Risk factors for current wheezing and its phenotypes among elementary school children

Comparing the Diagnostic Accuracy of Measures of Maternal Diet During Pregnancy for Offspring Allergy Outcomes: The Healthy Start Study

BACKGROUND

Allergic diseases in children are increasing. Although maternal diet quality in pregnancy may be protective, it is unclear which measure of maternal diet best predicts offspring diseases.

OBJECTIVE

To examine the associations between multiple diet measures and allergy outcomes, and to compare the diagnostic accuracy of the measures for the prediction of allergy outcomes.

METHODS

Maternal diet during pregnancy was measured using a validated instrument, and scored using 5 measures: the maternal diet index (MDI), Healthy Eating Index, total diet diversity, healthy diet diversity, and unhealthy diet diversity. Unadjusted and adjusted logistic regression models assessed associations between maternal diet measures and offspring allergy outcomes up to age 4 years. The diagnostic accuracy of the diet measures was compared.

RESULTS

There were significant associations between MDI (odds ratio [OR], 0.78; 95% CI, 0.70-0.87), Healthy Eating Index (OR, 0.98; 95% CI, 0.97-0.99), and healthy diet diversity scores (OR, 0.91; 95% CI, 0.85-0.98) during pregnancy and the primary combined outcome "any allergy excluding wheeze" in children up to age 4 years. Neither maternal total diet diversity (OR, 0.99; 95% CI, 0.95-1.03) nor unhealthy diet diversity scores (OR, 1.05; 95% CI, 0.98-1.13) were associated with the "any allergy excluding wheeze" outcome. For all outcomes studied, except for food allergy, there was a significant difference in the diagnostic accuracy between the 5 measures of maternal diet. The area under the curve for MDI was highest for every disease outcome, although not always significantly higher.

CONCLUSIONS

Better quality and higher diversity of a woman's diet during pregnancy, measured in various ways, is associated with offspring allergy outcomes, with healthy foods associated with decreased risk, and unhealthy foods associated with a higher risk. The MDI, which appropriately weighted both healthy and unhealthy foods, best predicted childhood allergic disease.

Early-life residential exposure to moisture damage is associated with persistent wheezing in a Finnish birth cohort

BACKGROUND AND AIMS

Moisture damage increases the risk for respiratory disorders in childhood. Our aim was to determine whether early age residential exposure to inspector-observed moisture damage or mold is associated with different wheezing phenotypes later in childhood.

METHODS

Building inspections were performed by civil engineers, in a standardized manner, in the children's homes-mostly single family and row houses (N = 344)-in the first year of life. The children were followed up with repeated questionnaires until the age of 6 years and wheezing phenotypes-never/infrequent, transient, intermediate, late onset, and persistent-were defined using latent class analyses. The multinomial logistic regression model was used for statistical analysis.

RESULTS

A total of 63% (n = 218) had infrequent or no wheeze, 23% (n = 80) had transient and 9.6% (n = 21) had a persistent wheeze. Due to the low prevalence, results for intermediate (3.8%, n = 13) and late-onset wheeze (3.5%, n = 12) were not further evaluated. Most consistent associations were observed with the persistent wheeze phenotype with an adjusted odds ratio (95% confidence intervals) 2.04 (0.67-6.18) for minor moisture damage with or without mold spots (present in 23.8% of homes) and 3.68 (1.04-13.05) for major damage or any moisture damage with visible mold in a child's main living areas (present in 13.4% of homes). Early-age moisture damage or mold in the kitchen was associated with transient wheezing.

CONCLUSION

At an early age, residential exposure to moisture damage or mold, can be dose-dependently associated especially with persistent wheezing phenotype later in childhood.

Risk factors for current wheeze among school children (6–7 and 13–14 years old) in Khuzestan, Iran

Objectives

In recent years, there has been a clear trend of increasing allergic diseases especially in children, and developing countries are no exception. Thepresentstudy sought to determine the risk factors associated with wheezing among school children aged 6–7 and 13–14 years living in Khuzestan Province, Iran.

Study design

Cross-sectional.

Methods

Data for this cross-sectional study is the history of wheeze in the last 12 months. The participants included 6-7- and 13-14-year-old girls and boys studying in urban schools in Khuzestan Province in 2019. We collected the data using the multi stage sampling technique as suggested in the International Study of Asthma and Allergies in Childhood (ISAAC). The research reviewed the literature and consulted experts to collect the risk factors for demographic and clinical information, environmental exposure and lifestyle.

Results

Eight thousand questionnaires were handed out to both age groups, of which 7344 were completed. Two hundred ninety-nine (4.1 %) of the participants had current wheeze. Three-point four percent (124 individuals) in the 6–7 year age group and 4.8 % in the 13–14-year-old age group had current wheezing. The results of the logistic regression model suggest that the most significant risk factors associated with the chance of developing current wheeze in the both age groups are: being male (OR: 1.46, 95 % CI: 1.12–1.88), being from employed mother families (OR: 1.50, 95 %, CI:1.05–2.08), property ownership (OR:1.36, 95 %, CI:1.04–1.79) bugs in the property (OR: 1.29, 95 %, CI:0.99–1.70) mold in the property (OR: 1.75, 95 %, CI:1.12–2.76), pet(s) in the student's bedroom (OR: 1.75, 95 %, CI: 0.97–3.14), a family history of asthma and allergic diseases (OR: 2.20, 95 %, CI: 1.69–2.87), tobacco smoke exposures in the property (OR: 1.43, 95 %, CI:1.04–1.96), having allergic rhinitis (OR: 7.86, 95 % CI: 5.89–10.50) and eczema (OR: 3.85, 95 % CI: 2.10–7.08).

Conclusions

Families are suggested to adopt strategies to reduce exposure to outdoor air pollutants and contain indoor allergens. More studies are necessary to further explore the effects of modifying and changing these risk factors.

•

3.4 % in the 6–7 year age group and 4.8 % in the 13–14 year age group had current wheezing.

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In both age groups, current wheeze is more common in boys than girls.

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Mold in the home, pet in the bedroom and tobacco smoke exposures are the most important risk factors for current wheeze.

Incidence and timing of offspring asthma, wheeze, allergic rhinitis, atopic dermatitis, and food allergy and association with maternal history of asthma and allergic rhinitis

Background

Studying the developmental precursors of allergy may help explain the mechanisms (or etiology) of allergic disease. We studied childhood respiratory and allergic diseases in a pre-birth cohort from the United States.

Objective

We assessed the associations between maternal history of asthma and the development of respiratory and allergic diseases in offspring. We also assessed associations with maternal history of allergic rhinitis.

Methods

Maternal history of asthma and allergic rhinitis was self-reported during early pregnancy. Offspring respiratory and allergy information was obtained from electronic medical records. Adjusted Cox proportional hazard models assessed the associations between maternal history of asthma and development of respiratory and allergic diseases in the offspring up to 8 years. A similar approach was used for maternal history of allergic rhinitis.

Results

Children born to women with a history of asthma had a 77% greater risk of developing asthma, a 45% greater risk of atopic dermatitis/eczema, and a 65% greater risk of wheeze (all p < 0.01), but no significantly increased risk of allergic rhinitis or food allergies, compared to children born to women with no history of asthma. Maternal history of allergic rhinitis was not associated with any child allergy outcome, and maternal history of both asthma and allergic rhinitis was associated with child atopic dermatitis/eczema only.

Conclusions

Maternal history of asthma was significantly associated with offspring respiratory and allergic diagnoses. The association between maternal history of asthma and offspring asthma and atopic dermatitis is a novel finding. Our findings may guide physicians who counsel families with a history of maternal asthma and allergic rhinitis about their child's risk of developing respiratory and allergic diseases.

Risk factors for atopic and nonatopic asthma in Puerto Rican children

BACKGROUND

Little is known about the risk factors for atopic and nonatopic asthma among children in Puerto Rico. We aimed to identify modifiable risk factors for atopic and nonatopic asthma in this vulnerable population.

METHODS

Case-control study of children with (n = 305) and without (n = 327) asthma in San Juan (Puerto Rico). Asthma was defined as physician-diagnosed asthma and wheeze in the previous year. Atopic asthma (n = 210) was defined as asthma and greater than or equal to one positive IgE to aero-allergens. Nonatopic asthma (n = 95) was defined as asthma and no positive IgE to the allergens tested. Logistic regression was used for the multivariable analysis of atopic and nonatopic asthma.

RESULTS

In a multivariable analysis, body mass index (BMI) z score, prematurity, parental asthma, lifetime exposure to gun violence, and having a bird in the child's home were associated with increased odds of atopic asthma, while each one-point increment in a dietary score (range: -2 [least healthy diet] to +2 [healthiest diet]) was associated with 37% reduced odds of atopic asthma (95% confidence interval [CI] = 0.48-0.81; P < .01). In a separate multivariable analysis, parental asthma, early-life second-hand smoke (SHS) exposure, and daycare attendance in the first year of life were significantly associated with increased odds of nonatopic asthma, while each one-point increment in the dietary score was associated with 42% reduced odds of nonatopic asthma (95% CI = 0.45-0.76; P < .01).

CONCLUSIONS

We have identified potentially modifiable risk factors for atopic asthma (eg, BMI and gun violence), nonatopic asthma (eg, early-life SHS and daycare attendance), or both (eg, an unhealthy diet) in Puerto Rican children.

Benefits of influenza vaccination on the associations between ambient air pollution and allergic respiratory diseases in children and adolescents: New insights from the Seven Northeastern Cities study in China

BACKGROUND

Little information exists on interaction effects between air pollution and influenza vaccination on allergic respiratory diseases. We conducted a large population-based study to evaluate the interaction effects between influenza vaccination and long-term exposure to ambient air pollution on allergic respiratory diseases in children and adolescents.

METHODS

A cross-sectional study was investigated during 2012-2013 in 94 schools from Seven Northeastern Cities (SNEC) in China. Questionnaires surveys were obtained from 56 137 children and adolescents aged 2-17 years. Influenza vaccination was defined as receipt of the influenza vaccine. We estimated air pollutants exposure [nitrogen dioxide (NO₂) and particulate matter with aerodynamic diameters ≤1 μm (PM₁), ≤2.5 μm (PM_2.5) and ≤10 μm (PM₁₀)] using machine learning methods. We employed two-level generalized linear mix effects model to examine interactive effects between influenza vaccination and air pollution exposure on allergic respiratory diseases (asthma, asthma-related symptoms and allergic rhinitis), after controlling for important covariates.

RESULTS

We found statistically significant interactions between influenza vaccination and air pollutants on allergic respiratory diseases and related symptoms (doctor-diagnosed asthma, current wheeze, wheeze, persistent phlegm and allergic rhinitis). The adjusted ORs for doctor-diagnosed asthma, current wheeze and allergic rhinitis among the unvaccinated group per interquartile range (IQR) increase in PM₁ and PM_2.5 were significantly higher than the corresponding ORs among the vaccinated group [For PM₁, doctor-diagnosed asthma: OR: 1.89 (95%CI: 1.57-2.27) vs 1.65 (95%CI: 1.36-2.00); current wheeze: OR: 1.50 (95%CI: 1.22-1.85) vs 1.10 (95%CI: 0.89-1.37); allergic rhinitis: OR: 1.38 (95%CI: 1.15-1.66) vs 1.21 (95%CI: 1.00-1.46). For PM_2.5, doctor-diagnosed asthma: OR: 1.81 (95%CI: 1.52-2.14) vs 1.57 (95%CI: 1.32-1.88); current wheeze: OR: 1.46 (95%CI: 1.21-1.76) vs 1.11 (95%CI: 0.91-1.35); allergic rhinitis: OR: 1.35 (95%CI: 1.14-1.60) vs 1.19 (95%CI: 1.00-1.42)]. The similar patterns were observed for wheeze and persistent phlegm. The corresponding p values for interactions were less than 0.05, respectively. We assessed the risks of PM₁-related and PM_2.5-related current wheeze were decreased by 26.67% (95%CI: 1.04%-45.66%) and 23.97% (95%CI: 0.21%-42.08%) respectively, which was attributable to influenza vaccination (both p for efficiency <0.05).

CONCLUSIONS

Influenza vaccination may play an important role in mitigating the detrimental effects of long-term exposure to ambient air pollution on childhood allergic respiratory diseases. Policy targeted at increasing influenza vaccination may yield co-benefits in terms of reduced allergic respiratory diseases.

Phenotypic and Molecular Characterization of Risk Loci Associated With Asthma and Lung Function

Purpose

Respiratory diseases have a highly multifactorial etiology where different mechanisms contribute to the individual's susceptibility. We conducted a deep characterization of loci associated with asthma and lung function by previous genome-wide association studies (GWAS).

Methods

Sixteen variants were selected from previous GWAS of childhood/adult asthma and pulmonary function tests. We conducted a phenome-wide association study of these loci in 4,083 traits assessed in the UK Biobank (n = 361,194 participants). Data from the Genotype-Tissue Expression (GTEx) project were used to conduct a transcriptomic analysis with respect to tissues relevant for asthma pathogenesis. A pediatric cohort assessed with the International Study of Asthma and Allergies in Children (ISAAC) Phase II tools was used to further explore the association of these variants with 116 traits related to asthma comorbidities.

Results

Our phenome-wide association studies (PheWAS) identified 206 phenotypic associations with respect to the 16 variants identified. In addition to the replication of the phenotypes tested in the discovery GWAS, we observed novel associations related to blood levels of immune cells (eosinophils, neutrophils, monocytes, and lymphocytes) for the asthma-related variants. Conversely, the lung-function variants were associated with phenotypes related to body fat mass. In the ISAAC-assessed cohort, we observed that risk alleles associated with increased fat mass can exacerbate allergic reactions in individuals affected by allergic respiratory diseases. The GTEx-based analysis showed that the variants tested affect the transcriptomic regulation of multiple surrounding genes across several tissues.

Conclusions

This study generated novel data regarding the genetics of respiratory diseases and their comorbidities, providing a deep characterization of loci associated with asthma and lung function.

Allergic Diseases and Atopy Among Schoolchildren in Eastern Croatia

SUMMARY – A cross-sectional study was carried out in Brod-Posavina County, Croatia, to assess the prevalence of allergic diseases and atopy, as well as to investigate the possible etiologic factors for asthma, allergic rhinitis and eczema in childhood. The study included 1687 schoolchildren aged 10-11 years. Data were collected using standardized International Study of Asthma and Allergies in Childhood (ISAAC) Phase II written questionnaire. Skin prick tests were performed to provide an objective measure of atopy, defined as skin reactivity to one or more allergens. Lifetime prevalence of wheezing was 22.7%, rhinitis symptoms 22.5%, and eczema symptoms 17.9%. Period prevalence in the past 12 months was 7.9% for attacks of wheezing, 9.9% for rhinoconjunctivitis symptoms, and 10.1% for eczema symptoms. Of the children in which skin prick test was performed, 20.2% were positive for at least one of the allergens used, with house dust mite sensitization being the most frequent one. Risk factors for allergic disease include allergic disease in family, atopy, sensitization to indoor and outdoor allergens, and environmental tobacco smoke exposure at home. International comparison with the results of other ISAAC Phase II studies showed the Brod-Posavina County to be an area with moderate prevalence of atopy and current asthma symptoms.

Mother's education and offspring asthma risk in 10 European cohort studies

Highly prevalent and typically beginning in childhood, asthma is a burdensome disease, yet the risk factors for this condition are not clarified. To enhance understanding, this study assessed the cohort-specific and pooled risk of maternal education on asthma in children aged 3-8 across 10 European countries. Data on 47,099 children were obtained from prospective birth cohort studies across 10 European countries. We calculated cohort-specific prevalence difference in asthma outcomes using the relative index of inequality (RII) and slope index of inequality (SII). Results from all countries were pooled using random-effects meta-analysis procedures to obtain mean RII and SII scores at the European level. Final models were adjusted for child sex, smoking during pregnancy, parity, mother's age and ethnicity. The higher the score the greater the magnitude of relative (RII, reference 1) and absolute (SII, reference 0) inequity. The pooled RII estimate for asthma risk across all cohorts was 1.46 (95% CI 1.26, 1.71) and the pooled SII estimate was 1.90 (95% CI 0.26, 3.54). Of the countries examined, France, the United Kingdom and the Netherlands had the highest prevalence's of childhood asthma and the largest inequity in asthma risk. Smaller inverse associations were noted for all other countries except Italy, which presented contradictory scores, but with small effect sizes. Tests for heterogeneity yielded significant results for SII scores. Overall, offspring of mothers with a low level of education had an increased relative and absolute risk of asthma compared to offspring of high-educated mothers.

Rhinovirus-induced first wheezing episode predicts atopic but not nonatopic asthma at school age

Background

Persistent childhood asthma is mainly atopy driven. However, limited data exist on the risk factors for childhood asthma phenotypes.

Objective

We sought to identify risk factors at the first severe wheezing episode for current asthma 7 years later and separately for atopic and nonatopic asthma.

Methods

One hundred twenty-seven steroid-naive children with the first severe wheezing episode (90% hospitalized/10% emergency department treated) were followed for 7 years. The primary outcome was current asthma at age 8 years, which was also analyzed separately as atopic and nonatopic asthma. Risk factors, including sensitization, viral cause, and other main asthma risk factors, were analyzed.

Results

At study entry, median age was 11 months (interquartile range, 6-16 months); 17% were sensitized, and 98% were virus positive. Current asthma (n = 37) at 8 years was divided into atopic (n = 19) and nonatopic (n = 18) asthma. The risk factors for current atopic asthma at study entry were sensitization (adjusted odds ratio [OR], 12; P < .001), eczema (adjusted OR, 4.8; P = .014), and wheezing with rhinovirus (adjusted OR, 5.0; P = .035). The risk factors for nonatopic asthma were the first severe respiratory syncytial virus/rhinovirus–negative wheezing episode (adjusted OR, 8.0; P = .001), first wheezing episode at age less than 12 months (adjusted OR, 7.3; P = .007), and parental smoking (adjusted OR, 3.8; P = .028).

Conclusions

The data suggest diverse asthma phenotypes and mechanisms that can be predicted by using simple clinical markers at the time of the first severe wheezing episode. These findings are important for designing early intervention strategies for secondary prevention of asthma.

Association between perfluoroalkyl substance exposure and asthma and allergic disease in children as modified by MMR vaccination

Perfluoroalkyl substances (PFASs) are highly persistent chemicals that might be associated with asthma and allergy, but the associations remain unclear. Therefore, this study examined whether pre- and postnatal PFAS exposure was associated with childhood asthma and allergy. Measles, mumps, and rubella (MMR) vaccination in early life may have a protective effect against asthma and allergy, and MMR vaccination is therefore taken into account when evaluating these associations. In a cohort of Faroese children whose mothers were recruited during pregnancy, serum concentrations of five PFASs - Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) - were measured at three timepoints (maternal serum in pregnancy week 34-36 and child serum at ages 5 and 13 years) and their association with immunoglobulin E (IgE) (cord blood and at age 7 years) and asthma/allergic diseases (questionnaires at ages 5 and 13 years and skin prick test at age 13 years) was determined. A total of 559 children were included in the analyses. Interactions with MMR vaccination were evaluated. Among 22 MMR-unvaccinated children, higher levels of the five PFASs at age 5 years were associated with increased odds of asthma at ages 5 and 13. The associations were reversed among MMR-vaccinated children. Prenatal PFAS exposure was not associated with childhood asthma or allergic diseases regardless of MMR vaccination status. In conclusion, PFAS exposure at age 5 was associated with increased risk of asthma among a small subgroup of MMR-unvaccinated children but not among MMR-vaccinated children. While PFAS exposure may impact immune system functions, this study suggests that MMR vaccination might be a potential effect-modifier.

Allergy-specific Phenome-Wide Association Study for Immunogenes in Turkish Children

To dissect the role of immunogenetics in allergy and asthma, we performed a phenome-wide association study in 974 Turkish children selected from a cross-sectional study conducted using ISAAC (International Study of Asthma and Allergies in Children) Phase II tools. We investigated 9 loci involved in different immune functions (ADAM33, ADRB2, CD14, IL13, IL4, IL4R, MS4A2, SERPINE1, and TNF) with respect to 116 traits assessed through blood tests, hypertonic saline challenge tests, questionnaires, and skin prick tests. Multiple associations were observed for ADAM33: rs2280090 was associated with reduced MEF240% (i.e., the ratio of Mean Expiratory Flow after 240s of hypertonic saline inhalation with respect to the age- and ancestry-matched reference value) and with an increased risk of allergic bronchitis (p = 1.77*10⁻⁴ and p = 7.94*10⁻⁴, respectively); rs3918396 was associated with wheezing and eczema comorbidity (p = 3.41*10⁻⁴). IL4 rs2243250 was associated with increased FEV240 (Forced Expiratory Flow Volume after 240s of hypertonic saline inhalation; p = 4.81*10⁻⁴) and CD14 rs2569190 was associated with asthma diagnosis (p = 1.36*10⁻³). ADAM33 and IL4 appeared to play a role in the processes linked to allergic airway inflammation and lung function. Due to its association with wheezing and eczema comorbidity, ADAM33 may also be involved in the atopic march.

Exposure to mould allergens and rhinoconjunctivitis in Korean children

BACKGROUND

Although rhinitis is the most common allergic disease in children, few studies have explored the causal relationships between mould allergens and rhinitis. Thus, this study aimed to identify factors, especially prior exposure to mould allergens, related to rhinitis and rhinoconjunctivitis in Korean children.

METHODS

Subjects in this study were 12- to 13-year-old children from 40 national middle schools who were participants of the International Study of Asthma and Allergies in Childhood (ISAAC) study in Korea. A total of 3852 children who completed the ISAAC questionnaire in 2010 and underwent a skin prick test (SPT) and blood test were enrolled in this study.

RESULTS

The prevalence of symptoms suggestive of rhinitis or rhinoconjunctivitis in last 12 months was 42.7% and 19.4%, respectively. A parental history of allergies (OR = 2.03, 95% CI = 1.75-2.35; OR = 2.55, 95% CI = 2.13-3.06), visible mould or dampness (OR = 1.28, 95% CI = 1.09-1.51; OR = 1.23, 95% CI = 1.00-1.51), previous exposure to mould allergens (OR = 4.53, 95% CI = 2.32-8.84; OR = 4.98, 95% CI = 2.43-10.20), total IgE levels ≥78 kU/l (OR = 1.44, 95% CI = 1.22-1.69; OR = 1.99, 95% CI = 1.60-2.48) were risk factors for rhinitis and rhinoconjunctivitis.

CONCLUSIONS

This study suggested that previous exposure to mould allergens more influenced rhinitis and rhinoconjunctivitis than visible mould or dampness, and that total IgE levels of ≥78 kU/l, which was the criterion suggested in a study of Asian children, were risk factors for rhinitis diseases.

Asthma and allergy in children with and without prior measles, mumps, and rubella vaccination

BACKGROUND

The existing literature on the association between measles vaccination and subsequent risk of allergic disease is inconclusive. The aim of this study was, therefore, to determine whether measles, mumps, and rubella (MMR) vaccination administered in early childhood was associated with asthma and allergic diseases at ages 5, 7 and 13 yrs in a birth cohort.

METHODS

In the Faroe Islands, 640 children were followed from birth. Follow-up examinations at ages 5, 7 and 13 yrs included a physical examination and a maternal questionnaire about the child's health. At age 7, total and grass-specific IgE was quantified in the child's serum, and at age 13, the children underwent skin prick tests (SPT). The child's vaccination card was reviewed at examinations.

RESULTS

At age 5, 533 of 555 children had been vaccinated for MMR. After confounder adjustment, we found early life MMR vaccination to be associated with a two-third reduction in the odds of asthma (OR: 0.33, 95% CI: 0.12; 0.90) and hypersensitivity/allergy (OR: 0.32, 95% CI: 0.11; 0.88) at age 5, and the substantially decreased odds of asthma were replicated at age 13 (OR: 0.22, 95% CI: 0.08; 0.56). At age 7, serum total IgE was reduced by 62.8% (CI 95%: -84.3%; -11.9%) in the vaccinated children. MMR vaccination was not significantly associated with allergic rhinoconjuctivitis symptoms, eczema, or SPT reactions at age 13.

CONCLUSIONS

MMR vaccination early in life may have a protective effect against allergy at least up to age 7 and against asthma through age 13 yrs.

Risk factors for non-atopic asthma/wheeze in children and adolescents: a systematic review

Background

The study of non-atopic asthma/wheeze in children separately from atopic asthma is relatively recent. Studies have focused on single risk factors and had inconsistent findings.

Objective

To review evidence on factors associated with non-atopic asthma/wheeze in children and adolescents.

Methods

A review of studies of risk factors for non-atopic asthma/wheeze which had a non-asthmatic comparison group, and assessed atopy by skin-prick test or allergen-specific IgE.

Results

Studies of non-atopic asthma/wheeze used a wide diversity of definitions of asthma/wheeze, comparison groups and methods to assess atopy. Among 30 risk factors evaluated in the 43 studies only 3 (family history of asthma/rhinitis/eczema, dampness/mold in the household, and lower respiratory tract infections in childhood) showed consistent associations with non-atopic asthma/wheeze. No or limited period of breastfeeding was less consistently associated with non-atopic asthma/wheeze. The few studies examining the effects of overweight/obesity and psychological/social factors showed consistent associations. We used a novel graphical presentation of different risk factors for non-atopic asthma/wheeze, allowing a more complete perception of the complex pattern of effects.

Conclusions

More research using standardized methodology is needed on the causes of non-atopic asthma.

Breastfeeding and childhood asthma: systematic review and meta-analysis

Asthma and wheezing disorders are common chronic health problems in childhood. Breastfeeding provides health benefits, but it is not known whether or how breastfeeding decreases the risk of developing asthma. We performed a systematic review and meta-analysis of studies published between 1983 and 2012 on breastfeeding and asthma in children from the general population. We searched the PubMed and Embase databases for cohort, cross-sectional, and case-control studies. We grouped the outcomes into asthma ever, recent asthma, or recent wheezing illness (recent asthma or recent wheeze). Using random-effects meta-analyses, we estimated pooled odds ratios of the association of breastfeeding with the risk for each of these outcomes. We performed meta-regression and stratified meta-analyses. We included 117 of 1,464 titles identified by our search. The pooled odds ratios were 0.78 (95% confidence interval: 0.74, 0.84) for 75 studies analyzing "asthma ever," 0.76 (95% confidence interval: 0.67, 0.86) for 46 studies analyzing "recent asthma," and 0.81 (95% confidence interval: 0.76, 0.87) for 94 studies analyzing recent wheezing illness. After stratification by age, the strong protective association found at ages 0-2 years diminished over time. We found no evidence for differences by study design or study quality or between studies in Western and non-Western countries. A positive association of breastfeeding with reduced asthma/wheezing is supported by the combined evidence of existing studies.

Preterm birth and childhood wheezing disorders: a systematic review and meta-analysis

BACKGROUND

Accumulating evidence implicates early life factors in the aetiology of non-communicable diseases, including asthma/wheezing disorders. We undertook a systematic review investigating risks of asthma/wheezing disorders in children born preterm, including the increasing numbers who, as a result of advances in neonatal care, now survive very preterm birth.

METHODS AND FINDINGS

Two reviewers independently searched seven online databases for contemporaneous (1 January 1995-23 September 2013) epidemiological studies investigating the association between preterm birth and asthma/wheezing disorders. Additional studies were identified through reference and citation searches, and contacting international experts. Quality appraisal was undertaken using the Effective Public Health Practice Project instrument. We pooled unadjusted and adjusted effect estimates using random-effects meta-analysis, investigated "dose-response" associations, and undertook subgroup, sensitivity, and meta-regression analyses to assess the robustness of associations. We identified 42 eligible studies from six continents. Twelve were excluded for population overlap, leaving 30 unique studies involving 1,543,639 children. Preterm birth was associated with an increased risk of wheezing disorders in unadjusted (13.7% versus 8.3%; odds ratio [OR] 1.71, 95% CI 1.57-1.87; 26 studies including 1,500,916 children) and adjusted analyses (OR 1.46, 95% CI 1.29-1.65; 17 studies including 874,710 children). The risk was particularly high among children born very preterm (<32 wk gestation; unadjusted: OR 3.00, 95% CI 2.61-3.44; adjusted: OR 2.81, 95% CI 2.55-3.12). Findings were most pronounced for studies with low risk of bias and were consistent across sensitivity analyses. The estimated population-attributable risk of preterm birth for childhood wheezing disorders was ≥3.1%. Key limitations related to the paucity of data from low- and middle-income countries, and risk of residual confounding.

CONCLUSIONS

There is compelling evidence that preterm birth-particularly very preterm birth-increases the risk of asthma. Given the projected global increases in children surviving preterm births, research now needs to focus on understanding underlying mechanisms, and then to translate these insights into the development of preventive interventions.

REVIEW REGISTRATION

PROSPERO CRD42013004965.

Similar prevalence, different spectrum: IgE-mediated food allergy among Turkish adolescents

BACKGROUND

Scarcity of reliable data on food allergy prevalence exists in Turkey. We aimed to assess reported and confirmed IgE-mediated food allergy prevalence, and define the spectrum of allergenic food.

METHODS

We prospectively evaluated the ISAAC Phase II study population for food allergy. Participants that reported experiencing food allergy symptom in the last year and/or were skin prick test positive for a predefined list of food allergens, were interviewed via telephone, and those considered as having food allergy were invited to undergo clinical investigation, including challenge tests.

RESULTS

A total of 6963 questionnaires were available. Parental reported food allergy prevalence and skin prick sensitisation rate were 20.2 ± 0.9% and 5.9 ± 0.6%. According to the above-defined criteria, 1162 children (symptom positive n=909, skin prick test positive n=301, both positive n=48) were selected and 813 (70.0%) were interviewed via telephone. Out of 152 adolescents reporting a current complaint, 87 accepted clinical investigation. There were 12 food allergies diagnosed in nine adolescents, with food allergy prevalence of 0.16 ± 0.11%. The most common foods involved in allergic reactions were walnut (n=3) and beef meat (n=2), followed by hen's egg (n=1), peanut (n=1), spinach (n=1), kiwi (n=1), cheese (n=1), hazelnut (n=1) and peach (n=1).

CONCLUSIONS

While parental reported food allergy prevalence was within the range reported previously, confirmed IgE-mediated food allergy prevalence among adolescents was at least 0.16%, and the spectrum of foods involved in allergy differed from Western countries, implying environmental factors may play a role.

Association of indoor dampness and molds with rhinitis risk: a systematic review and meta-analysis

BACKGROUND

A substantial proportion of the world's population is exposed to indoor dampness-related exposures. Since the 1990s, studies have assessed the relation between indoor dampness and mold and rhinitis, but the evidence has been inconclusive. No previous meta-analysis has been reported on this topic.

OBJECTIVE

We conducted a systematic review and meta-analysis of studies on the relations between indoor dampness and mold and the risk of different types of rhinitis and investigated whether these relations differ according to the type of exposure.

METHODS

A systematic search of the Ovid MEDLINE and EMBASE databases was conducted (1950 through August 2012), and reference lists of relevant articles were reviewed. Cross-sectional, case-control, and cohort studies in children or adults were selected according to a priori criteria and evaluated by 3 authors independently.

RESULTS

Thirty-one studies on rhinitis, allergic rhinitis (AR), or rhinoconjunctivitis were included. In meta-analyses the largest risk was observed in relation to mold odor (rhinitis: 2.18 [95% CI, 1.76-2.71]; AR: 1.87 [95% CI, 0.95-3.68]). The risk related to visible mold was also consistently increased (rhinitis: 1.82 [95% CI, 1.56-2.12]; AR: 1.51 [95% CI, 1.39-1.64]; rhinoconjunctivitis: 1.66 [95% CI, 1.27-2.18]). In addition, exposure to dampness was related to increased risk of all types of rhinitis.

CONCLUSION

This meta-analysis provides new evidence that dampness and molds at home are determinants of rhinitis and its subcategories. The associations were strongest with mold odor, suggesting the importance of microbial causal agents. Our results provide evidence that justifies prevention and remediation of indoor dampness and mold problems, and such actions are likely to reduce rhinitis.

Relationships between molds and asthma suggesting non-allergic mechanisms. A rural-urban comparison

BACKGROUND

A fungal index, based on specific microbial volatile organic compounds (MVOCs) emission, was employed and related to asthma in children from rural and urban dwellings after stratification on the children atopic status.

METHODS

A nested case-control design was used to draw, from 2 cross-sectional surveys, 20 asthmatics and 26 controls living in urban areas, and 24 asthmatics and 25 controls in rural areas. MVOCs levels were assessed in the living-room during one week; during that week, children performed clinical tests and their parents were invited to fill in a questionnaire on respiratory health.

RESULTS

According to the objective fungal index, 70.5% of cases and 49.0% of controls were exposed to molds. More children with current asthma had experienced mold exposure in their homes (OR=3.38, 95% CI (1.16; 9.90)), especially amongst children living in rural areas. Atopic status modified this association: exposure to molds was found to be related to current asthma only in non-atopic children (OR=10.42, 95% CI (2.42; 44.81)). Among urban -dwelling children that could be screened at hospital, asthmatic children living in contaminated dwellings had a higher proportion of blood neutrophils and a lower FEV1 (forced expiratory volume in 1 second) than non-exposed ones.

CONCLUSION

Our findings based on an objective assessment of MVOCs suggest adverse respiratory effects of molds. Our results suggest that when looking at the aetiology of non-atopic asthma, mold exposure should be systematically assessed.

Prenatal and postnatal bisphenol A exposure and asthma development among inner-city children

BACKGROUND

Bisphenol A (BPA) is used widely to manufacture food container linings. Mouse models suggest exposure to BPA might increase allergic inflammation.

OBJECTIVES

We hypothesized that BPA exposure, as assessed based on urinary BPA concentrations, would be associated with increased odds of wheeze and asthma and increased fraction of exhaled nitric oxide (Feno) values in children.

METHODS

The Columbia Center for Children's Environmental Health recruited pregnant women for a prospective birth cohort study (n = 568). Mothers during the third trimester and children at ages 3, 5, and 7 years provided spot urine samples. Total urinary BPA concentrations were measured by using online solid-phase extraction, high-performance liquid chromatography, isotope-dilution tandem mass spectrometry. Wheeze in the last 12 months was measured by using questionnaires at ages 5, 6, and 7 years. Asthma was determined by a physician once between ages 5 and 12 years. Feno values were measured at ages 7 to 11 years.

RESULTS

Prenatal urinary BPA concentrations were associated inversely with wheeze at age 5 years (odds ratio [OR], 0.7; 95% CI, 0.5-0.9; P = .02). Urinary BPA concentrations at age 3 years were associated positively with wheeze at ages 5 years (OR, 1.4; 95% CI, 1.1-1.8; P = .02) and 6 years (OR, 1.4; 95% CI, 1.0-1.9; P = .03). BPA concentrations at age 7 years were associated with wheeze at age 7 years (OR, 1.4; 95% CI, 1.0-1.9; P = .04) and Feno values (β = 0.1; 95% CI, 0.02-0.2; P = .02). BPA concentrations at ages 3, 5, and 7 years were associated with asthma (OR, 1.5 [95% CI, 1.1-2.0], P = .005; OR, 1.4 [95% CI, 1.0-1.9], P = .03; and OR, 1.5 [95% CI, 1.0-2.1], P = .04, respectively).

CONCLUSIONS

This is the first report of an association between postnatal urinary BPA concentrations and asthma in children.

Asthma and atopy in children born by caesarean section: effect modification by family history of allergies - a population based cross-sectional study

Background

Studies on the association of birth by caesarean section (C/S) and allergies have produced conflicting findings. Furthermore, evidence on whether this association may differ in those at risk of atopy is limited. This study aims to investigate the association of mode of delivery with asthma and atopic sensitization and the extent to which any effect is modified by family history of allergies.

Methods

Asthma outcomes were assessed cross-sectionally in 2216 children at age 8 on the basis of parents’ responses to the ISAAC questionnaire whilst skin prick tests to eleven aeroallergens were also performed in a subgroup of 746 children. Adjusted odds ratios of asthma and atopy by mode of delivery were estimated in multivariable logistic models while evidence of effect modification was examined by introducing interaction terms in the models.

Results

After adjusting for potential confounders, children born by C/S appeared significantly more likely than those born vaginally to report ever wheezing (OR 1.36, 95% CI 1.07-1.71), asthma diagnosis (OR 1.41, 95% CI 1.09-1.83) and be atopic (OR 1.67, 95% CI 1.08-2.60). There was modest evidence that family history of allergies may modify the effect of C/S delivery on atopy (p for effect modification=0.06) but this was not the case for the asthma outcomes. Specifically, while more than a two-fold increase in the odds of being a topic was observed in children with a family history of allergies if born by C/S (OR 2.62, 95% CI 1.38-5.00), no association was observed in children without a family history of allergies (OR 1.16, 95% CI 0.64-2.11).

Conclusions

Birth by C/S is associated with asthma and atopic sensitization in childhood. The association of C/S and atopy appears more pronounced in children with family history of allergies.

Prevalence of asthma symptoms and associated factors in schoolchildren from Brazilian Amazon islands

OBJECTIVES

To determine the prevalence of asthma symptoms among schoolchildren living on two different Brazilian Amazon islands and to identify the risk factors related to this condition.

METHODS

A cross-sectional study of 400 schoolchildren (5-8 years old) using written questionnaires produced by the International Study of Asthma and Allergies in Childhood, a skin prick test (allergic sensitization), and a stool examination (for helminthic infection). Nonparametric tests were carried out, and the risk factors were identified by logistic regression.

RESULTS

The prevalence of active asthma symptoms was markedly higher in children living on Outeiro Island (OI) than those living on Combú Island (CBI) (30.5% and 16.5%, respectively). The logistic regression identified several risk factors of asthma symptoms on CBI: parental history of asthma, night coughing in the past year, and "currently have a cat". On OI, the major risk factors were parental history of asthma, personal history of eczema, having two or more older siblings, and night coughing in the past year. The risk factors in common on both the islands were night coughing in the past year and parental history of asthma.

CONCLUSIONS

The prevalence of asthma symptoms was higher in those with a lifestyle closer to that observed in urban areas (i.e., better sanitation and hygiene), reinforcing the protective effect of a rural environment. Different risk factors were associated with asthma symptoms in schoolchildren living on OI and on CBI. This fact may reflect the environmental individuality and particularities of each island.

Sex and atopy influences on the natural history of rhinitis

PURPOSE OF REVIEW

Rhinitis is a common condition associated with significant under-recognized morbidity and impaired quality of life. The natural history of rhinitis is poorly characterized. Better understanding of its natural history and associated risk factors would improve the ability to effectively manage rhinitis in clinical practice. This review focuses on the current research findings on the natural history of rhinitis and how that is influenced by atopy and sex.

RECENT FINDINGS

Recent work from the Isle of Wight Birth Cohort Study has demonstrated that the prevalence of atopic rhinitis increases steadily in the first 18 years of life in both sexes. However, nonatopic rhinitis behaves differently during adolescence. Its prevalence decreases in boys but continues to increase in girls resulting in a female predominance after puberty. Numerous recent studies have proposed potential roles for sex-related and adipose-related hormonal changes in influencing the course of allergic disease. Further research is needed to establish mechanisms that could underlie such findings.

SUMMARY

Rhinitis becomes increasingly common through childhood, with prevalence during adolescence being mediated by differential effects of sex and atopy. Mechanisms to explain these findings await elucidation.

Pediatric allergy and immunology in Turkey

Allergic diseases constitute a significant health problem in Turkey. According to a recent multicenter study, which used the ISAAC questionnaire, the mean prevalence of wheezing, rhinoconjunctivitis, and eczema in 10-yr-old school children during the past year was 15.8%, 23.5%, and 8.1%, respectively. A healthcare level system, regulated by Ministry of Health, is available in Turkey. Pediatric allergists and pediatric immunologists provide patient care at the tertiary level. Currently, 48 centers deliver care for allergic and immunologic diseases in children. There are 136 pediatric and 61 adult allergists/immunologists. Although the number of allergy/clinical immunology specialists is limited, these centers are capable of delivering many of the procedures required for the proper management and diagnosis of allergy/immunology. Pediatric allergy and/or immunology is a subspecialty lasting 3 yr and follows a 4-yr pediatric specialist training. Fellow training involves gaining knowledge in basic and clinical allergy and immunology as well as the performance and interpretation of laboratory procedures in the field of allergy and clinical immunology. The Turkish National Society of Allergy and Clinical Immunology (TNSACI) was officially established in 1989 and currently has 356 members. The society organizes a national congress annually and winter schools for fellowship training as well as training courses for patients and their relatives. TNSACI also has a strong representation in European Academy of Allergy and Clinical Immunology (EAACI) and European Society for Immunodeficiencies (ESID) through its participation in the executive committee, consensus reports, and initiatives in the diagnosis of allergic and immunologic diseases of children. The 30th Congress of the EAACI is also due to be held in Istanbul, Turkey, between June 11 and 15, 2011.

Maternal and childhood asthma: risk factors, interactions, and ramifications

Asthma is emerging as a premier example of a health risk that can largely be molded by the status of the mother and the environmental conditions encountered during sensitive windows of prenatal and early childhood development. While genetic background, allergic status of parents, and predisposition for atopy and inflammation play a role, early-life environmental conditions can completely alter the course of immune and respiratory system development. Environmentally induced alterations that (1) maintain the Th2 bias seen during gestation, (2) block the maturation of innate immune cells and (3) create inflammatory dysfunction in the infant provide the foundation for childhood asthma. No single risk factor can fully explain the increased prevalence of asthma in recent decades but it is assumed that the rapid increase is due to environmental and/or epigenetic changes. Well-established and suspected environmental risk factors cover all categories of early life interactions from diet, exposure to environmental contaminants and drugs, maternal and neonatal infections, hygiene, timing of vaccinations and even the mode of birth delivery. Because asthma is connected to the risk of several comorbid chronic conditions, the benefit of asthma risk reduction and prevention is greater than initially may be apparent. This review discusses strategies to optimize preventative and therapeutic options across life stages.

Is there an association between wheezing and constipation in preschool children? Explanations from a longitudinal birth cohort

OBJECTIVE

To assess whether wheezing and atopic dermatitis were associated with constipation in preschool children and to what extent shared risk factors contribute to this relationship.

METHODS

A population-based sample of 4651 preschool children was used. At the age of 24, 36 and 48 months, a parental report of functional constipation was available according to the Rome II criteria, and data on atopic dermatitis and wheezing were available using age-adapted questionnaires from the International Study of Asthma and Allergies in Childhood. Stepwise multivariate analyses were performed to assess whether body mass index, infection exposure, food allergy and infant nutrition, and parental stress explained the association between wheezing, atopic dermatitis and constipation.

RESULTS

Out of 4651 children, 12-17% had functional constipation between 24 and 48 months. Symptoms of wheezing decreased from 20% to 12% and atopic dermatitis decreased from 30% to 18% at the age of 24 and 48 months respectively. Between the age of 24 and 48 months, wheezing symptoms were significantly associated with functional constipation (OR 1.17; 1.02 to 1.34) but these results were mainly explained by the child's exposure to infections and use of antibiotics (adjusted odds ratio 1.08; 95% CI 0.95 to 1.24). No significant association was found between symptoms of atopic dermatitis and functional constipation (OR 1.08; 95% CI 0.94 to 1.23).

CONCLUSIONS

These findings suggest that functional constipation coexists with wheezing in childhood but is mainly explained by the child's infection exposure and use of antibiotics. Therefore, an independent association between respiratory symptoms and functional bowel disorders as suggested in previous studies is questionable.