Factors predicting persistence of early wheezing through childhood and adolescence: a systematic review of the literature

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.

Dysregulation of iron homeostasis in airways associated with persistent preschool wheezing

BACKGROUND

Currently, there are no reliable clinical tools available to identify persistent asthma symptoms among preschool children with recurrent wheezing. We investigated iron homeostasis in the airways of preschoolers with recurrent wheezing and assessed whether iron homeostasis-related indices may reliably predict persistent wheezing.

METHODS

Iron levels and mRNA expression levels of iron homeostasis molecules were examined in bronchoalveolar lavage samples from 89 preschoolers with recurrent wheezing and 56 controls, with a 12-month follow-up conducted. Risk factors for persistent wheezing were identified using least absolute shrinkage and selection operator and multivariate logistic regression. The addition of predictive values of iron indices to the modified Asthma Predictive Index (mAPI) or clinical predictors was determined using area under receiver operating characteristic curves (AUC).

RESULTS

Preschoolers with recurrent wheezing had reduced iron levels in their airways, associated with significantly decreased expression of iron export molecule SLC40A1 and increased expression of iron intake factor TFR1 and iron storage factors FTH and FTL. Risk factors for persistent wheezing included mAPI positivity, iron predictors (lower expression of SLC40A1 and higher expression of FTL), and clinical predictors (aeroallergen sensitivity, shorter breastfeeding duration, and earlier age of first wheezing episode). The addition of information on iron predictors significantly enhanced the power of clinical predictors (AUC: 84%, increase of 12%) and mAPI (AUC: 81%, increase of 14%).

CONCLUSIONS

Iron homeostasis is altered in the airways of preschoolers with recurrent wheezing. Adding information on iron-related indices to clinical information significantly improves accurate prediction of persistent wheezing in preschool-aged children.

Loss of control in preschoolers with asthma is a risk factor for disease persistency

AIM

To describe the relationship between loss of control events in preschoolers with asthma and persistence of disease.

METHODS

We reviewed medical records of children <6 years diagnosed with asthma in 2018 to assess loss of control events during three years of follow-up. Asthma persistency was defined by redeem of short-acting β2-agonist or asthma controllers within one year after the end of follow-up. Logistic regression models were applied to analyse the association between loss of control events and persistence of asthma.

RESULTS

We included 172 patients (median age 1.8 years), whereof 126 (73.3%) experienced a loss of control event and 87 (50.6%) had asthma one year after the end of follow-up. Any loss of control event was associated with persistence of asthma adjusted for controller treatment at inclusion, prior exacerbations, atopic comorbidity and caesarean section: aOR, 10.9 (95% CI, 3.9-34.6), p < 0.001. This was also significant restricted to events in the first year of follow-up: 3.52 (1.50-8.67), p < 0.01 and among children only experiencing one event: 6.4 (1.7-27.3), p = 0.01.

CONCLUSION

Loss of control events during a 3-year period among preschoolers with asthma are closely related to disease persistency, which may aid clinicians to assess risk of persistent asthma in young children.

A pilot study exploring the association of bronchial bacterial microbiota and recurrent wheezing in infants with atopy

Background

Differences in bronchial microbiota composition have been found to be associated with asthma; however, it is still unclear whether these findings can be applied to recurrent wheezing in infants especially with aeroallergen sensitization.

Objectives

To determine the pathogenesis of atopic wheezing in infants and to identify diagnostic biomarkers, we analyzed the bronchial bacterial microbiota of infants with recurrent wheezing and with or without atopic diseases using a systems biology approach.

Methods

Bacterial communities in bronchoalveolar lavage samples from 15 atopic wheezing infants, 15 non-atopic wheezing infants, and 18 foreign body aspiration control infants were characterized using 16S rRNA gene sequencing. The bacterial composition and community-level functions inferred from between-group differences from sequence profiles were analyzed.

Results

Both α- and β-diversity differed significantly between the groups. Compared to non-atopic wheezing infants, atopic wheezing infants showed a significantly higher abundance in two phyla (Deinococcota and unidentified bacteria) and one genus (Haemophilus) and a significantly lower abundance in one phylum (Actinobacteria). The random forest predictive model of 10 genera based on OTU-based features suggested that airway microbiota has diagnostic value for distinguishing atopic wheezing infants from non-atopic wheezing infants. PICRUSt2 based on KEGG hierarchy (level 3) revealed that atopic wheezing-associated differences in predicted bacterial functions included cytoskeleton proteins, glutamatergic synapses, and porphyrin and chlorophyll metabolism pathways.

Conclusion

The differential candidate biomarkers identified by microbiome analysis in our work may have reference value for the diagnosis of wheezing in infants with atopy. To confirm that, airway microbiome combined with metabolomics analysis should be further investigated in the future.

Persistent Asthma at School Age: Associated Factors in Preschool Children with Asthma

Most patients with childhood asthma present their first symptoms at preschool age. Identifying modifiable risks and protective factors at an early age may help develop asthma prevention and control strategies. This study aimed to identify factors at preschool age that are associated with persistent asthma at school age. This retrospective observational study included preschool children with asthma from 2015 to 2020 at a university hospital in Southern Thailand. In total, 189 eligible participants (70.9% boys; median age, 7.6 [6.7, 8.5] years) were included. Wheeze characteristics included early transient wheeze, persistent wheeze, and late-onset wheeze that accounted for 55%, 27.5%, and 19.5% of the patients, respectively. Approximately 20% of the participants had persistent asthma. Breastfeeding was a protective factor (odds ratio [OR] 0.4 [0.2, 0.9], p = 0.04). The modifiable risk factors were siblings living in the same household (OR 2.6 [1.1, 6.2], p = 0.02) and residence in an industrial area (OR 3.8 [1.4, 10.5], p = 0.009). Additionally, presence of allergic rhinitis was associated with an increased risk of persistent asthma at school age (OR 3.6 [1.6, 8.2], p = 0.002). Early therapeutic interventions targeting modifiable factors provide a window of opportunity to prevent persistent asthma at school age.

The role of epigenetics in multi-generational transmission of asthma: An NIAID workshop report-based narrative review

There is mounting evidence that environmental exposures can result in effects on health that can be transmitted across generations, without the need for a direct exposure to the original factor, for example, the effect of grandparental smoking on grandchildren. Hence, an individual's health should be investigated with the knowledge of cross-generational influences. Epigenetic factors are molecular factors or processes that regulate genome activity and may impact cross-generational effects. Epigenetic transgenerational inheritance has been demonstrated in plants and animals, but the presence and extent of this process in humans are currently being investigated. Experimental data in animals support transmission of asthma risk across generations from a single exposure to the deleterious factor and suggest that the nature of this transmission is in part due to changes in DNA methylation, the most studied epigenetic process. The association of father's prepuberty exposure with offspring risk of asthma and lung function deficit may also be mediated by epigenetic processes. Multi-generational birth cohorts are ideal to investigate the presence and impact of transfer of disease susceptibility across generations and underlying mechanisms. However, multi-generational studies require recruitment and assessment of participants over several decades. Investigation of adult multi-generation cohorts is less resource intensive but run the risk of recall bias. Statistical analysis is challenging given varying degrees of longitudinal and hierarchical data but path analyses, structural equation modelling and multilevel modelling can be employed, and directed networks addressing longitudinal effects deserve exploration as an effort to study causal pathways.

Bacterial composition and colony structure of the lower respiratory tract in infants and children with recurrent wheezing: a case-control study

BACKGROUND

The bacterial load of the human lower respiratory tract is at least several times lower than that of the other parts of the body. This study aimed to identify the bacterial composition and colony structure of the lower respiratory tract in infants and children with recurrent wheezing compared with those of children with a bronchial foreign body and clarify whether the length of wheezing in infants can contribute to differences in the lower respiratory tract's bacterial colony structure.

METHODS

We collected specimens of alveolar lavage fluid from 48 infants and children who underwent fiberoptic bronchoscopy and were divided into groups: A1 (multiple wheezing: wheezing more than three times in < 1 month), A2 (persistent wheezing: > 1 month), and B (bronchial foreign body; control group). We analyzed the bacterial community structure of alveolar lavage fluid using high-throughput sequencing. The richness and diversity of the microbial communities were assessed by α and β diversity analyses.

RESULTS

A total of 6,644 operational taxonomic units (OTUs) were obtained based on the Illumina Nova sequencing platform and clustered according to those that met the 97% identity threshold, followed by species annotation of the OTU sequences. In the annotation results, 2,608 (39.25%) OTUs were annotated at the genus level. At the genus level, Sphingomonas and Phyllobacterium were significantly higher in group A1 than in group B. There were significantly more Phyllobacterium in group A2 than in group B. Prevotella, Neisseria, and Haemophilus were higher in group B than in groups A1 and A2. The differences in the between-group α and β diversity analyses were statistically significant. The microbial diversity in groups A1 and A2 was significantly less than that in group B, but there was no statistical difference in bacterial community diversity between groups A1 and A2.

CONCLUSION

Recurrent wheezing in infants and children is more likely due to alterations in the overall bacterial microecology and disruption of host respiration and immune homeostasis than the effects of a single bacterium.

Prevalence and Determinants of Wheezing and Bronchodilatation in Children With Cystic Fibrosis: A Retrospective Cohort Study

Background

Many patients with cystic fibrosis (CF) wheeze, and are dubbed as having CF-asthma. Understanding the determinants of such wheezing may avoid unnecessary treatments and open newer treatment avenues.

Objectives

Main: To evaluate the prevalence and characteristics of wheezing and a positive bronchodilatory response (BDR) in children with CF. Secondary: To identify the predictive markers and the impact of current wheezing a positive BDR.

Methods

A retrospective single-center study in children with CF. We determined the characteristics of physician-reported wheeze in patients <6 years, and a BDR in patients aged 6-17 years. Anthropometric, lung function, laboratory, genetic and microbiological data were recorded in all groups. Variables were compared using the Chi2 and Student t-tests, and ANOVA.

Results

125 preschool and 69 school-aged children and adolescents with CF were included in the study. 71.2% of patients <6 years of age had had at least one episode of wheezing: 26.3% of patients were Transient Early Wheezers, 12.6% Late Onset Wheezers and 37.9% were Persistent Wheezers. The prevalence of a positive BDR was 73.5, 48.5, and 52.9% in the 6-8 years, 10-12 years, and 15-17 years age groups, respectively. Allergic factors were not predictive of wheezing in preschoolers. In the 6-8 years age group, the sum of wheal diameters of allergic skin prick tests (SPT, house dust mite + cat + dog dander) was greater in those with a BDR vs. no BDR (4 [2.0-8.8] vs. 1 [0-7.0] mm, p = 0.01). The presence of Pseudomonas aeruginosa in the bronchial secretions before 3 years of age was not significantly associated with either the presence of wheezing at the age of 6 years or a BDR in school-aged children and adolescents. The proportion of homozygous p.F508del patients was significantly lower in the group of patients who had wheezed by 6 years of age (60% vs. 72.7%, p = 0.009), but higher in the 6-8 years old group with a BDR vs. no BDR (64% vs. 36%, p = 0.04). Current wheezers at 6 years had a lower mean FEV1 vs. the non-current wheezers (91.5 ± 4.4% vs. 100.9 ± 2.4%; p = 0.047). Similarly, forced vital capacity (FVC) was significantly lower in the 6-8 years old group with BDR vs. no BDR (85 ± 19 vs. 101 ± 21%, p = 0.015).

Conclusion

Wheezing and BDR are very frequent findings in children with CF. Current wheeze at the age of 6 years was associated with worse lung function. Labeling wheezing in CF as "CF-Asthma" is misleading since the determinants are different, and may lead to inappropriate prescriptions of inhaled steroids.

Prevalence of infantile wheezing and eczema in a metropolitan city in Japan: A complete census survey

Infantile wheezing and eczema are associated with the subsequent onset of asthma and other atopic diseases. However, there are no large population-based surveys on infantile allergic symptoms in Japan. The objective of the study was to determine the prevalence of wheezing and asthma in infants in Nagoya, Japan. This population-based cross-sectional study was performed in the metropolitan city of Nagoya, Japan. We surveyed parents to ascertain the prevalence of wheezing and eczema in infants who attended group health checkups at 3, 18, and 36 months of age. Their parents completed modified questionnaires from the International Study of Asthma and Allergies in Childhood. More than 90% of the approximately 40,000 children in each study group living in the target area were included in the survey. The prevalence of wheezing was 8%, 17%, and 13% at 3, 18, and 36 months, respectively, and was characterized by birth season. The prevalence of eczema was 24%, 30%, and 31%, at 3, 18, and 36 months, respectively. Participants born in autumn and winter had a higher incidence of eczema in each age group. Three-quarters of the children had a parental history of allergic conditions. Parental allergic diseases and male gender are risk factors for wheezing and eczema in children. This survey had a high response rate and covered almost the entire population of the target age groups in a large city. We believe that the results of this study, therefore, provide a much higher level of confidence regarding the prevalence of allergies in infants in Japan than that in previous studies with limited cohorts.

Factors associated with resolution of childhood asthma by the age of 17: Large cohort analysis

BACKGROUND

Many children with asthma will become asymptomatic during adolescence. In this study, we evaluated factors associated with recovery from asthma by the age of 17.

METHODS

The medical records of 17-year-old conscripts to the Israeli army with asthma were compared with the records of conscripts with rigorously diagnosed resolved asthma. We assessed the association between the following parameters and asthma resolution: body mass index (BMI), recurrent rhinitis, birth season, socioeconomic level, and cognition.

RESULTS

Sixty-eight thousand and ninety conscripts with active asthma were compared to 14,695 with resolved asthma. In univariate analysis, rhinitis, overweight, underweight, higher socioeconomic level, and lower cognitive score were associated with active asthma (p < 0.001 for both sexes), but not the season of birth. In multivariate analysis, only overweight, underweight, rhinitis, and lower cognitive score (p < 0.001 for both sexes) remained significantly associated with persistence of asthma.

CONCLUSIONS

Although association does not prove causation, our finding is another reason to encourage adolescents with asthma to maintain a normal body weight. Prospective interventional studies are needed in order to decide whether changing weight to ensure BMI is within the ideal range and controlling rhinitis increases the odds of resolution of asthma in adolescence.

The impact of a digital wheeze detector on parental disease management of pre-school children suffering from wheezing-a pilot study

BACKGROUND

Viral airway infections are a major reason for doctor's visits at pre-school age, especially when associated with wheezing. While proper treatment requires adequate recognition of airway obstruction, caretakers are often struggling with this judgment, consequently leading to insufficient or late treatment and an unnecessary discomfort of the patient. Digital technologies may serve to support parental decision taking. The aim of the present pilot study is to acquire data on the feasibility of recruitment and observation procedures for a randomized controlled trial on the impact of a digital wheeze detector in a home management setting of pre-school wheezing.

METHODS

This single-armed pilot study enrolled patients with a doctor's diagnosis of wheezing aged 9 to 72 months. Participants were asked to use a digital wheeze detector (WheezeScan, Omron Healthcare, Japan) 2×/day for 30 days and record the child's respiratory symptoms, detection of wheezing, and medication intake via an electronic diary (eDiary) app. Demographic and clinical data were collected at the recruitment visit. The asthma control test and the Parent Asthma Management Self-Efficacy Scale (PAMSES) were assessed both, at recruitment and follow-up.

RESULTS

Twenty families were recruited and completed the monitoring. All but one completed the follow-up after 30 days. The recruitment procedures were feasible, and adherence to daily monitoring reached an average of 81%. The use of the wheeze detector was rated as uncomplicated. Parents detected wheezing without digital support in only 22/708 (3.1%) of the recorded events. By contrast, the wheeze detector indicated an airway obstruction in 140/708 (19.8%) of the recordings.

CONCLUSION

In parallel to feasible recruitment procedures, we observed good usability of the wheeze detection device and high adherence to eDiary recording. The positive outcomes show that the WheezeScan may empower parents by increasing their capacity for wheeze detection. This deserves to be investigated in a larger randomized controlled trial.

Rhinovirus Infection and Familial Atopy Predict Persistent Asthma and Sensitisation 7 Years after a First Episode of Acute Bronchiolitis in Infancy

Background: We set out to assess the risk factors for asthma outcome in a cohort of infants who experienced their first episode of acute bronchiolitis. Methods: A cohort of 222 infants who were included during a first episode of acute bronchiolitis was prospectively followed. Herein, we present the results of their assessments (symptom history, skin prick tests, specific IgE assay, respiratory function tests) at age seven. Results: Of the 68/222 (30.6%) children assessed at age seven, 15 (22.05%) presented with asthma and were mainly males (p = 0.033), 14 (20%) had respiratory allergies, 17 (25%) presented atopic dermatitis and none had a food allergy. Family history of atopy was associated with asthma and sensitisation to aeroallergens at age seven (p = 0.003, p = 0.007). Rhinovirus (hRV) infection and rhinovirus/respiratory syncytial virus (RSV) co-infection were significantly associated with asthma at age seven (p = 0.035, p = 0.04), but not with the initial severity of bronchiolitis. Eosinophil counts at ages three and seven were significantly higher in the asthmatics (p = 0.01, p = 0.046). Conclusion: Any infant, especially male, presenting a first episode of acute bronchiolitis due to hRV with a family history of atopy should be closely monitored via follow-up due to a higher risk for asthma at school age.

The role of atopy in asthma development and persistence

PURPOSE OF REVIEW

Asthma is the most common chronic disease in pediatric age. Childhood-onset asthma, as opposed to adult-onset asthma, is typically characterized by a personal and often a family history of atopy and related markers of type 2-mediated inflammation. However, the interplay between atopy and asthma development is more complex than a linear dose-response relationship.

RECENT FINDINGS

Family and personal history of atopic diseases have been confirmed as major risk factors for asthma occurrence and persistence in children. Early life and multiple sensitizations to aeroallergens significantly increase the risk of asthma development in school age. Early life lower respiratory tract viral infections, especially caused by rhinovirus, also increase the susceptibility to atopic asthma in childhood. Human rhinovirus type C receptor CDHR3 polymorphisms have been shown to affect receptor epithelial expression, activation, and asthma development and exacerbation severity in children. Atopic sensitization and respiratory viral infections can synergistically enhance the susceptibility to asthma through multiple mechanisms, including the IgE-mediated inhibition of innate antiviral responses to rhinovirus. Emerging evidence shows that several nonatopic factors are also involved in the asthma pathogenesis in genetically predisposed individuals, including early life exposure to environmental factors, and lung and gut microbiome composition.

SUMMARY

The current review outlines recent data on the complex role of atopy in asthma pathogenesis and persistence, and addresses new research topics such as the role of epigenetics and the lung microbiome.

A model of perinatal stress and childhood wheezing: ELSPAC-CZ cohort

BACKGROUND

Prenatal origins of wheezing are not fully understood. This study develops a model of mechanisms linking perinatal stress exposure to wheeze phenotypes in children.

METHODS

Data were obtained from 1880 mother-child dyads participating in ELSPAC-CZ birth cohort. Wheeze phenotypes assessed between birth and age 7 years included "never wheeze," "early-onset transient (EOT) wheeze," "early-onset persistent (EOP) wheeze," and "late-onset (LO) wheeze." Prenatal and postnatal stress exposures were assessed in mid-pregnancy and 6 months after delivery, respectively, using an inventory of 42 life events.

RESULTS

In adjusted models, children in the highest tercile (high) versus lowest tercile (low) for prenatal life events had a 38% higher risk of EOT wheeze (relative risk ratio [RRR] = 1.38; 95% confidence interval [CI] = 1.01-1.88; p = .041) and 50% higher risk of LO wheeze (RRR = 1.50; 95% CI = 1.00-2.25; p = .047). High versus low exposure to postnatal life events predicted a 60% increase in relative risk of EOT wheeze (RRR = 1.60; 95% CI = 1.17-2.19; p = .003) and medium versus low exposure was related to an 85% increase in relative risk of EOP wheeze (RRR = 1.85; 95% CI = 1.16-2.95; p = .010). Lower respiratory tract infections and postpartum depression partially mediated between postnatal life events and any wheeze (indirect effects 1.06, 95% CI = 1.02-1.09, p = .003 and odds ratio [OR] = 1.08, 95% CI = 1.02-1.15, p = .012, respectively), while postnatal events mediate for prenatal events (indirect effect OR = 1.11; 95% CI = 1.03-1.18; p = .005).

CONCLUSIONS

Exposures to prenatal and postnatal life events are risk factors for the development of wheezing. Prenatal stress contributes to wheeze directly and also through postnatal life events, respiratory infections, and maternal depression.

Association between asthma control trajectories in preschoolers and disease remission

INTRODUCTION

Early disease morbidity has been associated with asthma persistence in wheezing preschoolers; however, whether asthma control trajectories shortly after diagnosis could influence remission is unknown. We examined the association between asthma control trajectories 2 years post-diagnosis in preschoolers and subsequent disease remission.

METHODS

We conducted a multicentre population-based retrospective cohort study consisting of 48 687 children with asthma diagnosed before 5 years old and born between 1990 and 2013 in four Canadian provinces who had prolonged disease activity post-diagnosis. Prolonged disease activity was defined as one or more medical visits or medications for asthma every 6-month period for at least four of the six periods post-diagnosis. Follow-up began at 3 years post-diagnosis (at cohort entry). Remission was defined as 2 consecutive years without drug claims or medical visits for asthma or asthma-like conditions following cohort entry. Asthma control trajectories, ascertained over four 6-month periods following diagnosis using a validated index, were classified as: "controlled throughout", "improving control", "worsening control", "out of control throughout" and "fluctuating control". Adjusted Cox models estimated associations between asthma control trajectories and time to remission. A random effects meta-analysis summarised province-specific hazard ratios (HRs).

RESULTS

The pooled remission rate was 8.91 (95% CI 8.80-9.02) per 100 person-years. Compared with children controlled throughout, poorer asthma control was associated with incrementally lower hazard ratios of remission in four other trajectories: improving control (HR 0.89, 95% CI 0.82-0.96), fluctuating control (HR 0.78, 95% CI 0.71-0.85), worsening control (HR 0.68, 95% CI 0.62-0.75) and out of control throughout (HR 0.52, 95% CI 0.45-0.59).

CONCLUSIONS

Asthma control trajectories 2 years following a diagnosis in preschoolers were associated with remission, highlighting the clinical relevance of documenting control trajectories in early life.

Burden of preschool wheeze and progression to asthma in the UK: Population-based cohort 2007 to 2017

BACKGROUND

Wheeze is one of the most common symptoms of preschool children (age 1-5 years), yet we have little understanding of the burden in the United Kingdom.

OBJECTIVES

We sought to determine prevalence and pattern of physician-confirmed preschool wheeze, related health care utilization, and factors associated with progression to school-age asthma.

METHODS

We used nationally representative primary and secondary care electronic medical records between 2007 and 2017 to identify preschool children with wheeze. Factors associated with asthma progression were identified in a nested cohort of children with follow-up from age 1 to 2 years, until at least age 8 years.

RESULTS

From 1,021,624 preschool children, 69,261 were identified with wheeze. Prevalence of preschool wheeze was 7.7% in 2017. Wheeze events were lowest in August and highest in late-autumn/early-winter. During median follow-up of 2 years (interquartile range, 1.2-4.0 years), 15.8% attended an emergency department, and 13.9% had a hospital admission, for a respiratory disorder. The nested cohort with prolonged follow-up identified 15,085 children; 35.5% progressed to asthma between age 5 and 8 years. Of children with preschool wheeze, without an asthma diagnosis, 34.9% were prescribed inhaled corticosteroids and 15.6% oral corticosteroids. The factors most strongly associated with progression to asthma were wheeze frequency and severity, atopy, prematurity, maternal asthma severity, and first reported wheeze event occurring in September.

CONCLUSIONS

Preschool wheeze causes considerable health care burden, and a large number of children are prescribed asthma medication and have unplanned secondary care visits. Multiple factors influence progression to asthma, including first wheeze event occurring in September.

Prevalence of Skin Reactions and Self-Reported Allergies in 5 Countries with Their Social Impact Measured through Quality of Life Impairment

Background: The prevalence of allergies increases worldwide. Allergies may increase the risk of skin reactions. Objective: To evaluate the prevalence of allergies and skin reactions in the adult population, the strength of their relationship, and their impact on the quality of life. Methods: An online survey was conducted in a representative population of 11,067 adults from China, USA, Brazil, Russia, and France. Results: Overall, 35.6% of respondents reported having allergies, they were predominantly fair-skinned women, and younger than responders reporting no allergy. Among patients reporting allergies, 68.6% declared that their allergy makes their skin reacts. A strong association between allergy and major skin reactions was observed, which were associated with skin discomforts such as itching, burning, and pain. Skin discomforts were associated with an increased risk of quality of life alteration. Conclusions: Quantifying the prevalence and the association of allergies with skin reactions and discomfort sensations is critical to evaluating the impact on quality of life. Since skin barrier alteration is hypothesized as a risk factor and a route of sensitization for allergy development, the daily use of topical treatments, such as moisturizers, could help prevent allergic skin reactions, discomfort and impaired quality of life in individuals with an altered skin barrier.

Personalized prediction of early childhood asthma persistence: A machine learning approach

Early childhood asthma diagnosis is common; however, many children diagnosed before age 5 experience symptom resolution and it remains difficult to identify individuals whose symptoms will persist. Our objective was to develop machine learning models to identify which individuals diagnosed with asthma before age 5 continue to experience asthma-related visits. We curated a retrospective dataset for 9,934 children derived from electronic health record (EHR) data. We trained five machine learning models to differentiate individuals without subsequent asthma-related visits (transient diagnosis) from those with asthma-related visits between ages 5 and 10 (persistent diagnosis) given clinical information up to age 5 years. Based on average NPV-Specificity area (ANSA), all models performed significantly better than random chance, with XGBoost obtaining the best performance (0.43 mean ANSA). Feature importance analysis indicated age of last asthma diagnosis under 5 years, total number of asthma related visits, self-identified black race, allergic rhinitis, and eczema as important features. Although our models appear to perform well, a lack of prior models utilizing a large number of features to predict individual persistence makes direct comparison infeasible. However, feature importance analysis indicates our models are consistent with prior research indicating diagnosis age and prior health service utilization as important predictors of persistent asthma. We therefore find that machine learning models can predict which individuals will experience persistent asthma with good performance and may be useful to guide clinician and parental decisions regarding asthma counselling in early childhood.

Childhood wheeze trajectory-specific risk factors: A systematic review and meta-analysis

BACKGROUND

There is growing interest in the use of latent trajectory methodology to identify wheeze patterns in heterogeneous populations of children. This study systematically reviewed and meta-analyzed childhood wheeze trajectory studies to identify childhood wheeze trajectory group-specific risk factors among children from birth through to adolescence.

METHODS

We included studies that used latent trajectory methodology to identify wheeze trajectories and associated risk factors. We searched PubMed, EMBASE, and Google Scholar from 2000 through September 30, 2019, for relevant studies. The study was conducted according to the PRISMA recommendations.

RESULTS

Thirteen cohort studies conducted in eleven high-income countries were included in our meta-analysis with the length of follow-up ranging from 3 to 18 years. Five distinct latent wheeze trajectory groups were identified: Never/Infrequent, Early-Transient, Early-Persistent, Intermediate-Onset, and Late-Onset. We found moderate-to-strong evidence that family history of asthma predicted persistent childhood wheezing among male children but with lower risk among first-born children. There was weak-to-moderate evidence for childhood atopy, male sex, short duration of breastfeeding, tobacco exposure, daycare attendance, and having siblings as risk factors for Early-Transient wheezing; except for breastfeeding, these factors were also associated with intermediate and Late-Onset wheezing with varying effect sizes in high-risk vs general population cohorts.

CONCLUSIONS

Our findings confirm the consistency of wheeze trajectory groups defined by onset, peak prevalence, and duration; we also suggest a common nomenclature for future trajectory studies. With the exception of the relationship between a family history of asthma and persistent childhood wheezing, commonly suspected wheeze risk factors (childhood atopy, male sex, short duration of breastfeeding, tobacco exposure, daycare attendance, and having siblings) are not trajectory-specific and have varying effects in high-risk vs general population cohorts. Delineation of time-varying risk factor effects may be critical to the specificity of wheeze trajectory group prediction to better inform prognosis and targeted early preventive intervention among at-risk children.

Can serum periostin, YKL-40, and osteopontin levels in pre-school children with recurrent wheezing predict later development of asthma?

BACKGROUND

Currently, there are no reliable clinical tools available for predicting asthma in pre-school-aged children with recurrent wheezing. The aim of this study was to evaluate the usefulness of serum periostin, YKL-40, and osteopontin biomarkers in wheezy pre-school-aged children for predicting the development of asthma in school ages.

METHODS

The study was prospectively conducted between 2011 and 2017. The clinical features of the pre-school-aged children with recurrent wheezing and the levels of serum periostin, YKL-40, and osteopontin were measured. The same participants were reevaluated in school-age period, and participants with asthma were identified. Relative risk (RR) for the development of asthma was analyzed.

RESULTS

Of the 197 pre-school-aged children with recurrent wheezing who were reevaluated in school-age years, 32% of them had asthma. Serum periostin, YKL-40, and osteopontin levels at admission could not predict participants who would have asthma symptoms in school-age years. The RR for continuing of asthma symptoms was higher in participants who had their first wheezing episode before 1 year of age, preterm birth, cesarean section delivery, prenatal smoking exposure, multi-trigger wheezing, parental asthma, modified asthma predictive index positivity, prophylactic vitamin D intake ≤ 12 months, breastfeeding time ≤ 12 month, and aeroallergen sensitivity [RR (95% CI) and P value: 2.813 (1.299-6.091), 0.002; 1.972 (1.274-3.052), 0.009; 1.929 (1.195-3.114), 0.004; 2.232 (1.463-3.406), <0.001; 3.152 (1.949-5.097), <0.001; 1.730 (1.144-2.615), 0.016; 2.427 (1.559-3.777), <0.001; 2.955 (1.558-5.604), <0.001; 1.767 (1.084-2.881), 0.016; 0.765 (0.556-1.053), 0.016; respectively].

CONCLUSION

Results have shown that clinical features were more valuable than biomarkers in predicting having asthma in school-age years in participants who had recurrent wheezing in pre-school-age period.

Variability in Diagnosed Asthma in Young Children in a Large Pediatric Primary Care Network

OBJECTIVE

Our objectives were to 1) quantify the frequency of wheezing episodes and asthma diagnosis in young children in a large pediatric primary care network and 2) assess the variability in practice-level asthma diagnosis, accounting for common asthma risk factors and comorbidities. We hypothesized that significant variability in practice-level asthma diagnosis rates would remain after adjusting for associated predictors.

METHODS

We generated a retrospective longitudinal birth cohort of children who visited 1 of 31 pediatric primary care practices within the first 6 months of life from 1/2005 to 12/2016. Children were observed for up to 8 years or until the end of the observation window. We used multivariable discrete time survival models to evaluate predictors of asthma diagnosis by 3-month age intervals. We compared unadjusted and adjusted proportions of children diagnosed with asthma by practice.

RESULTS

Of the 161,502 children in the cohort, 34,578 children (21%) received at least 1 asthma diagnosis. In multivariable modeling, male gender, minority race/ethnicity, gestational age <34 weeks, allergic rhinitis, food allergy, and prior wheezing episodes were associated with asthma diagnosis. After adjusting for variation in these predictors across practices, the cumulative incidence of asthma diagnosis by practice by age 6 years ranged from 11% to 47% (interquartile range: 24%-29%).

CONCLUSIONS

Across pediatric primary care practices, adjusted incidence of asthma diagnosis by age 6 years ranged widely, though variation gauged by the interquartile range was more modest. Potential sources of practice-level variation, such as differing diagnosis thresholds and labeling of different wheezing phenotypes as "asthma," should be further investigated.

Efficacy of treatment with montelukast, fluticasone propionate and budesonide liquid suspension for the prevention of recurrent asthma paroxysms in children with wheezing disorders

One-third of the children who suffer from first-time wheezing are estimated to experience recurrences; however, no standard therapeutic strategy with which to prevent these recurrences currently exists. A few studies have compared the three drugs commonly used for the treatment of persistent asthma in children to identify the most effective one for preventing recurrent wheezing. In this study, in an aim to determine the most effective of these drugs, we recruited patients <5 years of age with recurrent wheezing at our hospital, and assigned them randomly to either the oral montelukast [leukotriene receptor antagonist (LTRA)], the inhaled fluticasone propionate (FP), or the inhaled budesonide suspension (BUD) groups for 12-week treatments. We then determined the treatment efficacy (symptomatic improvement) by recording the number of wheezing episodes and emergency visits, the daily treatment cost, the mean accumulated down time and the patient compliance; we then compared the results among the groups. All treatments were found to be equally effective. The daily cost of inhaled FP was lower than that of oral LTRA and inhaled BUD (P<0.00001). The difference in the mean accumulated down time between these groups was not significant (P=0.132). The adherence (patient compliance) to LTRA was significantly higher than the adherence to inhaled corticosteroids (ICS) (P<0.017). On the whole, the findings of this study indicated that all three treatments prevented recurrent wheezing in our pediatric population. FP was found to be more convenient, to require fewer doses, and that it could be easily adjusted. Patient adherence/compliance to treatment was significantly better with LTRA than with ICS.

Risk factors and prognosis of recurrent wheezing in Chinese young children: a prospective cohort study

Background

Nearly all the investigations into the risk factors for wheezing and asthma were conducted in developed countries with a high prevalence rate of asthma and allergy, but the studies in developing countries are limited. In this study, we aimed to investigate the risk factors for different wheezing phenotypes in Chinese young children and to explore the prognosis of recurrent wheezing.

Methods

This cohort study contained the recruitment stage and the follow-up stage conducted by phone questionnaire survey. According to the information collected at the follow-up for wheezing episodes and remission age, our cohort was divided into transient wheezing, persistent wheezing and late-onset wheezing. The wheezing symptoms and potential risk factors were compared between these three wheezing groups.

Results

From the initial 109 participants, 78.0% completed the follow-up survey. The frequency of current wheezing at followup was significantly reduced in all three groups compared to the recruitment stage (p < 0.01). We observe a trend that the rhinovirus (RV) and respiratory syncytial virus (RSV) infection rates were higher in the persistent wheezing group, and the overall infection rates appear to be the lowest in late-onset wheezing group at recruitment. At follow-up stage, the rates of rhinitis ever and current rhinitis were both higher in the persistent wheezing (63.0%, 50.0%) and late-onset wheezing groups (88.2%, 58.8%), compared to the transient wheezing group (14.3%, 14.3%). The incidence of current wheezing episodes increased cumulatively if the participant had concomitant risk factors of rhinitis ever, aeroallergens sensitization at recruitment, either alone or together with previous RV infection at the time of recruitment.

Conclusion

While the incidence of wheezing declined overall with age, but in addition to transient wheezers, additional subsets of children manifest persistent wheeze or late onset wheeze, and moreover the risk factors for wheezing display phenotypic variability between these subgroups. Rhinitis ever and aeroallergens sensitization, either alone or together with previous RV infection, were the most significant predictors for persistent wheezing in children in an eastern environment, such as in China.

Validation of childhood asthma predictive tools: A systematic review

BACKGROUND

There is uncertainty about the clinical usefulness of currently available asthma predictive tools. Validation of predictive tools in different populations and clinical settings is an essential requirement for the assessment of their predictive performance, reproducibility and generalizability. We aimed to critically appraise asthma predictive tools which have been validated in external studies.

METHODS

We searched MEDLINE and EMBASE (1946-2017) for all available childhood asthma prediction models and focused on externally validated predictive tools alongside the studies in which they were originally developed. We excluded non-English and non-original studies. PROSPERO registration number is CRD42016035727.

RESULTS

From 946 screened papers, eight were included in the review. Statistical approaches for creation of prediction tools included chi-square tests, logistic regression models and the least absolute shrinkage and selection operator. Predictive models were developed and validated in general and high-risk populations. Only three prediction tools were externally validated: the Asthma Predictive Index, the PIAMA and the Leicester asthma prediction tool. A variety of predictors has been tested, but no studies examined the same combination. There was heterogeneity in definition of the primary outcome among development and validation studies, and no objective measurements were used for asthma diagnosis. The performance of tools varied at different ages of outcome assessment. We observed a discrepancy between the development and validation studies in the tools' predictive performance in terms of sensitivity and positive predictive values.

CONCLUSIONS

Validated asthma predictive tools, reviewed in this paper, provided poor predictive accuracy with performance variation in sensitivity and positive predictive value.

Comparison of the Associations of Early-Life Factors on Wheezing Phenotypes in Preterm-Born Children and Term-Born Children

Although respiratory symptoms, including wheezing, are common in preterm-born subjects, the natural history of the wheezing phenotypes and the influence of early-life factors and characteristics on phenotypes are unclear. Participants from the Millennium Cohort Study who were born between 2000 and 2002 were studied at 9 months and at 3, 5, 7, and 11 years. We used data-driven methods to define wheezing phenotypes in preterm-born children and investigated whether the association of early-life factors and characteristics with wheezing phenotypes was similar between preterm- and term-born children. A total of 1,049/1,502 (70%) preterm-born children and 12,307/17,063 (72%) term-born children had recent wheeze data for 3 or 4 time points. Recent wheeze was more common at all time points in the preterm-born group than in term-born group. Four wheezing phenotypes were defined for both groups: no/infrequent, early, persistent, and late. Early-life factors and characteristics, especially antenatal maternal smoking, atopy, and male sex, were associated with increased rates for all phenotypes in both groups, and breastfeeding was protective in both groups, except late wheeze in the preterm group. Preterm-born children had similar phenotypes to term-born children. Although early-life factors and characteristics were similarly associated with the wheezing phenotypes in both groups, the preterm-born group had higher rates of early and persistent wheeze. However, a large proportion of preterm-born children had early wheeze that resolved with time.

Immunological Processes Driving IgE Sensitisation and Disease Development in Males and Females

IgE sensitisation has increased significantly over the last decades and is a crucial factor in the development of allergic diseases. IgE antibodies are produced by B cells through the process of antigen presentation by dendritic cells, subsequent differentiation of CD4⁺ Th2 cells, and class switching in B cells. However, many of the factors regulating these processes remain unclear. These processes affect males and females differently, resulting in a significantly higher prevalence of IgE sensitisation in males compared to females from an early age. Before the onset of puberty, this increased prevalence of IgE sensitisation is also associated with a higher prevalence of clinical symptoms in males; however, after puberty, females experience a surge in the incidence of allergic symptoms. This is particularly apparent in allergic asthma, but also in other allergic diseases such as food and contact allergies. This has been partly attributed to the pro- versus anti-allergic effects of female versus male sex hormones; however, it remains unclear how the expression of sex hormones translates IgE sensitisation into clinical symptoms. In this review, we describe the recent epidemiological findings on IgE sensitisation in male and females and discuss recent mechanistic studies casting further light on how the expression of sex hormones may influence the innate and adaptive immune system at mucosal surfaces and how sex hormones may be involved in translating IgE sensitisation into clinical manifestations.

Classification of Pediatric Asthma: From Phenotype Discovery to Clinical Practice

Advances in big data analytics have created an opportunity for a step change in unraveling mechanisms underlying the development of complex diseases such as asthma, providing valuable insights that drive better diagnostic decision-making in clinical practice, and opening up paths to individualized treatment plans. However, translating findings from data-driven analyses into meaningful insights and actionable solutions requires approaches and tools which move beyond mining and patterning longitudinal data. The purpose of this review is to summarize recent advances in phenotyping of asthma, to discuss key hurdles currently hampering the translation of phenotypic variation into mechanistic insights and clinical setting, and to suggest potential solutions that may address these limitations and accelerate moving discoveries into practice. In order to advance the field of phenotypic discovery, greater focus should be placed on investigating the extent of within-phenotype variation. We advocate a more cautious modeling approach by "supervising" the findings to delineate more precisely the characteristics of the individual trajectories assigned to each phenotype. Furthermore, it is important to employ different methods within a study to compare the stability of derived phenotypes, and to assess the immutability of individual assignments to phenotypes. If we are to make a step change toward precision (stratified or personalized) medicine and capitalize on the available big data assets, we have to develop genuine cross-disciplinary collaborations, wherein data scientists who turn data into information using algorithms and machine learning, team up with medical professionals who provide deep insights on specific subjects from a clinical perspective.

Biomarkers in inflammometry pediatric asthma: utility in daily clinical practice

Asthma is a common disease in both high and lower income countries that starts early and persists often for life. A correct and accurate diagnosis, treatment and follow-up during childhood are essential for a better understanding of adult asthma and avoiding over- or under-treatment. Th2 inflammation in children with asthma symptoms is usually assessed by measuring with serum total IgE, blood eosinophilia and FeNO levels that may help to predict asthma, particularly in those infants and young children in whom lung function tests are difficult to perform. FeNO measurement, compared to intra-individual levels, may be useful also for ascertaining treatment adherence. Nevertheless, an isolated measurement may be insufficient and only the combination of these markers improves the diagnosis, phenotyping and follow-up of an asthmatic child.

Differences between preschoolers with asthma and allergies in urban and rural environments

OBJECTIVE

Previous studies have provided conflicting results about how living in a rural or urban environment influences schoolchildren with asthma and allergic diseases in different ways. The aim of the present study was to evaluate if recurrent wheezing preschoolers from rural or urban areas differ in asthma, allergic diseases, and atopy.

METHODS

A cross-sectional-study in Rafaela, Argentina, on 143 preschoolers with recurrent wheezing from rural and urban settings was performed (2010-2012). Diagnosis of asthma (by positive asthma predictive index [API]), allergic diseases (rhinitis, dermatitis), and atopy (by skin prick test [SPT], peripheral blood eosinophils, and serum total IgE) were assessed.

RESULTS

Preschoolers from rural settings had significantly higher prevalence of vaginal delivery, longer breastfeeding, earlier onset of wheezing, more parental smoking, siblings, shared a bedroom, and more exposure to chemicals used in plant fumigation or farm animals, and unpasteurized milk consumption, in comparison to preschoolers living in urban setting. In contrast, preschoolers from urban areas had significantly higher prevalence of parental history of allergy, positive skin prick test, and positive API. After multivariate analysis adjusting for covariates, maternal smoking [odds ratio (OR) = 3.44] and positive SPT (OR = 5.57) significantly increase the risk of asthma diagnosis (positive API); in contrast, living in rural setting (OR = 0.04), and having more siblings (OR = 0.51) decrease their risk.

CONCLUSIONS

Recurrent wheezing preschoolers from rural areas had a significant inverse odds of being diagnosed with asthma (type-2 inflammation) when compared to those from urban areas. Exposure to farm animals and consumption of unpasteurized milk might have a role.

The Role of Sensitization to Allergen in Asthma Prediction and Prevention

The burden of asthma in childhood is considerable worldwide, although some populations are much more affected than others. Many attempts have been made by different investigators to identify the factors that could predict asthma development or persistence in childhood. In this review, the relation between atopic sensitization as an indicator of allergy and asthma in childhood will be discussed. Cross sectional studies, carried out in different countries, failed to show any firm correlation between asthma and atopic sensitization. Birth cohort mainly of infants at high risk for asthma and case-control studies showed that atopic sensitization was a risk factor for current asthma in children older than 6 years. In general, clear relations are observed mostly in affluent Western countries, whereas in less affluent countries, the picture is more heterogeneous. For the prediction of asthma development or persistence in school age children, other prerequisites should also be fulfilled such as family history of asthma and wheezing episodes at preschool age. Despite the conductance of different studies regarding the potential role of allergen avoidance for the primary prevention of childhood asthma, it does not seem that this approach is of benefit for primary prevention purposes. However, the identification of children at risk for asthma is of benefit as these subjects could be provided with the best management practices and with the appropriate secondary prevention measures.