT during pregnancy. We re-examined this association using data from mothers and children in the Danish National Birth Cohort (DNBC).

Methods

This study included 92,676 singleton-born children and their mothers from the DNBC. MF exposure from power lines was estimated for all residences where the mothers lived during pregnancy and for all children from birth until the end of follow up. Exposure was categorized into 0 μT, 0.1 μT, and ≥ 0.2 μT for analysis. Definitive and possible asthma cases were identified using data from three independent data sources: 1) mothers’ reports, 2) a national hospitalization register, 3) a national prescription drug register. We calculated hazard ratios (HR) and 95% confidence intervals (CI) for the association between the highest level of exposure during pregnancy and asthma in children, adjusting for several potential confounding factors. We also examined the sensitivity of the risk estimates to changes in exposure and outcome definitions.

Results

No differences or trends in the risk of asthma development were detected between children with different levels of MF exposure regardless of the asthma case definition or outcome data source. For definitive cases, the HR (95% CI) for those with any exposure was 0.72 (0.27–1.92), and it was 0.41 (0.06–2.92) for those exposed to ≥ 0.2 μT. Adjustments for confounding and variations in the exposure definition did not appreciably alter the results.

Conclusion

We did not find evidence that residential exposure to MF during pregnancy or early childhood increased the risk of childhood asthma. This interpretation is in line with the lack of an established biological mechanism directly linking MF exposure to asthma, but high exposure was very rare in this cohort.

Association of living in a farming environment with asthma incidence in Canadian children

OBJECTIVE

The objective of this population-based 14-year follow-up study was to examine the effect of living in a farm environment on asthma incidence in children.

METHODS

A total of 10,941 children of ages 0 to 11 years who were free of asthma and wheeze at the baseline (1994-1995) in the National Longitudinal Survey of Children and Youth were considered in the study. Children's living environment was classified, based on interviewer's observation, into three categories: non-rural, rural non-farming, and farming. An incidence of asthma was obtained from health-professional diagnosed asthma reported either by the person most knowledgeable for children under 15 years or by the children themselves if they were of ages 16 years and over.

RESULTS

The 14-year cumulative incidence of asthma among children living in farming environments was 10.18%, which was significantly lower than that observed for children living in rural non-farming (13.12%) and non-rural environments (16.50%). After adjusting for age group, number of older siblings, allergy, parental history of asthma, dwelling in need of repairs and SES index, a dose-response relationship was observed with children living in rural non-farming and farming environments having significantly reduced risk of asthma [hazard ratio (HR): 0.77; 95% confidence interval (CI): (0.60, 1.00); p = 0.047 and HR: 0.56; 95% CI: (0.41,0.77); p < 0.001] in comparison to those living in non-rural environments.

CONCLUSION

This cohort study provides further evidence that living in a farming environment during childhood is protective of asthma incidence in adolescence and adulthood and this finding provides further support for the hygiene hypothesis.

Routinely sleeping away from home and the association with child asthma readmission

The increased prevalence of transitions between households may have implications for child asthma morbidity. We, therefore, sought to enumerate the prevalence of regularly spending nights sleeping away from home among children admitted to the hospital for asthma and to examine the relationship of nights away to asthma-related readmission. This was a population-based, prospective cohort of 774 children, aged 1-16 years, who were admitted with asthma or bronchodilator-responsive wheezing and enrolled in the Greater Cincinnati Asthma Risks Study. The study took place at Cincinnati Children's Hospital Medical Center, an urban, academic children's hospital in the Midwest. The primary exposure was regularly spending nights away from home. Selected covariates included caregiver marital status, shift work, child's race, income, psychological distress, and running out of/not having medications on hand. The primary outcome was asthma-related readmission within 12 months. A total of 19 % were readmitted within 12 months. The 33 % of children that spent ≥1 night away from home per week were significantly more likely to be readmitted than those who spent no nights away (25 % vs. 16 %, p = 0.002). Spending nights away from home [adjusted relative risk (aRR) 1.5, 95 % confidence interval (CI) 1.2-2.0] and lower income (aRR 2.6, 95 % CI 1.1-6.4) were the strongest independent predictors of readmission after adjusting for child age, gender, and race, and caregiver marital status, shift work, risk of psychological distress, and running out of meds. Increased awareness of the multiple settings in which children with asthma live may help shape more comprehensive approaches to asthma care.

The first 2-year home environment in relation to the new onset and remission of asthmatic and allergic symptoms in 4246 preschool children

The home environment can influence childhood allergies and respiratory health but there is little information on associations between early life exposure at home and new onset and remission of the asthmatic or allergic symptoms in preschool children. A questionnaire survey was performed in a random cluster sample of 4246 preschool children in Urumqi, China. Information on the home environment (perceptions of odors and indicators of pollution sources) and children's health (wheeze, rhinitis and eczema) was collected for the first 2 years of life and the last year (before answering the questionnaire) from one of the parents or another guardian of the child. Associations between the home environment the first 2 years of life and new onset and remission of childhood symptoms were analyzed by multiple logistic regression. Home environment factors reported for the first 2 years of life were consistently positively associated with new onset of symptoms and negatively associated with remission of symptoms. Visible mold (OR 1.46, 95% CI 1.12-1.90), moldy odor (OR 2.15, 95% CI 1.45-3.18), air dryness (OR 1.31, 95% CI 1.08-1.59), stuffy odor (OR 1.25, 95% CI 1.01-1.54) and parental smoking (OR 1.36, 95% CI 1.13-1.65) were associated with new onset of symptoms. These factors were negatively associated with the remission of symptoms. In conclusion, mold contamination at home (moldy odor/visible mold), poor indoor air quality (stuffy odor, air dryness) and exposure to environmental tobacco smoke (ETS) in the first 2 years of life can increase the incidence of asthmatic and allergic symptoms and decrease the remission from these symptoms in preschool children.

Effect of Maternal Electroacupuncture on Perinatal Nicotine Exposure-Induced Lung Phenotype in Offspring

INTRODUCTION

Pregnant women exposed to tobacco smoke predispose the offspring to many adverse consequences including an altered lung development and function. There is no effective therapeutic intervention to block the effects of smoke exposure on the developing lung. Clinical and animal studies demonstrate that acupuncture can modulate a variety of pathophysiological processes, including those involving the respiratory system; however, whether acupuncture affects the lung damage caused by perinatal smoke exposure is not known.

METHODS

To determine the effect of acupuncture on perinatal nicotine exposure on the developing lung, pregnant rat dams were administered (1) saline, (2) nicotine, or (3) nicotine + electroacupuncture (EA). Nicotine was administered (1 mg/kg subcutaneously) once a day and EA was applied to both "Zusanli" (ST 36) points. Both interventions were administered from gestational day 6 to postnatal day 21 (PND21), following which pups were sacrificed. Lungs, blood, and brain were collected to examine markers of lung injury, repair, and hypothalamic pituitary adrenal (HPA) axis.

RESULTS

Concomitant EA application blocked nicotine-induced changes in lung morphology, lung peroxisome proliferator-activated receptor γ and wingless-int signaling, two key lung developmental signaling pathways, hypothalamic pituitary adrenal axis (hypothalamic corticotropic releasing hormone and lung glucocorticoid receptor levels), and plasma β-endorphin levels.

CONCLUSIONS

Electroacupuncture blocks the nicotine-induced changes in lung developmental signaling pathways and the resultant myogenic lung phenotype, known to be present in the affected offspring. We conclude that EA is a promising novel intervention against the smoke exposed lung damage to the developing lung.

Postpartum depression, a direct and mediating risk factor for preschool wheeze in girls

BACKGROUND

Postpartum depression affects over 1 in 10 child-bearing women. A growing body of evidence links maternal distress during the key developmental stages of infants with poor health outcomes, including wheeze and asthma.

OBJECTIVE

We sought to investigate whether postpartum depression had an independent association with the development of wheeze in preschool-aged children. A second a priori objective was to ascertain whether postpartum depression functioned as a mediating factor for associations between wheeze, and prenatal distress and nutrition.

METHODS

Data from the Community Perinatal Care Trial on maternal postpartum depression (Edinburgh Postnatal Depression Scale), the dependent variable, wheeze at age 3, and possible confounding factors were obtained for 791 women and their children in Calgary, Canada. Adjusted gender-specific logistic regression analyses were performed to test the association between postpartum depression and child wheeze, which was independent of maternal distress and vitamin use during pregnancy, pre/postnatal smoking, preterm birth, exclusive breastfeeding duration, daycare attendance, and maternal education. The potential mediating effects of postpartum depression were investigated in a path analysis.

RESULTS

Wheeze at age 3 was almost 5 times more likely in girls of mothers who experienced postpartum depression. Results from a path analysis suggested that postpartum depression has a direct effect on wheeze (beta-coefficient=0.135, P < 0.05), and also mediates the effects of prenatal distress and vitamin use on wheeze in preschool girls. In boys, only prenatal smoking was a statistically significant predictor of wheeze, mainly through the effects of postnatal smoking.

CONCLUSIONS & CLINICAL RELEVANCE

Postpartum depression may be a risk factor for preschool wheeze among girls in a low risk population, directly and indirectly through prenatal distress and vitamin use. Interventions which target postpartum depression and promote a healthy pregnancy may also reduce the risk of wheeze in children.

Relative Importance and Additive Effects of Maternal and Infant Risk Factors on Childhood Asthma

Background

Environmental exposures that occur in utero and during early life may contribute to the development of childhood asthma through alteration of the human microbiome. The objectives of this study were to estimate the cumulative effect and relative importance of environmental exposures on the risk of childhood asthma.

Methods

We conducted a population-based birth cohort study of mother-child dyads who were born between 1995 and 2003 and were continuously enrolled in the PRIMA (Prevention ofRSV: Impact onMorbidity andAsthma) cohort. The individual and cumulative impact of maternal urinary tract infections (UTI) during pregnancy, maternal colonization with group B streptococcus (GBS), mode of delivery, infant antibiotic use, and older siblings at home, on the risk of childhood asthma were estimated using logistic regression. Dose-response effect on childhood asthma risk was assessed for continuous risk factors: number of maternal UTIs during pregnancy, courses of infant antibiotics, and number of older siblings at home. We further assessed and compared the relative importance of these exposures on the asthma risk. In a subgroup of children for whom maternal antibiotic use during pregnancy information was available, the effect of maternal antibiotic use on the risk of childhood asthma was estimated.

Results

Among 136,098 singleton birth infants, 13.29% developed asthma. In both univariate and adjusted analyses, maternal UTI during pregnancy (odds ratio [OR] 1.2, 95% confidence interval [CI] 1.18, 1.25; adjusted OR [AOR] 1.04, 95%CI 1.02, 1.07 for every additional UTI) and infant antibiotic use (OR 1.21, 95%CI 1.20, 1.22; AOR 1.16, 95%CI 1.15, 1.17 for every additional course) were associated with an increased risk of childhood asthma, while having older siblings at home (OR 0.92, 95%CI 0.91, 0.93; AOR 0.85, 95%CI 0.84, 0.87 for each additional sibling) was associated with a decreased risk of childhood asthma, in a dose-dependent manner. Compared with vaginal delivery, C-section delivery increased odds of childhood asthma by 34% (OR 1.34, 95%CI 1.29, 1.39) in the univariate analysis and 11% after adjusting for other environmental exposures and covariates (AOR 1.11, 95%CI 1.06, 1.15). Maternal GBS was associated with a significant increased risk of childhood asthma in the univariate analysis (OR 1.27, 95%CI 1.19, 1.35), but not in the adjusted analysis (AOR 1.03, 95%CI 0.96, 1.10). In the subgroup analysis of children whose maternal antibiotic use information was available, maternal antibiotic use was associated with an increased risk of childhood asthma in a similar dose-dependent manner in the univariate and adjusted analyses (OR 1.13, 95%CI 1.12, 1.15; AOR 1.06, 95%CI 1.05, 1.08 for every additional course). Compared with infants with the lowest number of exposures (no UTI during pregnancy, vaginal delivery, at least five older siblings at home, no antibiotics during infancy), infants with the highest number of exposures (at least three UTIs during pregnancy, C-section delivery, no older siblings, eight or more courses of antibiotics during infancy) had a 7.77 fold increased odds of developing asthma (AOR: 7.77, 95%CI: 6.25, 9.65). Lastly, infant antibiotic use had the greatest impact on asthma risk compared with maternal UTI during pregnancy, mode of delivery and having older siblings at home.

Conclusion

Early-life exposures, maternal UTI during pregnancy (maternal antibiotic use), mode of delivery, infant antibiotic use, and having older siblings at home, are associated with an increased risk of childhood asthma in a cumulative manner, and for those continuous variables, a dose-dependent relationship. Compared with in utero exposures, exposures occurring during infancy have a greater impact on the risk of developing childhood asthma.

Prevalence and risk factors for atopic disease in a population of preschool children in Rome: Challenges to early intervention

BACKGROUND

Allergic diseases are complex identities determined by an interplay of genetic and environmental factors, resulting in the clinical manifestation of the disease. So far in Italy, updated data about the prevalence and risk factors of respiratory and allergic diseases in preschool children are not available.

METHODS

Children aged 3-5 years, attending four different nursery schools in an urban district of the city of Rome. A standardized questionnaire developed under the SIDRIA-2 protocol was administered to the parents of the children for the assessment of the potential risk factors and the outcomes.

RESULTS

A total of 494 children were enrolled in the study; 289 of them (60.3%) performed a skin prick test (SPT). In the 12 months preceding the interviews, 15% of children experienced at least one episode of wheezing, 5.5% of allergic rhinitis, 11% of children had a doctor diagnosis of asthma, 12% of children who underwent the SPT were positive to at least one of the tested allergens, being diagnosed as atopic. The univariate analysis for the health outcomes of the study shows that asthma was positively associated with daycare attendance, mother's history of atopy, siblings' history of atopy, recurrent siblings' bronchitis, and dermatitis. Atopy was positively associated with mother's history of atopy and dermatitis, whereas there is a borderline protective association with recurrent siblings' bronchitis.

CONCLUSIONS

This study represents a first comprehensive epidemiological evaluation of prevalence of respiratory and allergic diseases in children aged 3-5 years in the city of Rome and an updating of the evolution of allergic diseases.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Reported associations between asthma and acute lymphoblastic leukemia: insights from a hybrid simulation study

Numerous studies have reported a protective association between asthma and acute lymphoblastic leukemia (ALL), but the causal structure of this association remains unclear. We present a hybrid simulation to examine the compatibility of this association with uncontrolled confounding by infection or another unmeasured factor. We generated a synthetic cohort using inputs on the interrelations of asthma, ALL, infections, and other suggested risk factors from the literature and the Danish National Birth Cohort. We computed odds ratios (ORs) between asthma and ALL in the synthetic cohort with and without adjustment for infections and other (including unmeasured) confounders. Only if infection was an extremely strong risk factor for asthma (OR of 10) and an extremely strong protective factor against ALL (OR of 0.1) was the asthma-ALL association compatible with the literature (OR of 0.78). Similarly, strong uncontrolled confounding by an unmeasured factor could downwardly bias the asthma-ALL association, but not enough to replicate findings in the literature. This investigation illustrates that the reported protective association between asthma and ALL is unlikely to be entirely due to uncontrolled confounding by infections or an unmeasured confounder alone. Simulation can be used to advance our understanding of risk factors for rare outcomes as demonstrated by this study.

Role of Environmental Factors in the Development of Pediatric Eosinophilic Esophagitis

BACKGROUND

Despite accumulating data on the pathogenesis of eosinophilic esophagitis, not much is known about risk factors for the development of the disease. The role of factors such as smoking, breastfeeding, early antibiotic exposure and other factors that have been associated with other allergic diseases has not been well studied in children with eosinophilic esophagitis.

AIM

To explore the role of environmental and medication exposures in the development of pediatric eosinophilic esophagitis.

METHODS

We conducted a cross-sectional case-control study, utilizing a parent and child questionnaire and medical chart review. Urine cotinine levels, measured by high-performance liquid chromatography, were obtained as objective evidence for smoking exposure.

RESULTS

One hundred and two children with eosinophilic esophagitis and 167 controls were recruited. The controls were mainly diagnosed with functional gastrointestinal disorders (33%) and gastroesophageal reflux disease (29%). Food allergy, specifically for peanuts and tree nuts, and allergy to pollen, tree, and grass were significantly higher among eosinophilic esophagitis children. Smoking exposure, both primary and secondary, was not associated with pediatric eosinophilic esophagitis when compared to controls (odds ratio 0.96, 95% confidence interval 0.58-1.59). Furthermore, early smoking exposure in the first year of life was higher among controls. Common accepted risk factors for allergy and atopy, such as breastfeeding practices, antibiotics exposure, animals' exposure, and others, were not found to be associated with eosinophilic esophagitis in our study.

CONCLUSION

Common risk factors in other allergic and atopic conditions were not found to be associated with eosinophilic esophagitis.

Association between asthma and body mass index and socioeconomic status: A cross-sectional study on 849,659 adolescents

BACKGROUND AND OBJECTIVE

Asthma is associated with body mass index (BMI), but its association with socioeconomic status (SES) is controversial. The combined effect of SES and BMI on asthma prevalence is undetermined.

METHODS

Seventeen-year-old pre-recruits to the Israeli Defense Forces underwent routine physical examinations. SES was determined according to established criteria based on place of residence. The study population was divided according to classic weight groups and three SES groups (low, medium and high). Univariable and multivariable logistic regression models were applied to assess odds ratios (OR) of BMI and SES groups for asthma prevalence. The combined effect of BMI and SES was also calculated.

RESULTS

The 849,659 subjects included 480,993 males (9.5% asthma prevalence) and 368,666 females (6.7% asthma prevalence). Increased BMI were associated with increased OR for asthma in females (1.44, 95% CI 1.36-1.52 for obese vs normal weight). Males had a J-shaped curve (OR 1.24 95% CI 1.2-1.29 for obese, 1.12, 95% CI 1.08-1.16 for underweight, both vs normal weight). OR adjusted to SES did not change significantly. All SES groups produced a linear curve (1.59 95% CI 1.53-1.66 for females and 1.79 95% CI 1.74-1.84 for males). Adjustment of SES to BMI produced no significant change in OR. When all groups were compared with the normal weight/lower SES group, the highest OR was for the obese/higher SES group (2.32 95% CI 2.05-2.64 for females and 1.99 95% CI 1.83-2.13 for males).

CONCLUSIONS

Both BMI and SES are co-independently associated with asthma in adolescent males and females.

Siblings, asthma, rhinoconjunctivitis and eczema: a worldwide perspective from the International Study of Asthma and Allergies in Childhood

Background

Associations of larger families with lower prevalences of hay fever, eczema and objective markers of allergic sensitization have been found fairly consistently in affluent countries, but little is known about these relationships in less affluent countries.

Methods

Questionnaire data for 210 200 children aged 6–7 years from 31 countries, and 337 226 children aged 13–14 years from 52 countries, were collected by Phase Three of the International Study of Asthma and Allergies in Childhood (ISAAC). Associations of disease symptoms and labels of asthma, rhinoconjunctivitis and eczema were analysed by numbers of total, older and younger siblings, using mixed (multi-level) logistic regression models to adjust for individual covariates and at the centre level for region, language and national affluence.

Results

In both age groups, inverse trends (P < 0.0001) were observed for reported ‘hay fever ever’ and ‘eczema ever’ with increasing numbers of total siblings, and more specifically older siblings. These inverse associations were significantly (P < 0.005) stronger in more affluent countries. In contrast, symptoms of severe asthma and severe eczema were positively associated (P < 0.0001) with total sibship size in both age groups. These associations with disease severity were largely independent of position within the sibship and national GNI per capita.

Conclusions

These global findings on sibship size and childhood asthma, rhinoconjunctivitis and eczema suggest at least two distinct trends. Inverse associations with older siblings (observations which prompted the ‘hygiene hypothesis’ for allergic disease) are mainly a phenomenon of more affluent countries, whereas greater severity of symptoms in larger families is globally more widespread.

Fetal lung and placental methylation is associated with in utero nicotine exposure

In utero smoke exposure has been shown to have detrimental effects on lung function and to be associated with persistent wheezing and asthma in children. One potential mechanism of IUS effects could be alterations in DNA methylation, which may have life-long implications. The goal of this study was to examine the association between DNA methylation and nicotine exposure in fetal lung and placental tissue in early development; nicotine exposure in this analysis represents a likely surrogate for in-utero smoke. We performed an epigenome-wide analysis of DNA methylation in fetal lung tissue (n = 85, 41 smoke exposed (48%), 44 controls) and the corresponding placental tissue samples (n = 80, 39 smoke exposed (49%), 41 controls) using the Illumina HumanMethylation450 BeadChip array. Differential methylation analyses were conducted to evaluate the variation associated with nicotine exposure. The most significant CpG sites in the fetal lung analysis mapped to the PKP3 (P = 2.94 × 10(-03)), ANKRD33B (P = 3.12 × 10(-03)), CNTD2 (P = 4.9 × 10(-03)) and DPP10 (P = 5.43 × 10(-03)) genes. In the placental methylome, the most significant CpG sites mapped to the GTF2H2C and GTF2H2D genes (P = 2.87 × 10(-06) - 3.48 × 10(-05)). One hundred and one unique CpG sites with P-values < 0.05 were concordant between lung and placental tissue analyses. Gene Set Enrichment Analysis demonstrated enrichment of specific disorders, such as asthma and immune disorders. Our findings demonstrate an association between in utero nicotine exposure and variable DNA methylation in fetal lung and placental tissues, suggesting a role for DNA methylation variation in the fetal origins of chronic diseases.

Neonatal urinary tract infection may increase the risk of childhood asthma

The aim of this population-based retrospective cohort study was to investigate the onset of urinary tract infection in newborns and the associated risks of childhood asthma. Children with neonatal UTI (n = 3,312) and randomly selected controls (n = 13,243) were enrolled for our analysis. We calculated the follow-up person-years for each participant from the index date until the diagnosis of asthma, the end of 2008, or withdrawal from the insurance system (because of death or loss to follow-up). Furthermore, we compared the risk of asthma between non-UTI and UTI cohorts by using Cox proportional hazards model analysis, the adjusted hazard ratio (aHR), and a 95 % confidence interval (95 % CI). The overall asthma incidence rate was found to be 1.53-fold significantly higher in the UTI cohort than in the non-UTI cohort (70.3 vs 45.8 per 1000 person-years). After we adjusted for potential risk factors, the overall risk of asthma remained higher in the UTI cohort (aHR = 1.47, 95 % CI = 1.35-1.59). The incidence rate was higher in boys than in girls. Overall, patients suffering from UTI may have a greater risk of developing asthma than patients without UTI. This nationwide retrospective cohort study demonstrates that neonatal UTI may increase the risk of childhood asthma.

Risk of Asthma in Late Preterm Infants: A Propensity Score Approach

BACKGROUND

The risk of asthma, specifically in former late preterm infants, has not been well defined. Covariate imbalance and lack of controlling for this has led to inconsistent results in prior studies.

OBJECTIVE

The objective of this study was to determine the risk of asthma in former late preterm infants using a propensity score approach.

METHODS

The study was a population-based birth cohort study. Study subjects were all children born in Rochester, Minn, between 1976 and 1982. Asthma status during the first 7 years of life was assessed by applying predetermined criteria. The propensity score was formulated using 15 covariates by fitting a logistic regression model for late preterm birth versus term birth. We applied the propensity score method to match late preterm infants (34 0/7 to 36 6/7 weeks of gestation) to term infants (37 0/7 to 40 6/7 weeks of gestation) within a caliper of 0.2 standard deviation of logit of propensity score.

RESULTS

Of the eligible 7040 infants, 5915 children had complete data. Before propensity score matching, late preterm infants had a higher risk of asthma (20 of 262, 7.6%) compared with full-term infants (272 of 5653, 4.8%) (P = .039). There was significant covariate imbalance between comparison groups. After matching with propensity scores, we found that former late preterm infants had a similar risk of asthma to the matched full-term infants (6.6% vs 7.7%, respectively, P = .61), and the result was consistent with covariate-adjustment Cox regression models controlling for significant covariates (P = .57).

CONCLUSION

A late preterm birth history is not independently associated with childhood asthma, as the reported risk of asthma among former late preterm infants appears to be due to covariate imbalance.

Maternal socioeconomic status and the risk of asthma among offspring

BACKGROUND

To evaluate the association between maternal socioeconomic status (SES) during pregnancy and asthma among offspring.

METHODS

A retrospective observational hospital-based birth cohort study in a university-based Obstetrics and Gynecology department in Finland. A total of 40 118 women with singleton live births between 1989 and 2007 were linked with data from the register for asthma medication for their offspring (n = 2518). Pregnancy and maternal SES factors were recorded during pregnancy and labor. SES was categorized thus: upper white-collar workers (highest SES), lower white-collar workers, blue-collar workers, others (lowest SES) and cases with missing information. Logistic regression analysis was used to determine the association between maternal SES and childhood asthma.

RESULTS

We found no convincing evidence of a direct association between maternal SES and childhood asthma. Parental smoking was the clearest factor affecting asthma among children of lower white-collar workers. Differences in pregnancy and delivery characteristics were observed between the SES groups.

CONCLUSIONS

Maternal socioeconomic status had no significant direct impact on the prevalence of asthma in this Finnish birth cohort. Finnish public health services appeared to offer equal quality services independently of SES.

TRIAL REGISTRATION

The study is registered in Kuopio University Hospital register (TUTKI): ID 5302448 .

Birth weight and childhood wheezing disorders: a systematic review and meta-analysis

BACKGROUND

Previous observational studies have claimed that birth weight and childhood wheezing disorders are associated although the results remained inconsistent. One systematic review and two systematic reviews that included meta-analyses reported inconsistent results. We aimed to conduct a systematic review and meta-analysis to investigate this.

METHODS

An online search of published papers linking childhood asthma and wheezing disorders with birth weight up to February 2014 was carried out using EMBASE and Medline medical research databases. Summary ORs were estimated using random-effects models. Subgroup meta-analyses were performed to assess the robustness of risk associations and between-study heterogeneity.

RESULTS

A total of 37 studies comprising 1,71, 737 participants were included in our meta-analysis. The unadjusted summary ORs for risk of childhood wheezing disorders associated with low birth weight (<2.5 kg) were 1.60 (95% CI 1.39 to 1.85, p<0.001) and 1.37 (95% CI 1.05 to 1.79, p=0.02) when compared with ≥2.5 and 2.5-4.0 kg birthweight groups, respectively. The overall summary OR for high birth weight (>4 kg) as compared to the 2.5-4.0 kg birthweight group was 1.02 (95% CI 0.99 to 1.04, p=0.13). There was substantial heterogeneity in the unadjusted low birth weight risk estimates which was not accounted for by predefined study characteristics. There was no significant heterogeneity in the high birth weight risk estimates. There was some evidence of funnel plot asymmetry and small study effects in the low birth weight (2.5 vs ≥2.5 kg and <2.5 vs 2.5-4 kg) OR estimates.

CONCLUSIONS

Our results suggest that low birth (<2.5 kg) is an independent risk factor for wheezing disorders during childhood and adolescence although there was substantial heterogeneity among the risk estimates. However, we found no significant association of high birth weight with wheezing disorders.

A systematic review of associations between environmental exposures and development of asthma in children aged up to 9 years

OBJECTIVES

Childhood asthma is a complex condition where many environmental factors are implicated in causation. The aim of this study was to complete a systematic review of the literature describing associations between environmental exposures and the development of asthma in young children.

SETTING

A systematic review of the literature up to November 2013 was conducted using key words agreed by the research team. Abstracts were screened and potentially eligible papers reviewed. Papers describing associations between exposures and exacerbation of pre-existing asthma were not included. Papers were placed into the following predefined categories: secondhand smoke (SHS), inhaled chemicals, damp housing/mould, inhaled allergens, air pollution, domestic combustion, dietary exposures, respiratory virus infection and medications.

PARTICIPANTS

Children aged up to 9 years.

PRIMARY OUTCOMES

Diagnosed asthma and wheeze.

RESULTS

14,691 abstracts were identified, 207 papers reviewed and 135 included in the present review of which 15 were systematic reviews, 6 were meta-analyses and 14 were intervention studies. There was consistent evidence linking exposures to SHS, inhaled chemicals, mould, ambient air pollutants, some deficiencies in maternal diet and respiratory viruses to an increased risk for asthma (OR typically increased by 1.5-2.0). There was less consistent evidence linking exposures to pets, breast feeding and infant dietary exposures to asthma risk, and although there were consistent associations between exposures to antibiotics and paracetamol in early life, these associations might reflect reverse causation. There was good evidence that exposures to house dust mites (in isolation) was not associated with asthma risk. Evidence from observational and intervention studies suggest that interactions between exposures were important to asthma causation, where the effect size was typically 1.5-3.0.

CONCLUSIONS

There are many publications reporting associations between environmental exposures and modest changes in risk for asthma in young children, and this review highlights the complex interactions between exposures that further increase risk.

The interaction between mother and fetus and the development of allergic asthma

The rising prevalence of asthma and atopic disease in industrialized countries in the last 50 years has raised important questions about how and why the disease develops in susceptible populations. Most asthma begins in childhood in association with allergic sensitization and the development of a TH2 phenotype. It is recognized that asthma arises in the context of a complex interaction between genetic factors and the evolving immune system of the infant and the environment to which it is exposed, which now includes its in utero exposure. Early life exposures that lead to allergen sensitization and airway damage, especially in the form of viral respiratory tract infections, may lead to disease induction that commence the process that leads in some to asthma. Asthma models and early life observations suggest that repeated exposure to allergens and viral infection perpetuate a state of chronic airway inflammation leading to a maladaptive innate immune response that fails to resolve, characterized by chronic airway inflammation, airway remodeling and airway hyperresponsiveness. This article will concentrate on the development of asthma in the context of early life and maternal influences, including the effect of asthma on both the fetus and the mother.