Risk factors for asthma after infant bronchiolitis

The impact of exposure to tobacco smoke and e-cigarettes on asthma-related outcomes: Systematic review informing the EAACI guidelines on environmental science for allergic diseases and asthma

To inform the clinical practice guidelines' recommendations developed by the European Academy of Allergy and Clinical Immunology systematic reviews (SR) assessed using GRADE on the impact of environmental tobacco smoke (ETS) and active smoking on the risk of new-onset asthma/recurrent wheezing (RW)/low lung function (LF), and on asthma-related outcomes. Only longitudinal studies were included, almost all on combustion cigarettes, only one assessing e-cigarettes and LF. According to the first SR (67 studies), prenatal ETS increases the risk of RW (moderate certainty evidence) and may increase the risk of new-onset asthma and of low LF (low certainty evidence). Postnatal ETS increases the risk of new-onset asthma and of RW (moderate certainty evidence) and may impact LF (low certainty evidence). Combined in utero and postnatal ETS may increase the risk of new-onset asthma (low certainty evidence) and increases the risk of RW (moderate certainty evidence). According to the second SR (24 studies), ETS increases the risk of severe asthma exacerbations and impairs asthma control and LF (moderate certainty evidence). According to the third SR (25 studies), active smoking increases the risk of severe asthma exacerbations and of suboptimal asthma control (moderate certainty evidence) and may impact asthma-related quality-of-life and LF (low certainty evidence).

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

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

Clinical characteristics and differential cytokine expression in hospitalized Taiwanese children with respiratory syncytial virus and rhinovirus bronchiolitis

BACKGROUND

Viral bronchiolitis presents a heterogeneous spectrum. In this study, we investigated the clinical characteristics and the cytokines/chemokines profiles among respiratory syncytial virus (RSV), rhinovirus (RV), and their dual infection in Taiwanese children with viral bronchiolitis.

METHOD

This study was conducted between October 2014 and June 2017. Viral etiology was identified using a Luminex respiratory virus panel and blood cytokines were evaluated using a MILLIPLEX MAP Human Cytokine/Chemokine Panel. Cytokine/Chemokine expressions were compared by clinical severity, steroid treatment, and viral entities.

RESULTS

A total of 184 patients were evaluated; at least one respiratory virus was identified in 163 (88.6%) patients. RSV and RV were the two leading viral etiologies, with 25.5% and 17.3%, respectively. RV bronchiolitis has a comparable severity to RSV but is more common in children of an older age with a history of recurrent wheezing and blood eosinophilia. Decreased tumor necrosis factor-alpha (TNF-α) and interferon gamma (INF-γ) levels were correlated with clinical severity. Patients infected with RV exhibited higher levels of Interleukin (IL)-22, IL-23, IL-25, IL-31, and IL-33 (p < 0.05), whereas those with RSV had higher levels of TNF-α, INF-γ, and IL-10 (p < 0.05). Systemic steroid treatment was associated with higher expressions of IL-4, IL-8, IL-13, and MIP-1α levels (p < 0.05). Cluster analysis revealed a high correlation of IL-33 and IL-31(R² = 0.9731, p < 0.0001).

CONCLUSION

Different viral infections elicited the characteristic clinical presentation and immune profiles in bronchiolitis. Our findings also highlight the role of the IL-33/IL-31 axis in the immunopathogenesis of bronchiolitis.

Respiratory Syncytial Virus-Specific Antibodies and Atopic Diseases in Children: A 10-Year Follow-Up

Background: Respiratory syncytial virus (RSV) stimulates the production of specific immunoglobulin (Ig) E and IgG4 antibodies as a hallmark of the Th2 immune response. In this paper, we evaluated the occurrence of atopic diseases in 10-year-old children who were positive for RSV-specific IgG antibodies during infancy. Methods: The prospective follow-up of 72 children included a physical examination, an International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and the determination of RSV-specific antibodies and total and allergen-specific IgE. Results: Children with asthma had their first wheezing episode at a younger age (χ2 8.097, df = 1, p = 0.004). RSV-specific IgG4 levels at year one were positively correlated with atopic dermatitis (AD) (tau_b = 0.211, p = 0.049) and current AD (tau_b = 0.269, p = 0.012); and RSV-specific IgE levels were positively correlated with allergic rhinitis (AR) (tau_b = 0.290, p = 0.012) and current AR (tau_b = 0.260, p = 0.025). Positive RSV-specific IgE at the age of one increased the chances of asthma occurrence by 5.94 (OR = 5.94, 95% CI = 1.05–33.64; p = 0.044) and the chances of AR by more than 15 times (OR = 15.03, 95% CI = 2.08–108.72; p = 0.007). A positive family history of atopy increased the chances of asthma occurrence by 5.49 times (OR = 5.49, 95% CI = 1.01–30.07; p = 0.049), and a longer duration of exclusive breastfeeding lowered that chance (OR = 0.63, 95% CI = 0.45–0.89; p = 0.008). Prenatal smoking increased the chances of AR occurrence by 7.63 times (OR = 7.63, 95% CI = 1.59–36.53; p = 0.011). Conclusion: RSV-specific IgE and RSV-specific IgG4 antibodies could be risk markers for the development of atopic diseases in children.

Nasopharyngeal lipidomic endotypes of infants with bronchiolitis and risk of childhood asthma: a multicentre prospective study

BACKGROUND

Bronchiolitis is the leading cause of hospitalisation of US infants and an important risk factor for childhood asthma. Recent evidence suggests that bronchiolitis is clinically heterogeneous. We sought to derive bronchiolitis endotypes by integrating clinical, virus and lipidomics data and to examine their relationship with subsequent asthma risk.

METHODS

This is a multicentre prospective cohort study of infants (age <12 months) hospitalised for bronchiolitis. We identified endotypes by applying clustering approaches to clinical, virus and nasopharyngeal airway lipidomic data measured at hospitalisation. We then determined their longitudinal association with the risk for developing asthma by age 6 years by fitting a mixed-effects logistic regression model. To account for multiple comparisons of the lipidomics data, we computed the false discovery rate (FDR). To understand the underlying biological mechanism of the endotypes, we also applied pathway analyses to the lipidomics data.

RESULTS

Of 917 infants with bronchiolitis (median age, 3 months), we identified clinically and biologically meaningful lipidomic endotypes: (A) cinicalclassiclipidmixed (n=263), (B) clinicalseverelipidsphingolipids-high (n=281), (C) clinicalmoderatelipidphospholipids-high (n=212) and (D) clinicalatopiclipidsphingolipids-low (n=161). Endotype A infants were characterised by 'classic' clinical presentation of bronchiolitis. Profile D infants were characterised by a higher proportion of parental asthma, IgE sensitisation and rhinovirus infection and low sphingolipids (eg, sphingomyelins, ceramides). Compared with endotype A, profile D infants had a significantly higher risk of asthma (22% vs 50%; unadjusted OR, 3.60; 95% CI 2.31 to 5.62; p<0.001). Additionally, endotype D had a significantly lower abundance of polyunsaturated fatty acids (eg, docosahexaenoic acid; FDR=0.01). The pathway analysis revealed that sphingolipid metabolism pathway was differentially expressed in endotype D (FDR=0.048).

CONCLUSIONS

In this multicentre prospective cohort study of infants with bronchiolitis, integrated clustering of clinical, virus and lipidomic data identified clinically and biologically distinct endotypes that have a significantly differential risk for developing asthma.Delete.

Proteomics endotyping of infants with severe bronchiolitis and risk of childhood asthma

BACKGROUND

Bronchiolitis is the leading cause of hospitalization in U.S. infants and a major risk factor for childhood asthma. Growing evidence supports clinical heterogeneity within bronchiolitis. We aimed to identify endotypes of infant bronchiolitis by integrating clinical, virus, and serum proteome data, and examine their relationships with asthma development.

METHODS

This is a multicenter prospective cohort study of infants hospitalized for physician-diagnosis of bronchiolitis. We identified bronchiolitis endotypes by applying unsupervised machine learning (clustering) approaches to integrated clinical, virus (respiratory syncytial virus [RSV], rhinovirus [RV]), and serum proteome data measured at hospitalization. We then examined their longitudinal association with the risk for developing asthma by age 6 years.

RESULTS

In 140 infants hospitalized with bronchiolitis, we identified three endotypes: (1) clinicalatopic virusRV proteomeNFκB-dysregulated , (2) clinicalnon-atopic virusRSV/RV proteomeTNF-dysregulated , and (3) clinicalclassic virusRSV proteomeNFκB/TNF-regulated endotypes. Endotype 1 infants were characterized by high proportion of IgE sensitization and RV infection. These endotype 1 infants also had dysregulated NFκB pathways (FDR < 0.001) and significantly higher risks for developing asthma (53% vs. 22%; adjOR 4.04; 95% CI, 1.49-11.0; p = 0.006), compared with endotype 3 (clinically resembling "classic" bronchiolitis). Likewise, endotype 2 infants were characterized by low proportion of IgE sensitization and high proportion of RSV or RV infection. These endotype 2 infants had dysregulated tumor necrosis factor (TNF)-mediated signaling pathway (FDR <0.001) and significantly higher risks for developing asthma (44% vs. 22%; adjOR 2.71; 95% CI, 1.03-7.11, p = 0.04).

CONCLUSION

In this multicenter cohort, integrated clustering of clinical, virus, and proteome data identified biologically distinct endotypes of bronchiolitis that have differential risks of asthma development.

Respiratory virus type to guide predictive enrichment approaches in the management of the first episode of bronchiolitis: A systematic review

It has become clear that severe bronchiolitis is a heterogeneous disease; even so, current bronchiolitis management guidelines rely on the one-size-fits-all approach regarding achieving both short-term and chronic outcomes. It has been speculated that the use of molecular markers could guide more effective pharmacological management and achieve the prevention of chronic respiratory sequelae. Existing data suggest that asthma-like treatment (systemic corticosteroids and beta2-agonists) in infants with rhinovirus-induced bronchiolitis is associated with improved short-term and chronic outcomes, but robust data is still lacking. We performed a systematic search of PubMed, Embase, Web of Science, and the Cochrane’s Library to identify eligible randomized controlled trials to determine the efficacy of a personalized, virus-dependent application of systemic corticosteroids in children with severe bronchiolitis. Twelve studies with heterogeneous methodology were included. The analysis of the available results comparing the respiratory syncytial virus (RSV)-positive and RSV-negative children did not reveal significant differences in the associatons between systemic corticosteroid use in acute episode and duration of hospitalization (short-term outcome). However, this systematic review identified a trend of the positive association between the use of systematic corticosteroids and duration of hospitalization in RSV-negative infants hospitalized with the first episode of bronchiolitis (two studies). This evidence is not conclusive. Taken together, we suggest the design for future studies to assess the respiratory virus type in guiding predictive enrichment approaches in infants presenting with the first episode of bronchiolitis.

Association of Nasopharyngeal and Serum Glutathione Metabolism with Bronchiolitis Severity and Asthma Risk: A Prospective Multicenter Cohort Study

Infants hospitalized for bronchiolitis are at high risk for asthma. Glutathione-related metabolites may antagonize oxidative stress, which induces airway injuries in respiratory infection and subsequent airway remodeling. However, little is known about the relationship of glutathione-related metabolites with bronchiolitis severity and the risk of asthma. In a multicenter prospective observational cohort study of infants hospitalized for bronchiolitis, we measured nasopharyngeal and serum glutathione-related metabolites by using liquid chromatography−tandem mass spectrometry. We then examined their association with bronchiolitis severity (defined by positive pressure ventilation (PPV) use). We also identified severity-related glutathione-related metabolite signatures and examined their association with asthma at age 6 years. In 1013 infants, we identified 12 nasopharyngeal and 10 serum glutathione-related metabolites. In the multivariable models, lower relative abundances of seven metabolites, e.g., substrates of glutathione, including cysteine (adjOR 0.21, 95%CI 0.06−0.76), glycine (adjOR 0.25, 95%CI 0.07−0.85), and glutamate (adjOR 0.25, 95%CI 0.07−0.88), were significantly associated with PPV use (all FDR < 0.05). These associations were consistent with serum glutathione-related metabolites. The nasopharyngeal glutathione-related metabolite signature was also associated with a significantly higher risk of asthma (adjOR 0.90, 95%CI 0.82−0.99, p = 0.04). In infants hospitalized for bronchiolitis, glutathione-related metabolites were associated with bronchiolitis severity and asthma risk.

Association of Growth Trajectory Profiles with Asthma Development in Infants Hospitalized with Bronchiolitis

BACKGROUND

Little is known about the relationship of longitudinal growth trajectory in early life with asthma development, particularly in infants with bronchiolitis (a high-risk population).

OBJECTIVE

Among infants with bronchiolitis, we aimed to identify growth trajectory profiles and determine their longitudinal relationship with the risk for developing childhood asthma.

METHODS

A multicenter prospective study enrolled infants (aged <1 year) hospitalized for bronchiolitis. We identified growth trajectory profiles-derived from body mass index-for-age at ages 0, 6, 12, 15, 18, 24, and 36 months by using a longitudinal clustering method. We examined associations between growth trajectory profiles and asthma development by age 5 years.

RESULTS

The analytic cohort consists of 880 infants hospitalized for bronchiolitis (median age, 3 months). Overall, 26% developed asthma by age 5 years. The longitudinal clustering identified 5 distinct profiles: persistent low growth (27%), normative growth (33%), transient overweight (21%), late-onset overweight (16%), and persistent obesity (3%) profiles. In multivariable model, compared with children with a normative profile, those with a persistent obesity profile had significantly higher risks of developing asthma (24% vs 38%, odds ratio [OR]: 2.55, 95% confidence interval [CI]: 1.07-6.09, P = .03). Among children with a persistent obesity profile, those without allergic predisposition had significantly higher risks of asthma (OR: 3.02, 95% CI: 1.05-8.64, P = .04 in the nonparental allergic history group; OR: 3.18, 95% CI: 1.02-9.92, P = .047 in the non-IgE sensitization group), whereas those with allergic predisposition were not at increased risk.

CONCLUSIONS

This multicenter cohort study of infants with bronchiolitis demonstrated distinct growth trajectory profiles that have differential risks for developing asthma.

Interleukin 1 receptor-like 1 rs13408661/13431828 polymorphism is associated with persistent post-bronchiolitis asthma at school age

Aim

Interleukin (IL) 1 receptor‐like 1, encoded by the IL1RL1 gene, is a receptor for IL‐33. In European birth cohorts, IL1RL1 rs102082293, rs10204137 (rs4988955), rs13424006 and rs13431828 (rs13048661) variations were associated with asthma at school age. In a Dutch multi‐centre study, IL1RL1 rs1921622 variation was associated with severe bronchiolitis. We evaluated the associations of these five IL1RL1 variations with asthma and lung function at school age after hospitalisation for bronchiolitis in infancy.

Methods

Follow‐up data, including impulse oscillometry at age 5–7 and flow‐volume spirometry at age 11–13 years, and the IL1RL1 genotype data were available for 141 children followed until 5–7 and for 125 children followed until 11–13 age years after bronchiolitis in infancy. The IL1RL1 rs10204137 and rs4988955, and the IL1RL1 rs13048661 and rs13431828, are 100% co‐segregating in the Finnish population.

Results

The variant IL1RL1 rs13048661/13431828 genotype was constantly associated with increased asthma risk by various definitions at 5–7 and 11–13 years of ages. The result was confirmed with analyses adjusted for current confounders and early‐life environment‐related factors. Statistical significances were lost, when maternal asthma and atopic dermatitis in infancy were included in the model.

Conclusion

IL1RL1 rs13048661/13431828 variation was associated with post‐bronchiolitis asthma outcomes at school age.

Serum periostin among infants with severe bronchiolitis and risk of developing asthma: A prospective multicenter cohort study

BACKGROUND

Infants hospitalized for bronchiolitis (severe bronchiolitis) are at high risk for developing childhood asthma. However, the pathobiological link between these conditions remains unclear. We examined the longitudinal relationship of periostin (an extracellular matrix protein upregulated in response to type 2 inflammation) during bronchiolitis with the subsequent development of asthma.

METHODS

In a 17-center prospective cohort study of infants (aged <1 year) with severe bronchiolitis, we measured the serum periostin level at hospitalization and grouped infants into 3 groups: low, intermediate, and high levels. We examined their association with asthma development by age 6 years and investigated effect modification by allergic predisposition (eg, infant's IgE sensitization).

RESULTS

The analytic cohort consists of 847 infants with severe bronchiolitis (median age, 3 months). Overall, 28% developed asthma by age 6 years. In the multivariable model adjusting for nine patient-level factors, compared to the low periostin group, the asthma risk was significantly higher among infants in the intermediate group (23% vs. 32%, OR 1.68, 95%CI 1.12-2.51, p = .01) and non-significantly higher in the high-level group (28%, OR 1.29, 95%CI 0.86-1.95, p = .22). In the stratified analysis, infants with IgE sensitization had a significantly higher risk for developing asthma (intermediate group, OR 4.76, 95%CI 1.70-13.3, p = .002; high group, OR 3.19, 95%CI 1.08-9.36, p = .04). By contrast, infants without IgE sensitization did not have a significantly higher risk (p > .15).

CONCLUSIONS

In infants with severe bronchiolitis, serum periostin level at bronchiolitis hospitalization was associated with asthma risk by age 6 years, particularly among infants with an allergic predisposition.

Integrative genetics-metabolomics analysis of infant bronchiolitis-childhood asthma link: A multicenter prospective study

Background

Infants with bronchiolitis are at high risk for developing childhood asthma. While genome-wide association studies suggest common genetic susceptibilities between these conditions, the mechanisms underlying the link remain unclear.

Objective

Through integrated genetics-metabolomics analysis in this high-risk population, we sought to identify genetically driven metabolites associated with asthma development and genetic loci associated with both these metabolites and asthma susceptibility.

Methods

In a multicenter prospective cohort study of infants hospitalized for bronchiolitis, we profiled the nasopharyngeal metabolome and genotyped the whole genome at hospitalization. We identified asthma-related metabolites from 283 measured compounds and conducted metabolite quantitative trait loci (mtQTL) analyses. We further examined the mtQTL associations by testing shared genetic loci for metabolites and asthma using colocalization analysis and the concordance between the loci and known asthma-susceptibility genes.

Results

In 744 infants hospitalized with bronchiolitis, 28 metabolites (e.g., docosapentaenoate [DPA], 1,2-dioleoyl-sn-glycero-3-phosphoglycerol, sphingomyelin) were associated with asthma risk. A total of 349 loci were associated with these metabolites-161 for non-Hispanic white, 120 for non-Hispanic black, and 68 for Hispanics. Of these, there was evidence for 30 shared loci between 16 metabolites and asthma risk (colocalization posterior probability ≥0.5). The significant SNPs within loci were aligned with known asthma-susceptibility genes (e.g., ADORA1, MUC16).

Conclusion

The integrated genetics-metabolomics analysis identified genetically driven metabolites during infancy that are associated with asthma development and genetic loci associated with both these metabolites and asthma susceptibility. Identifying these metabolites and genetic loci should advance research into the functional mechanisms of the infant bronchiolitis-childhood asthma link.

Environmental risk factor assessment for major respiratory disorders in metropolitan cities of India using VIIRS Suomi Aerosol data and Google Trends

This study has investigated the association between the amount of atmospheric aerosols and the occurrences of Asthma, Chronic Obstructive Pulmonary Disease (COPD) and Lung Cancer in Delhi, Mumbai, Chennai, Kolkata and Bengaluru. Aerosol Optical Thickness (AOT) data of Visible Infrared Imaging Radiometer Suite (VIIRS) and Google Trends (GT) have been used to acquire information regarding the abundance of atmospheric aerosols and the occurrences of the respiratory diseases respectively. The result of Granger causality test between AOT and GT has shown that Delhi, Mumbai and Chennai were quite vulnerable to the three respiratory diseases whereas Bengaluru did not display so much vulnerability to these ailments. Kolkata was not so much vulnerable to Asthma but did exhibit susceptibility to the other two diseases. GT is validated by correlating with Annual Morbidity data of Delhi. The result of Granger causality test between Particulate Matter (diameter ≤ 10 μm) (PM10) data and GT validates the result of Granger causality between AOT and GT, and shows the trustworthiness of GT and AOT. Thus, this study also proves the usefulness of VIIRS AOT and GT as dependable sources of information on atmospheric aerosols and prevalence of the respiratory diseases respectively, and the effectiveness of Granger causality test as a tool of analysis in health and geographic information systems (GIS).

Toll-interacting protein polymorphisms in viral bronchiolitis outcomes

BACKGROUND

Toll-interacting protein is a key factor in regulating innate immunity responses via gatekeeping Toll-like receptors. Genetic variance in innate immunity has been linked with susceptibility to infections. Children with viral bronchiolitis in infancy are at increased risk of later asthma. The aim was to evaluate the role of toll-interacting protein gene point mutations in severity of bronchiolitis and subsequent risk of asthma.

METHODS

Infants less than 6 months old were recruited during hospitalization due to bronchiolitis. In all, 166 children were prospectively followed up to age of 1.5, 6, and 11 years. Clinical data on viral etiology and severity markers, and further post-bronchiolitis asthma and lung function outcomes were compared with genetic differences in two single-nucleotide point mutations rs116938768 and rs5743854 in the toll-interacting protein gene.

RESULTS

Toll-interacting protein rs116938768 or rs5743854 did not show significant associations with severity markers or viral etiology of bronchiolitis. Follow-up data on current asthma or lung function at 6 or 11 years of age after bronchiolitis were not associated with the investigated mutations.

CONCLUSION

Toll-interacting protein gene point mutations in rs116938768 or rs5743854 were not involved with the clinical course of viral bronchiolitis in early infancy, and did not predict post-bronchiolitis asthma or lung function reduction by the age of 11 years.

Risk factors for irreversible airway obstruction after infant bronchiolitis

BACKGROUND

Increasing evidence shows that environmental factors in childhood play a role in development of irreversible airway obstruction. We evaluated early-life and preschool-age risk factors for irreversible airway obstruction in adolescence after bronchiolitis in infancy.

METHODS

This study is a secondary analysis of data collected during prospective long-term follow-up of our post-bronchiolitis cohort. Risk factor data were collected during hospitalisation and on follow-up visits at 5-7 and 10-13 years of ages. Lung function was measured from 103 participants with impulse oscillometry at 5-7 years of age and from 89 participants with flow-volume spirometry at 10-13 years of age.

RESULTS

Asthma diagnosis at <12 months of age showed a significant association with irreversible airway obstruction at 10-13 years of age independently from current asthma. Irreversible airway obstruction was less frequent in children with variant than wild genotype of the Toll-like receptor 4(TLR4) rs4986790, but the significance was lost in logistic regression adjusted for current asthma and weight status. Higher post-bronchodilator respiratory system resistance at 5 Hz and lower baseline and post-bronchodilator reactance at 5 Hz by impulse oscillometry at 5-7 years of age were associated with irreversible airway obstruction at 10-13 years of age.

CONCLUSION

Asthma diagnosis during the first living year and worse lung function at preschool age increased the risk for irreversible airway obstruction at 10-13 years of age after bronchiolitis. TLR4 rs4986790 polymorphism may be protective for development of irreversible airway obstruction after bronchiolitis.

Prevalence and associated factors of wheeze in early infancy

BACKGROUND

The aim of this study was to assess the prevalence of wheeze in early childhood and to characterize associated factors for wheeze that could identify potentially feasible interventions for the future prevention of wheeze.

METHODS

We performed a cross-sectional analysis of the data from the International Study of Asthma and Allergies in Childhood (ISAAC)-modified self-administered questionnaire of parents of 4-month-old infants at well-child visits (mandatory health check-ups) in Nagoya City, Japan, between April 2016 and March 2017 (development dataset) and between April 2017 and March 2018 (validation dataset). We used a multivariable, multilevel analysis to identify significant (P < 0.05), associated factors (Bonferroni correction was applied as necessary) after adjustment for local outbreaks of virus-transmitted diseases, access to medical facilities, and socioeconomic status.

RESULTS

Among the 20 362 questionnaires given to families of infants living in Nagoya City (development dataset), 19 104 questionnaires (93.8%) were analyzed after data cleaning. In all, 1,446 (7.6%) infants experienced wheeze at least once within 4 months of age, 991 (5.2%) visited the clinic/hospital with wheeze, and 244 (1.3%) underwent hospitalization at that time. In the multilevel, multivariable model for hospitalization with wheeze, significant associated factors were male sex (adjusted odds ratio 1.8; 95% confidence interval 1.4-2.3), maternal current smoking (3.3; 2.0-5.5), and having at least one sibling (3.0; 2.2-4.1). These factors were also associated with wheeze and clinic/hospital visit with wheeze, and the results were confirmed in the validation dataset.

CONCLUSIONS

Our study highlights that smoking cessation among mothers and improved hand hygiene at home are two interventions that could potentially decrease wheeze in early infancy.

Association between early bronchiolitis and the development of childhood asthma: a meta-analysis

OBJECTIVE

Early life bronchiolitis has been hypothesised to be associated with the subsequent risk of persistent wheezing or asthma. However, the link remains controversial. The objective of our study was to evaluate the association between bronchiolitis before 2 years of age and the late-onset wheezing/asthma.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, Embase and Web of Science databases were systematically searched for studies published between 1955 and January 2020. Meanwhile, we also checked through the reference lists of relevant articles to see whether these references included reports of other studies that might be eligible for the review. Cohort and case-control studies assessing the association between early-life bronchiolitis and late-onset wheezing/asthma were included in this meta-analysis. Data were extracted by two independent reviewers. Results were pooled using a random-effects model or fixed-effects model according to the heterogeneity among studies.

RESULTS

32 original articles with 292 844 participants, which met the criteria, were included in this meta-analysis. Bronchiolitis before 2 years of age was associated with an increased risk of subsequent wheezing/asthma (relative risk=2.46, 95% CI 2.14 to 2.82, p<0.001). After categorising studies into different groups based on age at the end of follow-up, geographical region and study quality, the association still remained significant.

CONCLUSIONS

The meta-analysis indicates an association between bronchiolitis before 2 years of age and the wheezing/asthma in later life. Well-designed and highly standardised prospective studies that better address bias due to potential confounding factors are needed to validate the risk identified in our meta-analysis.PROSPERO registration numberCRD42018089453.

Interleukin-1 receptor-associated kinase-4 gene variation may increase post-bronchiolitis asthma risk

AIM

Evidence based on studies of the encoding genes suggests that interleukin-1 receptor-associated kinase-4 (IRAK4) plays a role in childhood asthma and allergy. Our aim was to evaluate the associations of six IRAK4 gene polymorphisms with presence of asthma and allergic rhinitis and use of inhaled corticosteroids (ICSs) for asthma at 5-7 and 11-13 years of ages after hospitalisation for bronchiolitis at younger than 6 months of age.

METHODS

IRAK4 rs4251513, rs4251520, rs4251522, rs4251578, rs79154645 and rs13852554 polymorphisms were determined in 141 former bronchiolitis patients prospectively followed up until 5-7 and in 125 children until 11-13 years of age.

RESULTS

The homozygous variant IRAK4 rs4251513 genotype was associated with the presence of asthma and allergic rhinitis and use of ICSs at 5-7 and 11-13 years of ages in univariate analyses. Statistical significance remained for the presence of asthma and use of ICSs but was lost in the case of allergic rhinitis in multivariate analyses. The adjusted odds ratios were 3.48 and 4.16 for asthma and 5.22 and 14.00 for ICS use at these two ages.

CONCLUSION

The homozygous variant IRAK4 rs4251513 genotype was constantly associated with post-bronchiolitis asthma and asthma medication in school-aged children.

Rhinovirus bronchiolitis, maternal asthma, and the development of asthma and lung function impairments

BACKGROUND

Children with a history of rhinovirus (RV) positive bronchiolitis have a high risk of developing subsequent asthma. Maternal asthma might also increase this risk. The aim of this study was to investigate the combined effects of hospitalization for RV positive bronchiolitis in infancy and a history of maternal asthma on the development of asthma at preschool age.

METHODS

This is a prospective cohort study of 139 preschool-aged children, with a history of hospital admission for bronchiolitis in infancy, followed-up to ascertain asthma and asthma-like symptoms, skin prick allergy test positivity, and lung function measured pre- and post-bronchodilator using impulse oscillometry.

RESULTS

Children with a past hospitalization for RV positive bronchiolitis (42.4% of all) and a history of maternal asthma (36.7% of all) had the greatest prevalence and risk ratio (RR) for doctor-diagnosed asthma (prevalence 81.8% and RR 2.10, 95% confidence interval [CI] 1.37-3.19, p = .001), use of inhaled corticosteroids (68.2% and RR 2.17, 95% CI 1.19-3.99, p = .001) and short-acting β-agonists in the last 12 months (95.2% and RR 1.49, 95% CI 1.17-1.89, p = .001), as compared to those with RV negative bronchiolitis and no maternal asthma history. More children in this group had an abnormal airway resistance (33.3% and adjusted risk ratio [aRR] 3.11, 95% CI 1.03-9.47, p = .045) and reactance (27.8% and aRR 2.11, 95% CI 1.06-4.26, p = .035) at 5 Hz, as compared to those with RV negative bronchiolitis and no maternal asthma history.

CONCLUSION

Hospitalization for RV positive bronchiolitis in early life combined with a history of maternal asthma identifies a subgroup of children with a high asthma burden while participants with only one of the two risk factors had intermediate risk for asthma.

IL17RA variations showed no associations with post-bronchiolitis asthma or lung function

BACKGROUND

Interleukin-17A (IL-17A) and IL-17F are involved in the pathogenesis of asthma and allergy. Interleukin-17 receptor A (IL-17RA), encoded by the IL17RA gene, is a common receptor for IL-17A and IL-17F. The aim of the present study was to evaluate the association of IL17RA gene variations with asthma, allergy, and lung function at school age in children prospectively followed up after hospitalization for bronchiolitis in early infancy.

METHODS

Data on IL17RA rs4819553, rs4819554, and rs4819558 polymorphisms and clinical outcomes, including asthma and allergic rhinitis, were available for 145 former bronchiolitis patients at 5-7 years and for 125 at 11-13 years of age. One hundred children underwent impulse oscillometry at 5-7 years and 84 underwent flow-volume spirometry at 11-13 years of age. The IL17RA rs4819553, rs4819554 and rs4819558 were completely co-segregating in Finnish children in our previous studies.

RESULTS

The distributions of the studied IL17RA wild versus variant genotypes and major versus minor allele frequencies did not differ between bronchiolitis cases and population controls. These variations showed no significant association with asthma or allergic rhinitis nor with lung function reduction at 5-7 or 11-13 years of ages. Only 5.6% to 6.4% of the variations were homozygous.

CONCLUSIONS

The IL17RA gene variations that were studied showed no association with susceptibility to severe bronchiolitis in infancy, nor with post-bronchiolitis asthma or lung function at school age. Future studies should evaluate other IL17RA polymorphisms and include more cases, and especially cases with homozygous variations.

IL17F rs763780 single nucleotide polymorphism is associated with asthma after bronchiolitis in infancy

AIM

Interleukin-17F (IL-17F) is involved with asthma. The aim of this study was to evaluate the association of IL17F polymorphisms with childhood asthma after bronchiolitis in infancy.

METHODS

We invited 166 children who were hospitalised for bronchiolitis at younger than 6 months of age to follow-up visits at 5-7 years and 11-13 years of ages. Asthma and allergy diagnoses, asthma-presumptive symptoms and use of inhaled corticosteroids (ICSs) were registered. Blood samples were available for IL17F rs763780 (T/C), rs11465553 (C/T) and rs7741835 (C/T) determinations in 165 cases.

RESULTS

The presence of IL17F rs11465553 and rs7741835 variations showed no significant associations with any asthma or allergy outcome at either 5-7 years or 11-13 years of ages. Instead, children with the variant IL17F rs763780 genotype had used more often ICSs between the follow-up visits from 5-7 to 11-13 years (adjusted OR 3.58) than those with the wild genotype. Children with the variant IL17F rs763780 genotype reported more often doctor-diagnosed atopic dermatitis (adjusted OR 2.71) at 11-13 years of age than those with the wild genotype.

CONCLUSION

This prospective long-term follow-up study provided preliminary evidence on the association of the IL17F rs763780 polymorphism with asthma at school age after bronchiolitis in infancy.

Recurrent Wheezing and Asthma After Respiratory Syncytial Virus Bronchiolitis

Background: Respiratory syncytial virus (RSV) is the most common pathogen of acute bronchiolitis in children, which sometimes triggers the development of recurrent wheezing and increases the risk of childhood asthma. Methods: We enrolled 425 children who were diagnosed with RSV-infected bronchiolitis at the department of pulmonology, Children's Hospital Zhejiang University School of Medicine in 2011. Long-term follow-up was performed to explore the consequence of bronchiolitis on subsequent recurrent wheezing and asthma. Results: Of 425 patients, 266 cases completed the entire follow-up, the mean age of onset was 4.9 (3.3) months, and the male-to-female ratio was 2.5. The mean birth weight of all patients was 3.22 (0.63) kg, and the number of patients who had a history of cesarean section was 148. According to the outcome of follow-up, 36 were in the recurrent wheezing (RW) group, 65 were in the asthma (AS) group, and the remaining 165 were in the completely recovered (CR) group. The age of onset was older and the birth weights were higher in the AS group than those in the CR group (P < 0.05). And the higher proportion of cesarean sections was higher in the RW group than that in the CR group (P < 0.05). Furthermore, we found a remarkable increasing of serum IgE in the AS groups than that in the CR group (P < 0.01). Multiple logistic regression analysis showed that the cesarean section was the risk factor for the development of recurrent wheezing and the higher birth weight was the risk factor for the development of asthma. Conclusion: RSV bronchiolitis might increase the incidence of recurrent wheezing and asthma. Allergic constitution was an important prerequisite for the occurrence of asthma, and related risk factor such as cesarean section can only increase recurrent wheezing to a certain extent within a certain period of time. And we also find higher birth weight and older onset age for those who develop asthma, which should be verified in the future.

Advances and recent developments in asthma in 2020

In this review, we discuss recent publications on asthma and review the studies that have reported on the different aspects of the prevalence, risk factors and prevention, mechanisms, diagnosis, and treatment of asthma. Many risk and protective factors and molecular mechanisms are involved in the development of asthma. Emerging concepts and challenges in implementing the exposome paradigm and its application in allergic diseases and asthma are reviewed, including genetic and epigenetic factors, microbial dysbiosis, and environmental exposure, particularly to indoor and outdoor substances. The most relevant experimental studies further advancing the understanding of molecular and immune mechanisms with potential new targets for the development of therapeutics are discussed. A reliable diagnosis of asthma, disease endotyping, and monitoring its severity are of great importance in the management of asthma. Correct evaluation and management of asthma comorbidity/multimorbidity, including interaction with asthma phenotypes and its value for the precision medicine approach and validation of predictive biomarkers, are further detailed. Novel approaches and strategies in asthma treatment linked to mechanisms and endotypes of asthma, particularly biologicals, are critically appraised. Finally, due to the recent pandemics and its impact on patient management, we discuss the challenges, relationships, and molecular mechanisms between asthma, allergies, SARS-CoV-2, and COVID-19.

Respiratory syncytial virus prophylaxis for prevention of recurrent childhood wheeze and asthma: a systematic review

BACKGROUND

Acute bronchiolitis caused by respiratory syncytial virus (RSV) has been associated with greater risk of recurrent wheezing and asthma. However, it is unclear whether this association is causal. RSV-specific monoclonal antibodies have been shown to reduce RSV-related hospitalisations in high-risk infants, but the longer-term follow-up has given conflicting evidence for prevention of recurrent wheeze or asthma.

OBJECTIVE

We performed a systematic review and meta-analysis to determine whether monoclonal antibody prophylaxis against RSV bronchiolitis reduces the risk of subsequent recurrent wheeze or asthma. If so, this may support the hypothesis of causality.

METHODS

Studies were identified via an online database search using Embase, MEDLINE, PubMed, Web of Science and the Cochrane Library. Manufacturers of monoclonal antibodies were contacted directly for unpublished data. The intervention of interest was RSV monoclonal antibody prophylaxis, and the primary outcome measure was recurrent wheeze and/or asthma. Studies were screened according to inclusion/exclusion criteria. Included studies were evaluated for quality and assessed for bias independently by 3 reviewers using the 'Grading of Recommendations Assessment, Development and Evaluation' (GRADE) approach. Results were extracted into 2 × 2 outcome tables and a meta-analysis carried out producing forest plots based on relative risk. Heterogeneity was assessed using the I2 statistic.

RESULTS

The search identified 141 articles, which, after screening, resulted in eight studies (2 randomised controlled trials), thus including 11,195 infants in the meta-analysis. The overall result demonstrated a non-statistically significant reduction in relative risk of developing recurrent wheeze or asthma (RR 0.60; 95% CI 0.31 to 1.16). Study quality was generally low with evidence of publication bias and statistical heterogeneity. However, sub-group analysis excluding studies deemed to be 'very low' quality showed a relative risk of 0.42 (95% CI 0.22 to 0.80, p = 0.008). A further sub-group analysis for infants aged 32 to < 36 weeks showed a statistically significant relative risk of 0.35 (95% CI 0.14 to 0.86, p = 0.02).

DISCUSSION

We did not identify an overall statistically significant benefit. However, our two sub-group analyses did find statistically significant benefits of monoclonal antibody therapy on the risk of recurrent wheeze and asthma. The main limitation of this study is the lack of high-quality randomised controlled trials, highlighting the need for more research in this field.

IL33 rs1342326 gene variation is associated with allergic rhinitis at school age after infant bronchiolitis

AIM

Interleukin (IL)-33, encoded by the IL33 gene, is associated with allergy and asthma. We evaluated IL33 rs1342326 polymorphism in relation to asthma, asthma medication and allergic rhinitis after infant bronchiolitis.

METHODS

IL33 rs1342326 polymorphism was studied in children, who were hospitalised for bronchiolitis at age younger than 6 months and who were prospectively followed until 5-7 years (N = 141) and 11-13 years (N = 125) of ages.

RESULTS

The presence of the wild AA vs variant AC or CC genotypes of the IL33 rs1342326 showed no significant associations with previous or current asthma at the mean ages of 6.4 or 11.7 years. However, 22.5% of children with the variant genotype used inhaled corticosteroids at the 5-7 years of visit (adjusted OR: 2.94, 95% CI: 1.04-8.33 vs those 8.9% with the wild genotype). The variant IL33 rs1342326 genotype was associated with allergic rhinitis at 6.4 years (adjusted OR: 2.17, 95% CI: 1.01-4.76) and 11.7 years (3.23, 1.18-9.09) of ages.

CONCLUSION

The frequent use of asthma control medication in 6.4-year-old children with IL33 rs1342326 polymorphism suggests that this variation may increase susceptibility to severe asthma at preschool age. The IL33 rs1342326 variant genotype was associated with a 3-fold risk of allergic rhinitis at school age.

The need for clean air: The way air pollution and climate change affect allergic rhinitis and asthma

Air pollution and climate change have a significant impact on human health and well-being and contribute to the onset and aggravation of allergic rhinitis and asthma among other chronic respiratory diseases. In Westernized countries, households have experienced a process of increasing insulation and individuals tend to spend most of their time indoors. These sequelae implicate a high exposure to indoor allergens (house dust mites, pets, molds, etc), tobacco smoke, and other pollutants, which have an impact on respiratory health. Outdoor air pollution derived from traffic and other human activities not only has a direct negative effect on human health but also enhances the allergenicity of some plants and contributes to global warming. Climate change modifies the availability and distribution of plant- and fungal-derived allergens and increases the frequency of extreme climate events. This review summarizes the effects of indoor air pollution, outdoor air pollution, and subsequent climate change on asthma and allergic rhinitis in children and adults and addresses the policy adjustments and lifestyle changes required to mitigate their deleterious effects.

Toll-like receptor 10 rs4129009 gene polymorphism is associated with post-bronchiolitis lung function in adolescence

AIM

The aim was to evaluate the association of polymorphisms in the Toll-like receptor (TLR) 2 subfamily encoding genes with lung function by spirometry at 10-13 years of age in children who had been hospitalised for bronchiolitis at <6 months of age.

METHODS

In a prospective cohort of 166 former bronchiolitis patients, 138 returned a structured questionnaire and 89 attended a clinical follow-up visit including spirometry before and after bronchodilation at 10-13 years of age. Data on polymorphisms of the TLR1, TLR2, TLR6 and TLR10 genes were available from 81-82 children.

RESULTS

In the TLR10 rs4129009, the wild (AA) genotype was associated with lower FEV1/FVC before (92.4 vs 97.4, P = .002) and after (95.5 vs 98.6, P = .011) bronchodilator administration, compared to those with the variant genotype. When the TLR10 rs4129009 and TLR2 rs5743708 genotypes, and the TLR10 rs4129009 and TLR1 rs5743618 genotypes, respectively, were analysed as combined, both baseline and post-bronchodilator FEV1/FVC were lowest in the subjects with the wild (AA) genotype of the TLR10 rs4129009.

CONCLUSION

In this post-bronchiolitis follow-up, lung function in children with the variant TLR10 rs4129009 genotype with potentially altered TLR10 function was superior to lung function in those with the wild genotype.

Respiratory syncytial virus prophylaxis for prevention of recurrent childhood wheeze and asthma: a protocol for a systematic review

BACKGROUND

Lower respiratory tract infection (LRTI) caused by respiratory syncytial virus (RSV) has been associated with greater risk of recurrent wheezing and subsequent asthma. However, it is still unclear whether this association is causal or not. RSV-specific monoclonal antibodies have been shown to reduce RSV-related hospitalisations in high-risk infants, i.e. those born pre-term, but the longer term follow-up has given conflicting evidence for the prevention of recurrent wheeze or asthma.

OBJECTIVE

We aim to perform a systematic review and meta-analysis to determine whether or not prophylaxis with a monoclonal antibody for prevention of RSV-bronchiolitis reduces the risk of subsequent recurrent wheeze or asthma. If so, this would support the hypothesis that the association between RSV and recurrent wheeze and/or asthma is causative.

METHODS

To identify relevant studies, we will search a number of databases including Medline, Embase, PubMed and Web of Science and will also manually look for unpublished data by contacting the manufacturers of monoclonal antibodies. The intervention being investigated is RSV-specific monoclonal antibody prophylaxis, and the outcome being measured is recurrent wheeze and/or asthma. Studies will be screened according to inclusion/exclusion criteria, to include primary studies of any study design type. Eligible studies will then be evaluated for quality and assessed for bias independently by three reviewers using the 'Grading of Recommendations Assessment, Development and Evaluation' (GRADE) approach. The results of the studies will be extracted into 2 × 2 outcome tables, and a meta-analysis will be carried out to produce forest plots based on relative risk. Heterogeneity will be assessed using the I 2 statistic. The statistical software we will use is StatsDirect.

DISCUSSION

This review will aid in determining if the relationship between RSV and asthma development is a causal one, by showing the effect (if any) of RSV prophylaxis on subsequent recurrent wheeze/asthma. If this study shows RSV prophylaxis to have no effect on the outcome of recurrent wheeze/asthma, the question of causality remains.

Interleukin-10 gene polymorphism rs1800896 is associated with post-bronchiolitis asthma at 11-13 years of age

AIM

Interleukin-10 (IL-10) is an anti-inflammatory cytokine that is involved with bronchiolitis and asthma. We evaluated associations between four IL-10 polymorphisms, namely rs1800871, rs1800872, rs1800890 and rs1800896, and post-bronchiolitis asthma in young adolescents.

METHODS

The cohort consisted of 125 children hospitalised for bronchiolitis at Tampere University Hospital, Finland, in 2000-2004, at less than six months of age. At 11-13 years, asthma diagnoses and asthma-presumptive symptoms, allergic rhinitis and use of inhaled corticosteroids (ICS) were registered. Data on the four polymorphisms and their genotypes, haplotypes and allele frequencies were analysed in relation to asthma, allergic rhinitis and asthma medication.

RESULTS

The variant IL-10 rs1800896 genotype was associated with less persistent asthma at five to seven and 11-13 years of age (4.3 versus 15.2%, p = 0.04) than the wild genotype and less ICS use during the previous 12 months (5.4 versus 18.2%, p = 0.03), as was the variant allele G. Allele A was associated with more persistent asthma and ICS use. The significant differences between the variant and wild genotypes were lost in adjusted logistic regression, but the direction of the association remained.

CONCLUSION

IL-10 rs1800896 gene polymorphism was associated with post-bronchiolitis asthma at 11-13 years of age in children hospitalised for bronchiolitis at less than six months of age.

History of allergic rhinitis and risk of asthma; a systematic review and meta-analysis

Background

Allergic rhinitis has been suspected to be a risk factor for asthma in several studies but this association is not firmly established. The objective of this study was to synthesize the evidence of the association between allergic rhinitis and the risk of asthma through a systematic review and meta-analysis.

Methods

We performed a search in Medline, Scopus, ISI Proceedings databases and other databases from inception until February 2019, followed by manual search to identify potentially relevant case-control and cohort studies that reported relative risk estimates and confidence intervals of the association between allergic rhinitis and asthma. Cross-sectional studies were excluded. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using fixed and random effects models and quality of studies was assessed through a modified version of the Newcastle-Ottawa scale.

Results

Twenty-nine eligible studies, 22 cohort and 7 case-control studies, with a total of 274489 subjects, were included in the meta-analysis. The results show that history of allergic rhinitis is significantly associated with the occurrence of asthma (OR = 3.82; 95% CI: 2.92–4.99). European studies showed a stronger association (OR = 4.35; (95% CI: 3.12–6.06) than non-European studies (OR = 2.75; 95% CI: 2.16–3.50), and case-control studies showed a stronger association (OR = 4.71; 95% CI: 3.58–6.17) than cohort studies (OR = 3.42; 95% CI: 2.60–4.50).

Conclusions

This meta-analysis shows that allergic rhinitis is strongly associated with asthma. Further prospective studies on the effect of treatment of allergic rhinitis on the development of asthma are needed. Relief of airway allergic manifestations may need dual control of allergic rhinitis and asthma.

Registration

PROSPERO database with registration number CRD42017055156.

Toll-like receptor 1 and 10 variations increase asthma risk and review highlights further research directions

AIM

This paper summarises variations in the genes encoding toll-like receptors (TLRs) in relation to the aetiology and outcome of infant bronchiolitis. It compares the literature with research carried out by our group.

METHODS

A mini review was conducted to provide context for a study carried out at the Department of Paediatrics, Tampere University Hospital, Finland. In 2000-2004, 187 infants were hospitalised for bronchiolitis and then followed up: 129 at 1.5 years of age, 166 at 5-7 years of age and 138 at 11-13 years of age.

RESULTS

The review showed that the Finnish bronchiolitis study was the only prospective study on the association between TLRs and the emergence of childhood asthma or lung function reduction after bronchiolitis in infancy. It found that TLR1 and TLR10 variant genotypes were associated with more asthma at 5-7 and 11-13 years, with inconsistent results for the other eight TLR genes. Large population-based studies were also identified that stressed the importance of the TLR2 subfamily members in childhood asthma.

CONCLUSION

Our study found that variations in the TLR1 and TLR10 genes increased the asthma risk after bronchiolitis. The mini review calls for further research on the TLR2 subfamily in bronchiolitis and childhood asthma.

Prospective study confirms that bronchiolitis in early infancy increases the risk of reduced lung function at 10-13 years of age

AIM

This study evaluated children hospitalised for bronchiolitis at less than six months of age to see if they had reduced lung function in early adolescence.

METHODS

We have prospectively followed 166 children hospitalised for infant bronchiolitis in 2001-2004 at Tampere University Hospital, Finland. At 10-13 years of age, flow-volume spirometry was measured in 89 cases and 108 controls without infant bronchiolitis from the local population register. Parameters of flow-volume spirometry before and after bronchodilation were analysed.

RESULTS

Forced expiratory volume in one second/forced vital capacity (FEV1/FVC) after bronchodilation was lower in cases than controls. FEV1 was pathological - under the 5th percentile of the national references - in 25% of cases and 12% of controls (p = 0.020) before bronchodilation and in 18% of cases and 5% of controls (p = 0.003) after bronchodilation. FEV1/FVC was pathological in 25% of cases and 13% of controls (p = 0.034) before bronchodilation. Logistic regression, adjusted for current asthma and maternal smoking, showed that infant bronchiolitis was associated with pathological FEV1 before (odds ratio 2.4) and after (odds ratio 4.4) bronchodilation. The result was similar for positive respiratory syncytial virus cases.

CONCLUSION

Reduced FEV1 after bronchodilation was found in early adolescence after infant bronchiolitis, suggesting irreversible bronchial obstruction.