Meta-analysis of prevalence of wheezing and recurrent wheezing in infants

Daycare use of disinfectants and cleaning products and wheeze among children: Cross-sectional analyses in the French CRESPI cohort

BACKGROUND

Evidence is mounting that domestic use of disinfectants and cleaning products (DCP), particularly in spray form, is associated with wheezing in children. Beyond the home environment, many children are also exposed to DCP in daycare. The links between daycare exposures to DCP and child respiratory health have never before been studied.

OBJECTIVES

Evaluate the associations between daycare DCP use and wheeze among children.

METHODS

This cross-sectional study draws upon the data at inclusion for 536 children (mean age: 22.3 months; 47.4 % female) of the French CRESPI cohort (108 daycares in the Paris region, 2019-2022). Exposure to DCP was evaluated using a barcode-scanning smartphone application with an embedded questionnaire. An exposure score was calculated as the sum of frequencies of use of DCP for each daycare. Child wheezing outcomes (ever wheeze since birth, recurrent wheeze (≥3 times since birth), and wheeze ever treated with inhaled corticosteroids (ICS)) were evaluated by parental questionnaire. Associations between daycare DCP exposure and wheezing outcomes were analyzed with Generalized Estimating Equations to account for a possible center effect, and adjusted for child age, parental smoking status, parental educational attainment, and daycare size.

RESULTS

The prevalence of ever wheeze was 32.1 %, that of recurrent wheeze 13.3 %, and that of wheeze ever treated with ICS 14.5 %. Above-median exposure scores (vs. ≤ median exposure scores) were associated with higher odds of wheeze ever treated with ICS (Odds Ratio = 1.72, 95 % Confidence Interval: 1.07-2.75) and ever wheeze (1.40, 0.98-2.00), but not with recurrent wheeze (1.35, 0.79-2.31). Relationships between specific DCP application modes and wheezing outcomes did not suggest a predominant role of specific modes.

DISCUSSION

Given the observed association between daycare DCP use and wheeze in children, measures which limit child exposure to DCP in care settings should be considered.

Residential greenness and pollen exposure across gestational trimesters in relation to preschool wheezing: Results for the PIPO birth cohort

INTRODUCTION

Previous studies on prenatal green space exposure and early respiratory health show inconsistent results. This may reflect stage-specific in utero effects and pollen influence. We examine associations of surrounding greenness and pollen exposure during pregnancy (overall and by trimester) with preschool wheezing, and assess potential mediation by pollen.

METHODS

We used data from the PIPO birth cohort (n = 860). Wheezing was reported biannually between 18 and 48 months of age. Residential greenness was measured with Normalized Difference Vegetation Index (NDVI) in 100 and 250 m buffer. Cumulative grass and birch pollen was estimated using modelled airborne pollen counts and categorized per trimester into no, low and high. All exposures were assessed for the overall pregnancy and per trimester. We used Generalized Estimated Equations to obtain odds ratios (OR) and 95% confidence intervals (CI). To assess mediation by pollen we used a data duplication algorithm with a generalized estimation approach.

RESULTS

Approximately 10% of participants wheezed. During pregnancy, greenness (OR = 1.07, CI: 1.05-1.08) and grass pollen exposure (OR = 1.09, CI: 1.03-1.15) increased the odds of wheezing, while birch pollen decreased it (OR = 0.86, CI:0.87-1.00). Per trimester, more greenness during the 2nd trimester increased the odds (OR = 1.21, CI: 1.16-1.26), whereas third-trimester greenness decreased it (OR = 0.87, CI: 0.84-0.91). Grass pollen exposure in the 1st and 3rd trimesters increased the odds of wheezing (OR = 1.23, CI: 1.12-1.34 and OR = 1.13, CI: 1.00-1.27, respectively), while birch pollen exposure in the 1st and 2nd trimesters decreased the odds (OR = 0.88, CI: 0.77-1.00 and OR = 0.83, CI: 0.73-0.95, respectively). No significant associations were found for greenness in the 1st trimester, grass pollen in the 2nd trimester, and birch pollen in the 1st and 3rd trimester. Mediation analysis showed large uncertainty.

DISCUSSION

Surrounding greenness and pollen exposure during pregnancy may impact the likelihood of preschool wheezing differently depending on the timing of exposure and the pollen type.

Disparities in prevalence and outcomes of respiratory disease in low- and middle-income countries

OBJECTIVES

To provide a comprehensive overview of disparities in prevalence and outcomes of respiratory diseases and notable challenges for providing optimal treatment to pediatric patients with respiratory diseases living in low- and middle-income countries (LMICs), as an input to help better understand the roots of respiratory health disparities.

METHODS

We conducted a narrative review of relevant literature published in electronic databases from inception to February 2023 that present data on disparities in prevalence and outcomes of respiratory disease in LMICs. Additionally, we included studies that describe and discuss challenges for providing optimal treatment to pediatric patients with respiratory diseases living in LMICs.

RESULTS

A number of early life exposures have been associated with adverse respiratory outcomes in later life. Several studies have shown marked geographical variations in the prevalence and burden of pediatric asthma, with consistently lower prevalence rates but significantly higher burdens and worse outcomes in LMICs. There is a wide range of challenges that adversely affect the efficient care of children with respiratory diseases that can be classified into three categories: patient-related factors, social/environmental factors, and factors related to healthcare providers or the healthcare system.

CONCLUSIONS

Respiratory health disparities in children living in LMICs represent a global public health issue mainly explained by an unequal distribution of preventable and modifiable risk factors for respiratory diseases across different demographic groups.

The Prevalence of Childhood Asthma, Respiratory Symptoms and Associated Air Pollution Sources Among Adolescent Learners in Selected Schools in Vhembe District, South Africa

This study investigated the prevalence of childhood asthma and respiratory symptoms with their associated air pollution sources among adolescents aged 13-14 years residing in a Malaria-endemic region.

METHODS

A cross-sectional survey was conducted with 2855 adolescents from fourteen (14) selected schools in communities exposed to high levels of air pollution from indoor residual spraying (IRS) that is used for malaria vector control in the Vhembe region. Data were collected using a self-administered standardized International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Statistical software STATA version 17 was used to analyze the data. Binary logistic regression was used to determine the relationship between air pollution sources and childhood asthma/symptoms.

RESULTS

The prevalences of asthma, 'wheeze ever' and 'wheeze in the past' were 18.91%, 37.69% and 24.69%, respectively. The results from the adjusted binary logistic regression model indicated that exposure to tobacco smoke (OR = 1.84; 95% CI: 1.08-3.16), smoking a water pipe (OR = 1.65; 95% CI: 1.16-2.36) and the use of paraffin as fuel for heating (OR = 1.70; 95% CI: 0.97-2.88) and cooking (OR = 0.48; 95% CI: 0.29-1.00) were significant risk factors for asthma. Trucks passing through the streets, having a cat at home and using open fires were significantly associated with 'wheeze in the past'. Finally, using gas for cooking (OR = 0.72; 95% CI: 0.53-0.99), open fires for heating (OR = 0.53; 95% CI: 0.35-0.80) and smoking a water pipe (OR = 2.47; 95% CI: 1.78-3.44) were associated with 'wheeze ever'.

CONCLUSIONS

School children living in these communities had an increased risk of developing asthma and presenting with wheezing due to exposure to environmental air pollution sources.

Longitudinal transcriptional immune profiles and persistent wheezing in moderate-to-late preterm infants

BACKGROUND

Prematurity is associated with an increased risk of persistent wheezing but the underlying mechanisms are not well defined. The aim of this study was to identify blood transcriptional profiles associated with the development of wheezing in a cohort of moderate to late preterm infants and to define immune gene expression changes associated with wheezing.

MATERIALS AND METHODS

A convenience sample of a multicenter birth cohort (SAREPREM) of moderate-late preterm children followed during the first 3 years of life was analyzed. Children were enrolled in the first 2 weeks of life (Y0) and longitudinally evaluated at 1 (Y1), 2 (Y2), and 3 years (Y3) of age, for the presence of wheezing and to obtain samples for transcriptional profile analysis. Samples were processed on Illumina HT12 chips and genomic expression analyses performed with R programming, modular analysis for biological function, and QuSAGE for quantitative gene expression.

RESULTS

Seventy-six children were included in the study; 33 were classified as non-wheezing and 43 (56.6%) in the wheezing group. At Y0, children who developed wheezing had decreased expression of interferon genes and increased expression of B cell genes compared with the non-wheezing group. These changes in IFN and B cell gene expression were especially significant in children with late/persistent wheezing compared with transient wheezers.

CONCLUSIONS

Changes in IFN and B lymphocyte gene expression identified in early life suggest the existence of specific immunological mechanisms that play an important role in the development of wheezing in late-preterm infants.

Environmental exposures associated with early childhood recurrent wheezing in the mother and child in the environment birth cohort: a time-to-event study

BACKGROUND

Antenatal factors and environmental exposures contribute to recurrent wheezing in early childhood.

AIM

To identify antenatal and environmental factors associated with recurrent wheezing in children from birth to 48 months in the mother and child in the environment cohort, using time-to-event analysis.

METHOD

Maternal interviews were administered during pregnancy and postnatally and children were followed up from birth to 48 months (May 2013-October 2019). Hybrid land-use regression and dispersion modelling described residential antenatal exposure to nitrogen dioxide (NO2) and particulate matter of 2.5 µm diameter (PM2.5). Wheezing status was assessed by a clinician. The Kaplan-Meier hazard function and Cox-proportional hazard models provided estimates of risk, adjusting for exposure to environmental tobacco smoke (ETS), maternal smoking, biomass fuel use and indoor environmental factors.

RESULTS

Among 520 mother-child pairs, 85 (16%) children, had a single wheeze episode and 57 (11%) had recurrent wheeze. Time to recurrent wheeze (42.9 months) and single wheeze (37.8 months) among children exposed to biomass cooking fuels was significantly shorter compared with children with mothers using electricity (45.9 and 38.9 months, respectively (p=0.03)). Children with mothers exposed to antenatal ETS were 3.8 times more likely to have had recurrent wheeze compared with those not exposed (adjusted HR 3.8, 95% CI 1.3 to 10.7). Mean birth month NO2 was significantly higher among the recurrent wheeze category compared with those without wheeze. NO2 and PM2.5 were associated with a 2%-4% adjusted increased wheezing risk.

CONCLUSION

Control of exposure to ETS and biomass fuels in the antenatal period is likely to delay the onset of recurrent wheeze in children from birth to 48 months.

The wheezy infant: A viewpoint from low-middle income countries

OBJECTIVE

To review the recent evidence in the literature of various aspects of recurrent/severe wheezing in children under 3 in low-middle income countries [LMICS].

SOURCES

A non-systematic review including articles in English. We mainly selected publications from the last 5 years. Studies on epidemiology, aetiology, diagnosis, treatment, and prevention were included in the search. We reviewed differential diagnoses of wheezing that focused on LMICS. We also reviewed aspects of prevention.

SUMMARY OF THE FINDINGS

Many epidemiological studies have shown a variable but significant number of wheezy infants [WI] cases in LMICS when compared to other countries. The differential diagnosis of causes of wheezing in this age group is mandatory, taking into account local facilities. Few treatment options have been well studied for this age group. In LMICS, a pragmatic approach could be considered, as described in the article. It is difficult to study primary prevention for WI and secondary prevention (mainly environmental) may have some impact. A schematic approach for recurrent wheezers is presented, which takes into account settings with limited resources.

CONCLUSION

Severely or recurrently wheezy children under 3 is a common clinical issue in LMICS. Studies on this age group are needed to reduce the significant morbidity. It may be possible to lower the high burden of wheezing in this age group by selecting the phenotype which may respond to inhaled steroids.

Airway epithelium respiratory illnesses and allergy (AERIAL) birth cohort: study protocol

Introduction

Recurrent wheezing disorders including asthma are complex and heterogeneous diseases that affect up to 30% of all children, contributing to a major burden on children, their families, and global healthcare systems. It is now recognized that a dysfunctional airway epithelium plays a central role in the pathogenesis of recurrent wheeze, although the underlying mechanisms are still not fully understood. This prospective birth cohort aims to bridge this knowledge gap by investigating the influence of intrinsic epithelial dysfunction on the risk for developing respiratory disorders and the modulation of this risk by maternal morbidities, in utero exposures, and respiratory exposures in the first year of life.

Methods

The Airway Epithelium Respiratory Illnesses and Allergy (AERIAL) study is nested within the ORIGINS Project and will monitor 400 infants from birth to 5 years. The primary outcome of the AERIAL study will be the identification of epithelial endotypes and exposure variables that influence the development of recurrent wheezing, asthma, and allergic sensitisation. Nasal respiratory epithelium at birth to 6 weeks, 1, 3, and 5 years will be analysed by bulk RNA-seq and DNA methylation sequencing. Maternal morbidities and in utero exposures will be identified on maternal history and their effects measured through transcriptomic and epigenetic analyses of the amnion and newborn epithelium. Exposures within the first year of life will be identified based on infant medical history as well as on background and symptomatic nasal sampling for viral PCR and microbiome analysis. Daily temperatures and symptoms recorded in a study-specific Smartphone App will be used to identify symptomatic respiratory illnesses.

Discussion

The AERIAL study will provide a comprehensive longitudinal assessment of factors influencing the association between epithelial dysfunction and respiratory morbidity in early life, and hopefully identify novel targets for diagnosis and early intervention.

Vitamin D Level and Immune Modulation in Children with Recurrent Wheezing

INTRODUCTION AND AIM

A direct causal relationship between vitamin D (vit D) deficiency and recurrent wheezing has not been proven. The present study investigated the role of vit D in enhancing the risk of asthma or recurrent wheezing by modifying the intensity of the inflammatory process.

MATERIAL AND METHOD

Forty children with wheezing presenting at the emergency service and sixteen healthy control subjects were included in the study. Children with wheezing were either in the first episode (20) or with recurrent wheezing (20). Children with chronic diseases, and other conditions that present with acute wheezing or that might influence the vit D level, were excluded. Blood samples were taken at presentation and 3-6 months later, to evaluate the serum levels of total IgE, vit D, IL-10 and IL-31. Statistical analysis was performed using the SPSS 25 program, with a significance level of p < 0.05.

RESULTS AND CONCLUSION

The vit D level was lower in patients with recurrent wheezing compared with those with a single episode and with the control group, and this increased with time. IL-10 was significantly higher in children with wheezing than in the control group, with the highest values in those with an acute episode of wheezing. IL-31 was higher in children with recurrent wheezing than in those with a first episode only at the initial point, while at the final time point it was lower. Low levels of vit D appear to be detected more frequently in recurrent wheezing than in simple wheezing. Immune modulation, as measured by Th2 status reflected by IL-10 and IL-31 levels, appears to depend on the wheezing phenotype and on the general health status.

Effects and safety of hypertonic saline combined with airway clearance in non-hospitalized children with recurrent wheezing

Background

The International Study of Wheezing in Infants defines recurrent wheezing as the presence of three or more medically documented episodes of wheezing within one year. To date, there is no evidence on the use of hypertonic saline (HS) combined with airway clearance techniques (ACT) for children with recurrent wheezing treated in an outpatient setting. Therefore, this is the first study to explore the use of such interventions in infants with recurrent wheezing.

Objectives

To evaluate the effects and safety of a three-month protocol including HS and ACT for non-hospitalized infants with recurrent wheezing.

Methods

Randomized, double-blind, controlled trial, including outpatient infants with recurrent wheezing. Children were randomized to either 3% HS or 0.9% saline groups and were treated with bronchodilator and nebulized with the respective solutions before ACT. The primary outcome was the Wang score. Secondary outcomes included the number of hospitalizations and respiratory crisis, need for rescue medication, and school absences. All variables were measured during the three previous months from inclusion and during intervention period. The study protocol was registered at ClinicalTrials.gov (NCT04331496) on March, 31, 2020.

Results

Forty children were included. Regarding immediate effects, significant differences (p < 0 . 001 ) were found for time, but not for group or interaction (group × time), in all outcome variables (increase in SpO2, decrease in heart and respiratory rate, wheezing episodes, retraction, and Wang score). Comparing the previous three months with the study period, there were significant differences in both groups for the severity of crisis (p < 0 . 001 ) and medication steps (p = 0 . 002 ).

Conclusion

A three-month protocol including HS and ACT for outpatient infants with recurrent wheezing was safe and reduced morbidity. No differences were found between the use of HS and 0.9% saline.

Effects of prenatal alcohol exposure on infant lung function, wheeze, and respiratory infections in Australian children

BACKGROUND

Prenatal alcohol exposure (PAE) is a known risk factor for a range of adverse outcomes, such as facial dysmorphism, adverse birth outcomes, and neurodevelopmental changes. Preclinical research shows that PAE also inhibits lung development, lowers surfactant protein expression, has detrimental effects on alveolar macrophages, and decreases both T and B cell numbers. However, clinical evidence of respiratory impacts from PAE is limited. This study explored whether lung function, wheeze, and incidence of respiratory infections differ in children with PAE compared with unexposed children.

METHODS

Data from the Barwon Infant Study (n = 1074) were examined. PAE data were extracted from maternal questionnaires at trimesters 1 and 2 (combined), and trimester 3, and included as "total standard drinks" during each trimester and total pregnancy intake, a binary yes/no for PAE, and binge drinking (>5 standard drinks in one session). Respiratory outcomes were parent-reported wheeze, lung function (measured by multiple breath washout), and parent report and medical record indicators of health service attendances for respiratory conditions. Linear and logistic regressions were performed to quantify relationships between PAE and respiratory outcomes, controlling for socioeconomic status, birthweight, sex, gestational age, and maternal smoking.

RESULTS

Binge drinking was associated with increased health service attendance for respiratory condition(s) in the first 12 months of life (OR = 5.0, 95% CI (1.7, 20.7), p = 0.008). We did not find a relationship between binary PAE and binge drinking with lung function at 4 weeks of age or wheeze at 12 months. The number of standard drinks consumed in trimester two was associated with a lower lung clearance index (β = -0.011 turnovers, 95% CI (-0.0200, -0.0013), p = 0.03), and a small increase in functional residual capacity (β = 0.34 mL, 95% CI (0.02, 0.66), p = 0.04).

CONCLUSIONS

We found an association between binge drinking and health service utilization for respiratory conditions in infancy, but no evidence that low-level PAE was associated with adverse respiratory outcomes.

Association between household cleaning product exposure in infancy and development of recurrent wheeze and asthma

OBJECTIVE

Household chemicals may act as irritants in the lungs; however, their association with recurrent wheeze and asthma in children remains controversial. We aimed to investigate if household cleaning product exposure in infancy is associated with recurrent wheezing and asthma development in children.

METHODS

We analyzed data from two cohorts: MARC-35 consisting of 815 children with history of severe bronchiolitis in infancy, and MARC-43 consisting of 525 healthy children in infancy. Frequency of use of cleaning product at the child's home during infancy was collected via telephone interview with parents. Outcomes were recurrent wheezing by age 3 years and asthma diagnosis at age 6 years.

RESULTS

In MARC-35, there was no association between cleaning product exposure in infancy and recurrent wheeze (adjusted HR = 1.01 [95% CI 0.66-1.54] for 4-7 days/week exposure frequency), nor asthma (adjusted OR = 0.91 [95% CI 0.51-1.63]). In MARC-43, there was also no association between cleaning product exposure in infancy and recurrent wheeze (adjusted HR = 0.69 [95% CI 0.29-1.67] for 4-7 days/week exposure frequency).

CONCLUSION

We found no association between household cleaning product exposure in infancy and later development of recurrent wheeze or asthma, even among children who are at high risk for asthma due to history of severe bronchiolitis.

Antiasthmatic prescriptions in children with and without congenital anomalies: a population-based study

OBJECTIVES

To explore the risk of being prescribed/dispensed medications for respiratory symptoms and breathing difficulties in children with and without congenital anomalies.

DESIGN

A EUROlinkCAT population-based data linkage cohort study. Data on children with and without congenital anomalies were linked to prescription databases to identify children who did/did not receive antiasthmatic prescriptions. Data were analysed by age, European region, class of antiasthmatic, anomaly, sex, gestational age and birth cohort.

SETTING

Children born 2000-2014 in six regions within five European countries.

PARTICIPANTS

60 662 children with congenital anomalies and 1 722 912 reference children up to age 10 years.

PRIMARY OUTCOME MEASURE

Relative risks (RR) of >1 antiasthmatic prescription in a year, identified using Anatomical Therapeutic Chemical classification codes beginning with R03.

RESULTS

There were significant differences in the prescribing of antiasthmatics in the six regions. Children with congenital anomalies had a significantly higher risk of being prescribed antiasthmatics (RR 1.41, 95% CI 1.35 to 1.48) compared with reference children. The increased risk was consistent across all regions and all age groups. Children with congenital anomalies were more likely to be prescribed beta-2 agonists (RR 1.71, 95% CI 1.60 to 1.83) and inhaled corticosteroids (RR 1.74, 95% CI 1.61 to 1.87). Children with oesophageal atresia, genetic syndromes and chromosomal anomalies had over twice the risk of being prescribed antiasthmatics compared with reference children. Children with congenital anomalies born <32 weeks gestational age were over twice as likely to be prescribed antiasthmatics than those born at term (RR 2.20, 95% CI 2.10 to 2.30).

CONCLUSION

This study documents the additional burden of respiratory symptoms and breathing difficulties for children with congenital anomalies, particularly those born preterm, compared with children without congenital anomalies in the first 10 years of life. These findings are beneficial to clinicians and healthcare providers as they identify children with greater morbidity associated with respiratory symptoms, as indicated by antiasthmatic prescriptions.

Clinical predictors of wheeze trajectories and associations with allergy in Asian children

BACKGROUND

Childhood wheezing is a highly heterogeneous condition with an incomplete understanding of the characteristics of wheeze trajectories, particularly for persistent wheeze.

OBJECTIVE

To characterize predictors and allergic comorbidities of distinct wheeze trajectories in a multiethnic Asian cohort.

METHODS

A total of 974 mother-child pairs from the prospective Growing Up in Singapore Towards healthy Outcomes (GUSTO) cohort were included in this study. Wheeze and allergic comorbidities in the first 8 years of life were assessed using the modified International Study of Asthma and Allergies in Childhood questionnaires and skin prick tests. Group-based trajectory modeling was used to derive wheeze trajectories and regression was used to assess associations with predictive risk factors and allergic comorbidities.

RESULTS

There were 4 wheeze trajectories derived, including the following: (1) early-onset with rapid remission from age 3 years (4.5%); (2) late-onset peaking at age 3 years and rapidly remitting from 4 years (8.1%); (3) persistent with a steady increase to age 5 years and high wheeze occurrence until 8 years (4.0%); and (4) no or low wheeze (83.4%). Early-onset wheezing was associated with respiratory infections during infancy and linked to subsequent nonallergic rhinitis throughout childhood. Late-onset and persistent wheeze shared similar origins characterized by parent-reported viral infections in later childhood. However, persistent wheezing was generally more strongly associated with a family history of allergy, parent-reported viral infections in later childhood, and allergic comorbidities as compared with late-onset wheezing.

CONCLUSION

The timing of viral infection occurrence may determine the type of wheeze trajectory development in children. Children with a family history of allergy and viral infections in early life may be predisposed to persistent wheeze development and the associated comorbidities of early allergic sensitization and eczema.

Airway Epithelium Respiratory Illnesses and Allergy (AERIAL) birth cohort: study protocol

Introduction

Recurrent wheezing disorders including asthma are complex and heterogeneous diseases that affect up to 30% of all children, contributing to a major burden on children, their families, and global healthcare systems. It is now recognized that a dysfunctional airway epithelium plays a central role in the pathogenesis of recurrent wheeze, although the underlying mechanisms are still not fully understood. This prospective birth cohort aims to bridge this knowledge gap by investigating the influence of intrinsic epithelial dysfunction on the risk for developing respiratory disorders and the modulation of this risk by maternal morbidities, in utero exposures, and respiratory exposures in the first year of life.

Methods and Analysis

The Airway Epithelium Respiratory Illnesses and Allergy (AERIAL) study is nested within the ORIGINS Project and will monitor 400 infants from birth to five years. The primary outcome of the AERIAL study will be the identification of epithelial endotypes and exposure variables that influence the development of recurrent wheezing, asthma, and allergic sensitisation. Nasal respiratory epithelium at birth to six weeks, one, three, and five years will be analysed by bulk RNA-seq and DNA methylation sequencing. Maternal morbidities and in utero exposures will be identified on maternal history and their effects measured through transcriptomic and epigenetic analyses of the amnion and newborn epithelium. Exposures within the first year of life will be identified based on infant medical history as well as on background and symptomatic nasal sampling for viral PCR and microbiome analysis. Daily temperatures and symptoms recorded in a study-specific Smartphone App will be used to identify symptomatic respiratory illnesses.

Ethics and Dissemination

Ethical approval has been obtained from Ramsey Health Care HREC WA-SA (#1908). Results will be disseminated through open-access peer-reviewed manuscripts, conference presentations, and through different media channels to consumers, ORIGINS families, and the wider community.

Azithromycin attenuates wheezing after pulmonary inflammation through inhibiting histone H3K27me3 hypermethylation mediated by EZH2

BACKGROUND

Histone methylation modification plays an irreplaceable role in the wheezing diseases. The aim of this study was to explore whether azithromycin (AZM) attenuates post-inflammatory wheezing through inhibiting hypermethylation of histone H3K27me3 mediated by EZH2.

RESULTS

A randomized controlled trial was conducted on 227 children who underwent fiber-optic bronchoscopy, and bronchoalveolar lavage fluid (BALF) was collected for analyses. The expressions of IL-6, IL-2, NF-κB P65, EZH2 and H3K27me3 in the BALF of wheezing cases were significantly increased when compared with levels in non-wheezing cases (P < 0.05), while IL-10 was decreased (P < 0.05). AZM attenuated the overexpression of NF-κB P65, EZH2 and H3K27me3 in wheezing cases (P < 0.05) and shortened the time of wheezing in wheezing cases (P < 0.05). An in vitro model of inflammation was established using rat alveolar macrophages induced by lipopolysaccharide (LPS). AZM, SN50 (a NK-κB inhibitor) and GSK126 (an EZH2 inhibitor) attenuated the overexpression of EZH2, NF-κB P65 and H3K27me3 induced by LPS in rat alveolar macrophages (P < 0.05). AZM, SN50 and GSK126 normalized the decreased expression of IL-10 induced by LPS in the same samples (P < 0.05). Co-immunoprecipitation results showed that H3K27me3 interacted with EZH2 and NF-κB P65, and immunofluorescence data showed that AZM and SN50 inhibited LPS-induced NF-κB P65 nuclear translocation in rat alveolar macrophages.

CONCLUSION

Histone H3K27me3 hypermethylation mediated by EZH2 may be involved in wheezing after pulmonary inflammation. AZM attenuated wheezing after pulmonary inflammation by inhibiting NF-κB P65-related hypermethylation of H3K27me3 mediated by EZH2.

Applied causal inference methods for sequential mediators

BACKGROUND

Mediation analysis aims at estimating to what extent the effect of an exposure on an outcome is explained by a set of mediators on the causal pathway between the exposure and the outcome. The total effect of the exposure on the outcome can be decomposed into an indirect effect, i.e. the effect explained by the mediators jointly, and a direct effect, i.e. the effect unexplained by the mediators. However finer decompositions are possible in presence of independent or sequential mediators.

METHODS

We review four statistical methods to analyse multiple sequential mediators, the inverse odds ratio weighting approach, the inverse probability weighting approach, the imputation approach and the extended imputation approach. These approaches are compared and implemented using a case-study with the aim to investigate the mediating role of adverse reproductive outcomes and infant respiratory infections in the effect of maternal pregnancy mental health on infant wheezing in the Ninfea birth cohort.

RESULTS

Using the inverse odds ratio weighting approach, the direct effect of maternal depression or anxiety in pregnancy is equal to a 59% (95% CI: 27%,94%) increased prevalence of infant wheezing and the mediated effect through adverse reproductive outcomes is equal to a 3% (95% CI: -6%,12%) increased prevalence of infant wheezing. When including infant lower respiratory infections in the mediation pathway, the direct effect decreases to 57% (95% CI: 25%,92%) and the indirect effect increases to 5% (95% CI: -5%,15%). The estimates of the effects obtained using the weighting and the imputation approaches are similar. The extended imputation approach suggests that the small joint indirect effect through adverse reproductive outcomes and lower respiratory infections is due entirely to the contribution of infant lower respiratory infections, and not to an increased prevalence of adverse reproductive outcomes.

CONCLUSIONS

The four methods revealed similar results of small mediating role of adverse reproductive outcomes and early respiratory tract infections in the effect of maternal pregnancy mental health on infant wheezing. The choice of the method depends on what is the effect of main interest, the type of the variables involved in the analysis (binary, categorical, count or continuous) and the confidence in specifying the models for the exposure, the mediators and the outcome.

Efficacy of three different budesonide treatments in Chinese preschool children with recurrent wheezing

To explore and compare the clinical control of three atomized inhalation budesonide (BUD) regimens for Chinese preschool children with recurrent wheezing using Test for Respiratory and Asthma Control (TRACK) scores. A total of 474 preschool children with positive Modified Asthma Predictive Index (mAPI) were randomly assigned to a daily group (initially given inhaled BUD 1 mg once a day and assessed every 4 weeks; if symptom were well controlled for 12 weeks, the dose was reduced to 25-50% of the previous dose until afinal dose of 0.25 mg once a day, maintained until 52 weeks), an intermittent high-dose group (1 mg twice daily for 7 days starting early during a predefined respiratory tract illness) and an intermittent medium-dose group (0.5 mg twice daily as soon as they contacted allergens or experienced nasal congestion, a runny nose, cough or other suspicious respiratory symptoms and continuing until symptoms were reduced or risk factors were absent for 3 days) for 52 weeks of treatment. The TRACK questionnaire was administered every 4 weeks. When TRACK scores were ≥ 80, symptoms were considered to be controlled. The average TRACK scores of the three groups after treatment were significantly higher than those before treatment (P < 0.001). There were no significant differences in the average TRACK scores and control rate after treatment at every 4 weeks in the three groups (P > 0.05). Te number of systemic glucocorticoid courses, urgent care visits for wheezing, and wheezing episodes before and after treatment were significantly different within each of the three groups (P < 0.001), but not among the three groups (P > 0.05). In clinical treatment of children, one of the three treatment options can be selected according to the specific situation case of mAPI- positive recurrent wheezing children.

The impact of the COVID-19 pandemic on respiratory morbidity during infancy: A birth-cohort study

OBJECTIVE

To evaluate the incidence of wheezing and overall respiratory morbidity in healthy infants born during the first peak of the coronavirus disease-2019 (COVID-19) pandemic, compared with infants born during the preceding year.

METHODS

This was a single-center retrospective birth cohort study to compare a cohort of children born between February and March 2020 (COVID-19 group) to a control group of children born between February and March 2019 (pre-COVID-19 group). At 1 year of age, we collected respiratory data using parental and telephone questionnaires.

PRIMARY OUTCOME

wheezing incidence and/or bronchodilator use.

SECONDARY OUTCOMES

recurrent wheezing, emergency-room visits, hospital admissions, pneumonia diagnosis, and admissions due to lower-respiratory-tract-infections (LRTI). We included the following covariate risk factors in the logistic regression models; atopy, daycare attendance, breastmilk feeding, parental smoking, C-section, siblings, and gestational age.

RESULTS

We enrolled 588 infants, 294 in each group (48% males). Demographic, perinatal, and atopic characteristics were similar between the groups. Compared to the pre-COVID-19 group, infants born during the COVID-19 period were significantly less likely to report wheezing and/or bronchodilator use (adjusted-odds ratio [OR], 0.4; 95% confidence interval [CI] 0.28-0.59), systemic steroid use, (adjusted-OR, 0.47; 95% CI 0.24-0.91), emergency-room visits (adjusted-OR, 0.36; 95% CI 0.17-0.72), LRTI admissions (adjusted-OR, 0.2; 95% CI 0.05-0.74), or pneumonia diagnosis (adjusted-OR, 0.22; 95% CI 0.09-0.53).

CONCLUSIONS

This study investigated wheezing and respiratory morbidity over the first year of the COVID-19 pandemic in infants born during the first peak of COVID-19. The study demonstrated a significant decrease in most aspects of respiratory morbidity. A longitudinal follow-up study to explore the subsequent impact of these findings is warranted.

The Associations of Caesarean Delivery With Risk of Wheezing Diseases and Changes of T Cells in Children

Objectives

This study aimed to assess the associations of caesarean delivery (CD) with risk of wheezing diseases and changes of immune cells in children.

Design

The cross-sectional study was conducted between May, 2020 and April, 2021.

Setting and participants

The study was conducted in Shanghai Children’s Medical Center, Shanghai, China. A total of 2079 children with a mean age of 36.97 ± 40.27 months and their guardians were included in the present study via face-to-face inquiry and physical examination by clinicians.

Methods

Logistic regression was applied to estimate odds ratio (ORs) and 95% confidence intervals (CIs) for the association between CD and first episode of wheezing (FEW) or asthma. Models were adjusted for premature or full-term delivery, exclusive breastfeeding (at least 4 months) or not.

Results

Among the 2079 children, 987 children (47.47%) were born by CD and 1092 (52.53%) by vaginal delivery (VD). Children delivered by caesarean had significantly lower gestational age (P<0.01) compared with those who delivered vaginally. Our results also showed that CD was related to increased risk of FEW by the age of 3(adjusted OR 1.50, 95%CI 1.06, 2.12) and increased tendency to develop asthma by the age of 4 (adjusted OR 3.16, 95%CI 1.25, 9.01). The subgroup analysis revealed that the negative effects of CD on asthma were more obvious in children without exclusive breastfeeding (adjusted OR 4.93, 95%CI 1.53, 21.96) or without postnatal smoking exposure (adjusted OR 3.58, 95%CI 1.20, 13.13). Furthermore, compared with children born through VD, a significant change of the T cells (increased proportion of CD4+ T cells and decreased number and proportion of CD8+ T cells) were observed before the age of one in the CD group. However, the changes were insignificant in children over 1 year old.

Conclusions

This study showed age-dependent associations of CD with asthma and FEW in offspring. Moreover, CD appeared to have an effect on the cellular immunity in infants, the disorder of which may contribute to the development of asthma in children.

Risk Factors Associated With Health Care Utilization in Preschool Recurrent Wheezers in a Tropical Environment

Introduction: The severity of wheezing episodes is related with the need for health services, but the factors associated with health care utilization in preschool recurrent wheezers in underdeveloped regions are unclear. Objective: To evaluate the factors associated with health care utilization in preschool recurrent wheezers in Cartagena, Colombia. Methods: One hundred twenty-seven recurrent wheezers (age 2-6 years old) who were admitted to the emergency room (ER) due to wheezing in a Pediatric reference hospital in Cartagena were included. Children were evaluated by means of questionnaires and classified according to the number of ER visits, need for hospitalization and history of intensive care unit (ICU) admission due to wheezing within the last year. Total serum IgE and specific IgE to house dust mite allergens (HDM) were measured by ImmunoCAP® and allergen sensitization was evaluated by skin prick tests (SPT). Results: The maternal report of nocturnal cough without fever in their children increased the risk to have ≥5 ER visits in the last year due to wheezing. The use of montelukast was negatively associated with hospitalization, while a history of pneumonia and lack of tap water, increased the risk of hospitalization due to wheezing. A history of bronchiolitis, family history of asthma, cohabiting with two or more siblings, passive exposure to smoke and lack of sewage facilities increased the risk of ICU admission due to wheezing. The presence of atopy evaluated by SPT reactivity, total IgE levels or specific IgE to HDM were not associated with health care utilization. We also found that seroprevalence of positive IgE (≥0.35 kU/L) was 27% to B. tropicalis and 20.3% to D. pteronyssinus but the prevalence of positive IgE sensitization to these allergens was below 2% and 8% when evaluated by SPT, respectively. Conclusions: Poverty indicators are associated with ICU admission in a group of preschool recurrent wheezers and should be considered as aggravating factors for wheezing. These factors must be systematically assessed in the medical approach in underdeveloped regions in the tropics. Nocturnal cough without fever is a symptom associated with frequent ER visits while atopy was not associated with health care utilization in preschool recurrent wheezers.

The effects of different parity and delivery mode on wheezing disorders in the children-a retrospective cohort study in Fujian, China

BACKGROUND

The relationship between childbirth delivery methods and the risk of wheezing in children remains controversial. Few studies have explored it under different maternal conditions.

OBJECTIVE

To explore the influence of childbirth delivery method on the onset of wheezing in children of different parity.

METHODS

A total of 21716 patients were included in this retrospective observational study. Multivariable logistic regression was used to analyze the relationship between childbirth delivery method and wheezing in children under 18 years of age in Fujian Province.

RESULTS

Wheezing differed statistically based on the child's sex, age, season of onset, parity, jaundice history, and feeding patterns (P < 0.05). After adjusting for confounding factors, in cases of parity greater than two, the risk of wheezing in cesarean section deliveries was higher than that in vaginal deliveries (OR: 1.107; 95% CI 1.010-1.214). In girls with parity greater than two (OR: 1.179; 95% CI 1.003-1.387) and normal-weight infants with parity greater than two (OR: 1.106; 95% CI 1.003-1.220), the risk of wheezing in cesarean section deliveries was higher. The interaction term between the mode of childbirth and parity was significant in girls (P = 0.014).

CONCLUSION

The method of childbirth delivery and parity are related to the risk of wheezing and may be relevant to gender and birth weight. Parity and gender have synergistic effects on wheezing.

Bacterial Mucosal Immunotherapy with MV130 Prevents Recurrent Wheezing in Children: A Randomized, Double-Blind, Placebo-controlled Clinical Trial

Rationale: Recurrent wheezing in children represents a severe public health concern. Wheezing attacks (WA), mainly associated with viral infections, lack effective preventive therapies. Objectives: To evaluate the efficacy and safety of mucosal sublingual immunotherapy based on whole inactivated bacteria (MV130) in preventing WA in children. Methods: A Phase 3 randomized, double-blind, placebo-controlled, parallel-group trial including a cohort of 120 children <3 years old with ⩾3 WA during the previous year was conducted. Children with a positive skin test to common aeroallergens in the area where the clinical trial was performed were excluded from the trial. Subjects received MV130 or placebo daily for 6 months. The primary endpoint was the number of WA within 1 year after the first dose comparing MV130 and placebo. Measurements and Main Results: There was a significant lower number of WA in MV130 versus the placebo group, 3.0 (interquartile range [IQR], 2.0-4.0) versus 5.0 (IQR, 3.0-7.0) (P < 0.001). As secondary outcomes, a decrease in the duration of WA and a reduction in symptoms and medication scores in the MV130 versus placebo group were found. No adverse events were reported related to the active treatment. Conclusions: Mucosal bacterial immunotherapy with MV130 shows safety and clinical efficacy against recurrent WA in children.Clinical trial registered with www.clinicaltrials.gov (NCT01734811).

Zhike pingchuan granules improve bronchial asthma by regulating the IL-6/JAK2/STAT3 pathway

The present study aimed to investigate the effects of zhike pingchuan granules (ZKPC) on bronchial asthma and the underlying mechanism. A bronchial asthma mouse model was established by aerosol inhalation of ovalbumin. The changes in lung pathomorphology were observed by hematoxylin and eosin staining. The levels of IL-1β, TNF-α and IL-6 in bronchoalveolar lavage fluid (BALF) and serum were detected by corresponding ELISA kits. Levels of reactive oxygen species, malondialdehyde and superoxide dismutase in lung tissues were analyzed using corresponding kits. The expression of proteins related to apoptosis and the IL-6/janus kinase 2 (JAK2)/STAT3 pathway was detected by western blot analysis. The results showed that ZKPC significantly restored the dry/wet ratio and alleviated lung pathomorphology of bronchial asthmatic mice. In addition, ZKPC inhibits inflammation, oxidative stress levels and cell apoptosis in bronchial asthmatic mice and also suppressed the IL-6/JAK2/STAT3 pathway. Fedratinib (a JAK2 inhibitor) further strengthened the alleviative effects of ZKPC on bronchial asthma. In conclusion, ZKPC improved bronchial asthma by suppressing the IL-6/JAK2/STAT3 pathway.

Breastfeeding and wheeze-related outcomes in high-risk infants: A systematic review and meta-analysis

BACKGROUND

The risk of wheezing is high in infancy and is heightened in infants with a family history of asthma/atopy. The role of breastfeeding in influencing respiratory health for these high-risk infants is unclear.

OBJECTIVES

To systematically appraise evidence for the association between breastfeeding and wheeze incidences and severity in high-risk infants.

METHODS

Studies identified through electronic databases and reference lists were eligible if they assessed breastfeeding and respiratory outcomes in infants with a family history of asthma/atopy. The primary outcome was wheeze incidences in the first year of life. Secondary outcomes were wheeze incidences in the first 6 months of life, indicators of wheeze severity (recurrent wheeze, health-care utilization, and medication use), and other wheeze-related outcomes [bronchiolitis, pneumonia, croup, and incidence of lower respiratory tract infection (LRTI)] up to 12 months old. Meta-analyses were conducted where possible.

RESULTS

Of 1843 articles screened, 15 observational studies met the inclusion criteria. Breastfeeding was associated with 32% reduced odds of wheezing during the first year of life (ever vs. never: OR, 0.68; 95% CI: 0.53, 0.88; n = 9 studies); this association was even stronger in the first 6 months (OR, 0.45; 95% CI: 0.27, 0.75; n = 5 studies). Breastfeeding for a "longer" versus "shorter" time (approximately longer vs. shorter than 3 months) was associated with 50% reduced odds of wheezing at the age of 6 months (OR, 0.50; 95% CI: 0.39, 0.64; n = 3 studies).

CONCLUSIONS

Breastfeeding was associated with reduced odds of wheezing in high-risk infants, with the strongest protection in the first 6 months. More research is needed to understand the impact of breastfeeding intensity on wheezing and to examine additional respiratory outcomes, including wheeze severity. This review was registered at PROSPERO as CRD42019118631.

Models for estimating and projecting global, regional and national prevalence and disease burden of asthma: a systematic review

Background

Statistical models are increasingly being used to estimate and project the prevalence and burden of asthma. Given substantial variations in these estimates, there is a need to critically assess the properties of these models and assess their transparency and reproducibility. We aimed to critically appraise the strengths, limitations and reproducibility of existing models for estimating and projecting the global, regional and national prevalence and burden of asthma.

Methods

We undertook a systematic review, which involved searching Medline, Embase, World Health Organization Library and Information Services (WHOLIS) and Web of Science from 1980 to 2017 for modelling studies. Two reviewers independently assessed the eligibility of studies for inclusion and then assessed their strengths, limitations and reproducibility using pre-defined quality criteria. Data were descriptively and narratively synthesised.

Results

We identified 108 eligible studies, which employed a total of 51 models: 42 models were used to derive national level estimates, two models for regional estimates, four models for global and regional estimates and three models for global, regional and national estimates. Ten models were used to estimate the prevalence of asthma, 27 models estimated the burden of asthma – including, health care service utilisation, disability-adjusted life years, mortality and direct and indirect costs of asthma – and 14 models estimated both the prevalence and burden of asthma. Logistic and linear regression models were most widely used for national estimates. Different versions of the DisMod-MR- Bayesian meta-regression models and Cause Of Death Ensemble model (CODEm) were predominantly used for global, regional and national estimates. Most models suffered from a number of methodological limitations – in particular, poor reporting, insufficient quality and lack of reproducibility.

Conclusions

Whilst global, regional and national estimates of asthma prevalence and burden continue to inform health policy and investment decisions on asthma, most models used to derive these estimates lack the required reproducibility. There is a need for better-constructed models for estimating and projecting the prevalence and disease burden of asthma and a related need for better reporting of models, and making data and code available to facilitate replication.

Prevalence of respiratory viruses using polymerase chain reaction in children with wheezing, a systematic review and meta-analysis

INTRODUCTION

Wheezing is a major problem in children, and respiratory viruses are often believed to be the causative agent. While molecular detection tools enable identification of respiratory viruses in wheezing children, it remains unclear if and how these viruses are associated with wheezing. The objective of this systematic review is to clarify the prevalence of different respiratory viruses in children with wheezing.

METHODS

We performed an electronic in Pubmed and Global Index Medicus on 01 July 2019 and manual search. We performed search of studies that have detected common respiratory viruses in children ≤18 years with wheezing. We included only studies using polymerase chain reaction (PCR) assays. Study data were extracted and the quality of articles assessed. We conducted sensitivity, subgroup, publication bias, and heterogeneity analyses using a random effects model.

RESULTS

The systematic review included 33 studies. Rhinovirus, with a prevalence of 35.6% (95% CI 24.6-47.3, I2 98.4%), and respiratory syncytial virus, at 31.0% (95% CI 19.9-43.3, I2 96.4%), were the most common viruses detected. The prevalence of other respiratory viruses was as follows: human bocavirus 8.1% (95% CI 5.3-11.3, I2 84.6%), human adenovirus 7.7% (95% CI 2.6-15.0, I2 91.0%), influenza virus6.5% (95% CI 2.2-12.6, I2 92.4%), human metapneumovirus5.8% (95% CI 3.4-8.8, I2 89.0%), enterovirus 4.3% (95% CI 0.1-12.9, I2 96.2%), human parainfluenza virus 3.8% (95% CI 1.5-6.9, I2 79.1%), and human coronavirus 2.2% (95% CI 0.6-4.4, I2 79.4%).

CONCLUSIONS

Our results suggest that rhinovirus and respiratory syncytial virus may contribute to the etiology of wheezing in children. While the clinical implications of molecular detection of respiratory viruses remains an interesting question, this study helps to illuminate the potential of role respiratory viruses in pediatric wheezing.

REVIEW REGISTRATION

PROSPERO, CRD42018115128.

Maternal asthma, breastfeeding, and respiratory outcomes in the first year of life

Maternal asthma increases the risk of infant wheeze. Breastfeeding may offer protection but there is limited evidence in this high-risk group. We examined associations between breastfeeding and respiratory outcomes, in infants born to women with asthma. This study was a secondary analysis of two prospective cohorts of pregnant women with asthma, and their infants, conducted between 2007 and 2018. At 6 ± 1 (T1) and 12 ± 1 (T2) months post-partum, mothers reported breastfeeding patterns and infant wheeze (primary outcome), bronchiolitis, and related medication use and healthcare utilization, via a validated questionnaire; a subgroup completed face-to-face interviews. χ² tests and logistic regression models, adjusting for confounders, were utilized. Data were complete for 605 participants at T1 and 486 (80%) at T2. Of 605 participants: 89% initiated breastfeeding and 38% breastfed for more than 6 months. Breastfeeding for more than 6 months vs "never" was associated with a reduced adjusted relative risk of infant wheeze at T1 (0.54, 95% confidence interval, 0.30-0.96). Bronchiolitis risk was reduced at T1 and T2 with more tha 6 months of breastfeeding vs "never." Breastfeeding duration of 1 to 3 months, 4 to 6 months, and more than 6 months were associated with a reduced risk of infant healthcare utilization (all P < .05, vs "never"), but not medication use (P > .05). Breastfeeding for more than 6 months was associated with a reduced risk of wheeze, bronchiolitis, and wheeze-related healthcare utilization in infants at risk due to maternal asthma. Notably, breastfeeding for shorter durations was associated with a reduced risk of healthcare utilization compared with none. Larger cohorts are needed to further examine the impact of breastfeeding exposure on respiratory health in infants exposed to maternal asthma.

A risk factor for early wheezing in infants: rapid weight gain

Background

The aim of this study was to investigate the correlation between rapid weight gain and early wheezing.

Methods

This study screened 701 infants with lower respiratory tract infection who were no more than 4 months from Jan 1st to Dec 31st in 2018. According to weight-for-age Z-value (WAZ), these infants were divided into the considerably slow weight gain group (group I), the normal weight gain group (group II) and the excessively rapid weight gain group (group III), respectively. The clinical characteristics, weight growth speeds and serum lipid levels were analyzed, and multivariable Logistic model was conducted to select significant variables.

Results

Our results showed that male (OR = 1.841, 95%CI: 1.233–2.751), family wheezing (OR = 5.118, 95%CI: 2.118–12.365), age (OR = 1.273, 95%CI: 1.155–1.403), eczema (OR = 2.769, 95%CI: 1.793–4.275), respiratory syncytial virus (RSV) infection (OR = 1.790, 95%CI: 1.230–2.604), birth weight (OR = 1.746, 95%CI: 1.110–2.746) and total cholesterol (TC) (OR = 1.027, 95%CI: 1.019–1.036) and ΔWAZ (OR = 1.182, 95%CI: 1.022–1.368) were associated with early wheezing. Results indicated that serum TC (P = 0.018) and ΔWAZ (P = 0.023) were positive correlation with wheezing days.

Conclusion

Besides male, family wheezing, age, eczema, RSV infection, birth weight and TC, the rapid weight growth as a risk factor should be concerned in the early wheezing infants.

Mediterranean diet during pregnancy and childhood for asthma in children: A systematic review and meta-analysis of observational studies

OBJECTIVES

To evaluate the relationship between high adherence to the Mediterranean diet in pregnancy and childhood and the risk of asthma and wheeze in children.

METHODS

We conducted searches of PubMed, EMBASE, and Cochrane Central Register of Controlled Trials from inception to 30 October 2018. Observational studies providing risk estimates and corresponding confidence intervals on the association of high adherence to the Mediterranean diet in pregnancy or childhood and the risk of asthma or wheeze in childhood were included. The methodological quality of all included studies was assessed. Summary odds ratios (OR) were calculated using a random-effects model.

RESULTS

Eighteen observational studies were included in this review. All studies were of moderate to high quality. The pooled data suggested high adherence to the Mediterranean diet during pregnancy was associated with a reduced incidence of wheeze in the first 12 months (OR, 0.92; 95% confidence interval [CI], 0.88-0.95; P < 0.001), and there was an inverse association between the Mediterranean diet during childhood and the incidence of wheeze in the history (OR, 0.51; 95% CI, 0.37-0.70; P = 0.001) and current wheeze (OR, 0.97; 95% CI, 0.95-0.99; P = 0.013). However, there was no significant association between high adherence of the Mediterranean diet in pregnancy and childhood and any of the other meta-analysis end points including diagnosed asthma.

CONCLUSION

High adherence to the Mediterranean diet during pregnancy and childhood may have short-term effects on wheeze in children in early life. However, these findings should be interpreted with caution owing to the heterogeneity of the studies.

Informing randomized clinical trials of respiratory syncytial virus vaccination during pregnancy to prevent recurrent childhood wheezing: A sample size analysis

BACKGROUND

Early RSV illness is associated with wheeze-associated disorders in childhood. Candidate respiratory syncytial virus (RSV) vaccines may prevent acute RSV illness in infants. We investigated the feasibility of maternal RSV vaccine trials to demonstrate reductions in recurrent childhood wheezing in general paediatric populations.

METHODS

We calculated vaccine trial effect sizes that depended on vaccine efficacy, allocation ratio, rate of early severe RSV illness, risk of recurrent wheezing at age 3, and increased risk of RSV infection on recurrent wheezing. Model inputs came from systematic reviews and meta-analyses. For each combination of inputs, we estimated the sample size required to detect the effect of vaccination on recurrent wheezing.

RESULTS

There were 81 scenarios with 1:1 allocation ratio. Risk ratios between vaccination and recurrent wheezing ranged from 0.9 to 1.0 for 70% of the scenarios. Among the 57 more plausible scenarios, the lowest sample size required to detect significant reductions in recurrent wheezing was 6196 mother-infant pairs per trial arm; however, 75% and 47% of plausible scenarios required >31,060 and >100,000 mother-infant pairs per trial arm, respectively. Studies with asthma endpoints at age 5 will likely need to be larger.

DISCUSSION

Clinical efficacy trials of candidate maternal RSV vaccines undertaken for licensure are unlikely to demonstrate an effect on recurrent wheezing illness due to the large sample sizes likely needed to demonstrate a significant effect. Further efforts are needed to plan for alternative study designs to estimate the impact of maternal RSV vaccine programs on recurrent childhood wheezing in general populations.

Effects of supplementation with omega-3 fatty acids during pregnancy on asthma or wheeze of children: a systematic review and meta-analysis

Objective: To evaluate the effects of omega-3 fatty acids during pregnancy on the incidence of wheeze and asthma of children.Methods: A search was conducted in PubMed, Embase and CENTRAL until September 2017. Randomized controlled trials (RCTs) assessing the effects of omega-3 fatty acids during pregnancy on wheeze/asthma of children were included. Two investigators independently searched articles, extracted data, and assessed the quality of included studies. Outcomes of relative risks were pooled. Subgroup analyses were conducted.Results: Seven RCTs involving 2047 children were included. The pooled data revealed the supplementation during pregnancy reduced the incidence of wheeze/asthma (risk ratio (RR) 0.81; 95% CI 0.66-0.99; p .04), but the incidence of childhood asthma was not significantly reduced (RR 0.89; 95% CI 0.67-1.17; p .40). Subgroup analyses indicated that the risk of childhood wheeze/asthma was significantly decreased (1) in studies located in Europe (RR 0.67 95% CI 0.51- 0.88), (2) in children whose first-degree relatives were diagnosed with allergic disease (RR 0.65 95% CI 0.49-0.85), (3) when a dose of omega -3 fatty acids ≥2000 mg/d was applied (RR 0.61 95% CI 0.45-0.81), (4) in wheeze/asthma without sensitivity (RR 0.71 95% CI 0.54-0.94).Conclusion: The available low-quality evidence indicated that omega-3 fatty acids supplementation during pregnancy may reduce the incidence of wheeze/asthma of children, but incidence of asthma was not reduced after omega-3 fatty acids supplementation during pregnancy. More well-designed RCTs with large sample sizes need to be conducted to better understand the effectiveness of omega-3 fatty acids supplementation during pregnancy with asthma in childhood.