Adult asthma after non-respiratory syncytial virus bronchiolitis in infancy: subgroup analysis of the 20-year prospective follow-up study

The role of respiratory syncytial virus- and rhinovirus-induced bronchiolitis in recurrent wheeze and asthma-A systematic review and meta-analysis

INTRODUCTION

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis. RSV-induced bronchiolitis has been associated with preschool wheeze and asthma in cohort studies where the comparison groups consist of healthy infants. However, recent studies identify rhinovirus (RV)-induced bronchiolitis as a potentially stronger risk factor for recurrent wheeze and asthma.

AIM

This systematic review and meta-analysis aimed to compare the associations of RSV- and RV-induced bronchiolitis with the development of preschool wheeze and childhood asthma.

METHODS

We performed a systematic search of the published literature in five databases by using a MeSH term-based algorithm. Cohort studies that enrolled infants with bronchiolitis were included. The primary outcomes were recurrent wheeze and asthma diagnosis. Wald risk ratios and odds ratios (ORs) were estimated, along with their 95% confidence intervals (CIs). Individual and summary ORs were visualized with forest plots.

RESULTS

There were 38 studies included in the meta-analysis. Meta-analysis of eight studies that had data on the association between infant bronchiolitis and recurrent wheeze showed that the RV-bronchiolitis group were more likely to develop recurrent wheeze than the RSV-bronchiolitis group (OR 4.11; 95% CI 2.24-7.56). Similarly, meta-analysis of the nine studies that had data on asthma development showed that the RV-bronchiolitis group were more likely to develop asthma (OR 2.72; 95% CI 1.48-4.99).

CONCLUSION

This is the first meta-analysis that directly compares between-virus differences in the magnitude of virus-recurrent wheeze and virus-childhood asthma outcomes. RV-induced bronchiolitis was more strongly associated with the risk of developing wheeze and childhood asthma.

Asthma, atopy and lung function in young adults after hospitalisation for bronchiolitis in infancy: impact of virus and sex

Background

Hospitalisation for bronchiolitis is a risk factor for asthma and impaired lung function during childhood, but outcomes in young adults are poorly described. Our primary aim was to study the prevalence of asthma and atopy, and lung function at 17–20 years of age after bronchiolitis in infancy and, secondarily, the impact of viral aetiology (respiratory syncytial virus (RSV) vs non-RSV) and sex on these outcomes.

Methods

This Norwegian cohort study enrolled 225 young adults hospitalised for bronchiolitis in infancy during 1996–2001 and 167 matched control subjects. The follow-up included questionnaires for asthma and examinations of lung function and atopy. Outcomes were analysed by mixed effects regressions.

Results

Current asthma was more frequent in the postbronchiolitis group versus the control group: 25.1% (95% CI 19.0% to 31.2%) vs 13.1% (95% CI 7.9% to 18.2%), but not atopy: 44.3% (95% CI 37.1% to 51.5%) vs 48.2% (95% CI 40.5% to 55.8%), adjusted predicted proportions (95% CIs). Asthma prevalence did not differ between the RSV group and the non-RSV group: 24.0% (95% CI 16.1% to 32.0%) vs 23.8% (95% CI 12.8% to 34.7%) nor between sexes. Forced expiratory volume in 1 s (FEV₁), the ratio FEV₁/forced vital capacity (FVC), and forced expiratory flow between 25% and 75% of FVC, were lower in the postbronchiolitis group.

Conclusion

Young adults hospitalised for bronchiolitis had higher prevalence of asthma, but not atopy, and a more obstructive lung function pattern than control subjects. The asthma prevalence was high after both RSV bronchiolitis and non-RSV bronchiolitis, and there was no difference between sexes. Bronchiolitis in infancy is associated with respiratory morbidity persisting into young adulthood.

Pulmonary function sequelae after respiratory syncytial virus lower respiratory tract infection in children: A systematic review

Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) during early childhood may be associated with subsequent pulmonary sequelae, including recurrent wheezing and asthma. We undertook a systematic review to investigate the pulmonary function sequelae following RSV LRTI in the first 3 years of life. The systematic review protocol was registered on PROSPERO (CRD42018087168). PubMed, Scopus, Cochrane Library, and World Health Organization Global Index Medicus, as well as ClinicalTrials.gov and Cochrane Central Register of Controlled Trials, were searched up until 15 June 2019 for published and unpublished interventional and observational studies with the end-point outcome of pulmonary function testing (PFT) after a proven RSV LRTI in the first 3 years of life. Two independent reviewers screened all the titles, abstracts and full texts. Data were extracted using a standardized data extraction form. Corresponding authors were contacted for additional information if required. All studies were assessed for risk of bias using the Newcastle-Ottawa quality assessment scale. The final analysis included 31 studies. Thirteen studies using spirometry reported no association between RSV LRTI and pulmonary function sequelae. The remaining 16 reported abnormal spirometry; 12 obstructive airways disease, three restrictive lung disease, and one mixed lung disease. The heterogeneity in PFT techniques, different ages at testing, and methods used for reporting outcomes made direct comparisons or pooled effect estimates impossible. Children with confirmed RSV LRTI during the first 3 years of life often have abnormal PFTs, favoring obstructive airways disease. The evidence, however, is not overwhelming with conflicting results between studies.

Does respiratory syncytial virus lower respiratory illness in early life cause recurrent wheeze of early childhood and asthma? Critical review of the evidence and guidance for future studies from a World Health Organization-sponsored meeting

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection (LRTI) and hospitalization in infants and children globally. Many observational studies have found an association between RSV LRTI in early life and subsequent respiratory morbidity, including recurrent wheeze of early childhood (RWEC) and asthma. Conversely, two randomized placebo-controlled trials of efficacious anti-RSV monoclonal antibodies (mAbs) in heterogenous infant populations found no difference in physician-diagnosed RWEC or asthma by treatment group. If a causal association exists and RSV vaccines and mAbs can prevent a substantial fraction of RWEC/asthma, the full public health value of these interventions would markedly increase. The primary alternative interpretation of the observational data is that RSV LRTI in early life is a marker of an underlying predisposition for the development of RWEC and asthma. If this is the case, RSV vaccines and mAbs would not necessarily be expected to impact these outcomes. To evaluate whether the available evidence supports a causal association between RSV LRTI and RWEC/asthma and to provide guidance for future studies, the World Health Organization convened a meeting of subject matter experts on February 12-13, 2019 in Geneva, Switzerland. After discussing relevant background information and reviewing the current epidemiologic evidence, the group determined that: (i) the evidence is inconclusive in establishing a causal association between RSV LRTI and RWEC/asthma, (ii) the evidence does not establish that RSV mAbs (and, by extension, future vaccines) will have a substantial effect on these outcomes and (iii) regardless of the association with long-term childhood respiratory morbidity, severe acute RSV disease in young children poses a substantial public health burden and should continue to be the primary consideration for policy-setting bodies deliberating on RSV vaccine and mAb recommendations. Nonetheless, the group recognized the public health importance of resolving this question and suggested good practice guidelines for future studies.

Bronchiolitis in young infants: is it a risk factor for recurrent wheezing in childhood?

BACKGROUND

Acute bronchiolitis in infancy is considered a risk factor for recurrent wheezing episodes in childhood. The present study assessed prevalence, clinical manifestations and risk factors for recurrent wheezing events during the first 3 years of life and persistent wheezing events beyond this age in children hospitalized as young infants with acute bronchiolitis.

METHODS

Two groups of children aged 6 years were included. The study group comprised 150 children with a history of hospitalization for bronchiolitis, with the first event at <6 months of age. The control group comprised 66 age- and sex-matched children with no history of bronchiolitis before 6 months of age. Children in both groups had been followed until 6 years of age by their pediatricians; data were obtained retrospectively by reviewing ambulatory records during children's visits in pediatricians' clinics. The data included epidemiological parameters, prevalence, age at onset, number of and treatments given for episodes of wheezing events prior to 6 years of age, pathogens detected, and severity of acute bronchiolitis in the study group.

RESULTS

Overall, 58% and 27% of children in the study and control groups, respectively (P=0.001) had recurrent wheezing episodes prior to the age of 3 years. Children in the study group had earlier onset of recurrent wheezing, had more episodes of wheezing, and required more bronchodilator and systemic steroids treatments compared to the control group.

CONCLUSION

Hospitalization within the first six months of life for acute bronchiolitis is an independent risk factor for recurrent wheezing episodes during the first 3 years of life.

Low eosinophils during bronchiolitis in infancy are associated with lower risk of adulthood asthma

BACKGROUND

Infant bronchiolitis may be the first manifestation of asthma.

AIM

To evaluate the association of early-childhood risk or protective factors for asthma and lung function reduction in adults 30 years after bronchiolitis in infancy.

METHODS

Forty-seven former bronchiolitis patients attended the clinical study at the median age of 29.5 years, including doctoral examination and measurement of post-bronchodilator lung function with flow-volume spirometry. Data on early-life risk factors including blood eosinophil counts on admission for bronchiolitis and on convalescence 4-6 weeks after bronchiolitis were available.

RESULTS

Low blood eosinophil count <0.25 × 10E9/l on admission for bronchiolitis was a significant protective factor and high blood eosinophil count >0.45 × 10E9/l on convalescence was a significant risk factor for asthma in adulthood independently from atopic status in infancy. Parental asthma and high blood eosinophil count >0.45 × 10E9/l during bronchiolitis were significant risk factors for irreversible airway obstruction (FEV1/FVC ratio below the 5th percentile lower limit of normality after bronchodilation).

CONCLUSION

Our adjusted analyses confirmed that eosinopenia during infant bronchiolitis predicted low asthma risk and eosinophilia outside infection predicted high asthma risk up to the age of 28-31 years. Parental asthma and eosinophilia during bronchiolitis were recognized as risk factors for irreversible airway obstruction.

Recurrent wheezing 36 months after bronchiolitis is associated with rhinovirus infections and blood eosinophilia

AIM

Links between respiratory syncytial virus bronchiolitis and asthma are well known, but few studies have dealt with wheezing following bronchiolitis induced by other viruses. We assessed the risk factors for recurrent wheezing in infants hospitalised for acute viral bronchiolitis.

METHODS

We followed 313 infants for three years after they were hospitalised for bronchiolitis, caused by 14 different viruses, to identify risk factors for recurrent wheezing. Parents provided feedback on wheezing episodes during telephone interviews 12 (n = 266), 24 (n = 242) and 36 (n = 230) months after hospitalisation.

RESULTS

The frequency of wheezing episodes diminished during the follow-up period: 137 children (51.7%) at 12 months, 117 (48.3%) at 24 months and 93 (40.4%) at 36 months. The risk of wheeze after three years was OR = 7.2 (95% CI 3.9-13.3) if they had episodes of wheezing during the first year after bronchiolitis, 16.8 (8.7-32.7) if they had episodes of wheezing during the second year and 55.0 (22.7-133.2) if they wheezed during both years. Blood eosinophils >400 cells/μL (OR 7.7; CI 1.4-41.8) and rhinovirus infections (3.1; 1.0-9.4) were the major risk factors for recurrent wheezing.

CONCLUSION

Recurrent wheezing 36 months after infant bronchiolitis was associated with rhinoviruses and blood eosinophilia.

Viral bronchiolitis in children: a common condition with few therapeutic options

Even though bronchiolitis is a disease that has been recognized for many years, there are still few therapeutic strategies beyond supportive therapies. Bronchiolitis is the most frequent cause of hospital admission in children less than 1 year of age. The incidence is estimated to be about 150° million cases a year worldwide, and 2-3% of these cases require hospitalization. It is acknowledged that viruses cause bronchiolitis, but most of the studies focus on RSV. The RSV causes a more severe form of bronchiolitis in children with risk factors including prematurity, cardiovascular disease and immunodeficiency. Other viruses involved in causing bronchiolitis include RV, hMPV, hBoV and co-infections. The RV seems to be associated with a less severe acute disease, but there is a correlation between the early infection and subsequent wheezing bronchitis and asthma in later childhood and adulthood. The supportive therapies used are intravenous fluids and oxygen supplement administered by nasal cannula or CPAP in most complicated patients. Additional pharmacological therapies include epinephrine, 3% hypertonic saline and corticosteroids. The Epinephrine seems to have the greatest short-term benefits and reduces the need of hospital admission, whereas hypertonic saline and corticosteroids seem to reduce the length of hospital stay. As bronchiolitis is such a prevalent disease in children and RV seems to play an important role, perhaps more studies should center around the RV's contribution to the initial disease and following pathology.

Adolescent asthma after rhinovirus and respiratory syncytial virus bronchiolitis

BACKGROUND AND AIMS

Asthma risk is increased after bronchiolitis in infancy. Recent studies have suggested that the risk may be dependent on the causative virus. The aim of the study was to evaluate the asthma risk in adolescence in subjects hospitalized for rhinovirus or respiratory syncytial virus (RSV) bronchiolitis in infancy.

SUBJECTS AND METHODS

At the median age of 16.5 years, a questionnaire was sent to 96 study subjects hospitalized for bronchiolitis at <24 months of age and since then prospectively followed-up. Sixty-seven (70%) returned the fulfilled questionnaire. RSV and rhinovirus etiology of bronchiolitis had been studied in serum and respiratory samples obtained on admission in infancy. The occurrence of asthma was compared between former bronchiolitis patients and population controls recruited for this study in adolescence.

RESULTS

Doctor-diagnosed asthma was present in 30% of former bronchiolitis patients and in 5% of controls (OR 7.9, 95% CI 3.3-19.3). The respective figures for self-reported asthma were 64% and 11% (OR 14.7, 95% CI 7.2-30.0). Self-reported asthma was more common in the former rhinovirus than RSV patients (83.3% vs. 47.6%, P = 0.023, mixed infections included; 81.3% vs. 50%, P = 0.067, mixed infections excluded).

CONCLUSIONS

Patients hospitalized for RSV and rhinovirus bronchiolitis at <24 months of age had an increased asthma risk at 15-18 years of age compared with population controls. Within the former bronchiolitis group, the risk of self-reported asthma was higher after non-RSV versus RSV and after rhinovirus versus non-rhinovirus bronchiolitis.

Elevated risk of asthma after hospitalization for respiratory syncytial virus infection in infancy

Severe respiratory syncytial virus (RSV) infection in infancy is associated with substantial morbidity worldwide; whether it is a risk factor for childhood asthma is contentious. A systematic review of 28 articles was conducted, summarizing estimates of asthma risk after RSV hospitalization during infancy. Prevalence estimates of asthma, among those hospitalized for RSV in infancy, were from 8% to 63%, 10% to 92%, and 37%, at ages <5, 5 to 11, and ≥ 12 years, respectively. These rates were higher than those among non-hospitalized comparisons. The attributable risk of asthma due to RSV ranged from 13% to 22% and from 11% to 27% among children aged ≤ 5 and aged 5 to 11, respectively, and was 32% among children ≥ 12 years of age. Overall, 59% of asthma prevalence estimates from those previously hospitalized for RSV exceeded 20%, compared to only 6% of non-hospitalized comparison estimates. Despite variability in asthma prevalence estimates after RSV-related hospitalization, available data suggest a link between severe RSV infection in infancy and childhood asthma.

[Aetiology of bronchiolitis in hospitalised children in South-East Spain]

Introducción

La bronquiolitis es una de las infecciones respiratorias más comunes en niños menores de 2 años y una de las principales causas de ingreso en niños pequeños, especialmente durante el invierno.

Objetivos

Determinar la prevalencia y etiología de bronquiolitis en el sureste de España.

Material y métodos

Se realizó un estudio prospectivo durante la temporada de bronquiolitis (diciembre-abril). En el estudio se incluyeron niños menores de 18 meses ingresados en el hospital con motivo del primer episodio de bronquiolitis. Se analizaron aspirados nasofaríngeos mediante una técnica de reacción en cadena de la polimerasa (múltiple), precedida de transcripción inversa del ARN viral (RT-PCR).

Resultados

Se incluyeron en el estudio 235 niños, de cada uno de los cuales se obtuvo una muestra de aspirado nasofaríngeo. Se detectaron virus respiratorios en muestras de 204 niños (en total 287 virus). El virus respiratorio sincitial se detectó con mayor frecuencia seguido del rinovirus. Se observaron infecciones virales mixtas en el 36% de los niños en los que se detectó algún virus respiratorio. La asociación más frecuente fue el virus respiratorio sincitial A con rinovirus.

Conclusiones

Se detectaron virus respiratorios en la mayoría de los niños menores de 18 meses hospitalizados por bronquiolitis, en forma de infección mixta en el 36% de aquellos con infección viral.

Rhinovirus-induced bronchiolitis and asthma development

Human rhinovirus (HRV) and respiratory syncytial virus (RSV) are commonly associated with bronchiolitis. The breaking point in the dominance is approximately 12 months--rhinovirus dominates in the older children. Predisposition may markedly increase the prevalence of HRV bronchiolitis. Especially, low interferon responses and atopy-related factors have been associated with HRV bronchiolitis. The former has been considered as a sign of poor antiviral defense, and the latter could be associated with atopic airway inflammation in wheezing children. Although recurrent wheezing is common after both RSV and HRV bronchiolitis, HRV bronchiolitis carries a markedly higher risk of persistent wheezing until 6 years of age and for childhood asthma. This association has been independent from atopy at 7.2 (median) years of age. The increased risk of asthma in adulthood after non-RSV bronchiolitis vs. RSV bronchiolitis in infancy (at the time when PCR was not available for HRV diagnosis) offers indirect evidence for the association between HRV bronchiolitis and chronic asthma.

Diagnosis of allergy and asthma in childhood

Childhood asthma is a widespread health problem because of its epidemic prevalence, as asthma affects more than 300 million people worldwide. Results from cross-sectional and cohort studies show that asthma starts in childhood in a large proportion of cases. A proper diagnosis is easier to make in adults and school-age children, as permanent changes in lung development, the strong impact of environmental factors on the airways, the immunologic maturity process, and the use of some diagnostic tools make asthma more difficult to diagnose in preschool children. This period of a child's life is an interesting challenge for pediatricians and specialists. The aim of the present review is to analyze the current knowledge regarding making an early and accurate asthma diagnosis and therefore deciding on the correct treatment to gain control over asthma symptoms and minimize health risks.

Epidemiology of respiratory syncytial virus in children ≤2 years of age hospitalized with lower respiratory tract infections in the Russian Federation: a prospective, multicenter study

BACKGROUND

Respiratory syncytial virus (RSV) is the leading cause of severe lower respiratory tract infections among infants and young children, and is responsible for an estimated four million deaths per year globally. A monthly injection of palivizumab has been used for prophylaxis of serious RSV infections among high-risk children in 71 countries since 1998 and approval for use in the Russian Federation was obtained in February 2010. A recommendation for RSV prophylaxis in the Russian Federation would require knowledge of the prevalence and seasonality of RSV in that country.

METHODS

In a prospective, multicenter, epidemiological study of the prevalence, seasonality, and peak occurrence of RSV infection, children aged ≤2 years hospitalized for lower respiratory tract infections in three regions of the Russian Federation, from September 2008 through April 2009, were screened and tested for RSV using rapid immunochromatography of nasopharyngeal lavage. For subjects who were tested positive, hospitalization data were collected.

RESULTS

Of 519 children aged ≤2 years enrolled from September 11, 2008 through April 26, 2009, 197 tested positive for RSV (38.0%, 95% CI: 33.8, 42.3). The onset of the 2008-2009 RSV season in the Russian Federation occurred in late October 2008, similar to what is observed in other northern temperate zones. Peak activity occurred in early April 2009, when 62% of children enrolled tested positive for RSV.

CONCLUSION

The prevalence of serious RSV infections in the Russian Federation is similar to the prevalence previously identified in other temperate zones of the northern hemisphere. The seasonality of disease shifted towards early spring, with peak activity later in the season, within a range reported in other countries. These data provide further evidence of serious RSV infection in children in the Russian Federation, as well as guidance for timing of seasonal RSV prophylaxis, especially among individuals at high risk for serious RSV infection.

Respiratory syncytial virus infections in the adult asthmatic--mechanisms of host susceptibility and viral subversion

Respiratory syncytial virus (RSV), a single-stranded RNA virus of the Paramyxoviridae family, is a major cause of bronchiolitis in infants and is also conjectured to be an early-life influence on the development of asthma. Although the data supporting a role for RSV in bronchiolitis in children are robust and evidence to support its role in juvenile asthmatics exists, RSV's role in asthma pathogenesis in adults is not as clearly defined. The authors review the literature to further elucidate RSV's impact on adult asthmatics, including its importance as a cause of asthma exacerbations. They examine the morbidity associated with RSV infection and how the immune response may differ between adult asthmatics and nonasthmatics. They review the responses by specific cell types from adults with asthma that are stimulated by RSV. They also consider the role of early-life exposure to RSV and its contribution to asthma in adults. Lastly, they review the mechanisms by which RSV evades normal host immune responses and subverts these responses to its benefit.

Respiratory morbidity in adulthood after respiratory syncytial virus hospitalization in infancy

A prospective >25-year follow-up study evaluated the outcome of patients hospitalized for respiratory syncytial virus (RSV) infection at <24 months of age. Questionnaires were sent to 51 study subjects and to population controls. Self-reported asthma was present in 30% of the former RSV patients, compared with 3.8% of controls. In adjusted analyses, RSV hospitalization was an independent risk factor of adulthood asthma.

[Consensus conference on acute bronchiolitis (VI): prognosis of acute bronchiolitis. Review of scientific evidence]

We present a review of the evidence on prognosis of acute bronchiolitis, risk factors for severe forms, symptom or severity scores and risk of post-bronchiolitis asthma. Documented risk factors of long stay or PICU admission in hospitalized patients are: bronchopulmonary dysplasia and/or chronic lung disease, prematurity, congenital heart disease and age less than 3 months. Other less well documented risk factors are: tobacco exposure, history of neonatal mechanical ventilation, breastfeeding for less than 4 months, viral co-infection and other chronic diseases. There are several markers of severity: toxic appearance, tachypnea, hypoxia, atelectasis or infiltrate on chest radiograph, increased breathing effort, signs of dehydration, tachycardia and fever. Although we have some predictive models of severity, none has shown sufficient predictive validity to recommend its use in clinical practice. While there are different symptom or severity scores, none has proven to be valid or accurate enough to recommend their preferable application in clinical practice. There seems to be a consistent and strong association between admission due to bronchiolitis and recurrent episodes of wheezing in the first five years of life. However it is unclear whether this association continues in subsequent years, as there are discordant data on the association between bronchiolitis and asthma.

Adulthood asthma after wheezing in infancy: a questionnaire study at 27 years of age

BACKGROUND

Wheezing in early childhood is a heterogeneous condition, the longterm prognosis varying from total recovery to chronic asthma. Though short-term outcome has been actively studied, there is lack of data on long-term outcome until adulthood. The aim of the study was to evaluate the prevalence and risk factors of asthma at 26-29 years of age after early-life wheezing.

METHODS

At the median age of 27.3 years (range 26.3-28.6), a questionnaire was sent to 78 study subjects hospitalized for wheezing at <24 months of age, and 59 (76%) answered. Asthma, allergy and weight status were compared with selected controls followed up from birth and with non-selected population controls recruited for this adulthood study.

RESULTS

Doctor-diagnosed asthma was present in 20% of the former bronchiolitis patients, compared with 5% in the two control groups (OR 2.1, 95% CI 0.3-17.9 vs selected controls; OR 5.2, 95% CI 1.7-15.8 vs nonselected controls). The respective figures for current self-reported asthma were 41% and 7-10% (OR 11.4, 95% CI 2.3-56.1 vs selected controls; OR 12.2, 95% CI 4.4-33.7 vs nonselected controls). Current allergic rhinitis and current smoking were significantly associated with asthma, but current overweight or obesity was not. In multivariate analyses, early-life wheezing was an independent risk factor of adulthood asthma.

CONCLUSION

An increased asthma risk in early-life wheezers continues, even after many symptom-free years at school age, at least until 27 years of age.

Recurrent wheezing after respiratory syncytial virus or non-respiratory syncytial virus bronchiolitis in infancy: a 3-year follow-up

BACKGROUND

Recent studies have suggested that rhinovirus-associated early wheezing is a greater risk factor for development of recurrent wheezing in children than is early wheezing associated with respiratory syncytial virus (RSV). We determined the development of recurrent wheezing in young children within 3 years after hospitalization for RSV or non-RSV bronchiolitis.

METHODS

We identified retrospectively all children <2 years of age who were admitted to Turku University Hospital because of bronchiolitis in the months of August-December during 1988-2001. The primary outcome was recurrent wheezing that required long-term asthma medication. Data on asthma medications of the individual children were derived from the Social Insurance Institution of Finland.

RESULTS

Within the first year after hospitalization, 36 of 217 (16.6%) children with non-RSV bronchiolitis developed recurrent wheezing, compared with five of 199 (2.5%) children with RSV bronchiolitis [relative risk (RR) 6.6; 95% confidence interval (CI) 2.6-16.5]. The rates of recurrent wheezing were significantly increased in the non-RSV group also within 2 years (RR 2.9; 95% CI 1.7-5.1) and 3 years (RR 3.4; 95% CI 2.0-5.7) after hospitalization. The increased risk of recurrent wheezing in children with non-RSV-associated bronchiolitis was observed both in boys and girls at all time points of the 3-year follow-up, and it was not explained by the age difference between the RSV and non-RSV groups or any confounding seasonal factors.

CONCLUSION

Children hospitalized with bronchiolitis caused by other viruses than RSV develop recurrent wheezing at substantially higher rates during a 3-year follow-up period than do children with RSV-induced bronchiolitis.

Long-term outcomes of early childhood wheezing

PURPOSE OF REVIEW

To summarize the currently available data on the long-term outcome until young adulthood after early childhood wheezing. Asthma and lung function abnormalities were evaluated, with special attention to early-life risk factors.

RECENT FINDINGS

In postbronchiolitis studies, 30-40% of the patients hospitalized for wheezing at less than 24 months of age have had asthma at 17-20 years of age. In the Tucson birth cohort study, the respective figure after wheezing at less than 36 months of age was 30% at 22 years of age. Relapses after many nonsymptomatic years have been common. In postbronchiolitis studies, lung function has been reduced in 31-36%, concerning also postbronchodilator measurements. Thus, the changes in airways seem to be structural, being present from infancy until adulthood, as found in the Tucson study. Parental asthma, repeated early-life wheezing and early passive smoking have been the most important early-life predictors of both adulthood asthma and lung function abnormalities.

SUMMARY

Early childhood wheezing increases the risk for asthma and lung function abnormalities in young adulthood. Not only chronic childhood asthma continuing until adulthood but also asthma beginning in early adulthood seems to have its origin in early childhood.

Diagnosis, admission, discharge

The respiratory syncytial virus should be considered as the most likely pathogen in an infant or young child with a significant acute lower respiratory tract infection during the characteristic epidemic season. While the diagnosis of an RSV infection is relatively straight forward, the clinical diagnosis applied to the associate illness is far less clear cut. Criteria for assessment is based on clinical assessment of severity at examination and associated risk factors. Social factors may further influence the likelihood of admission. Guidelines are consistent in noting that there are no scoring systems or other tests that can reliably predict the need for supportive care or HDU admission. Criteria for the administration of oxygen vary. There are marked differences in the duration of hospitalisation for RSV admission between the USA, UK and Scandinavia. Longer length of admission is associated with significantly higher rates of nosicomial infection.

Innate immune response and bronchiolitis and preschool recurrent wheeze

Bronchiolitis and preschool recurrent wheeze (PSRW) are common paediatric problems causing significant morbidity and mortality in the first years of life. Respiratory syncytial virus (RSV) and rhinoviruses are the commonest pathogens associated with these illnesses. Why some infants are severely affected, requiring admission to hospital, whilst others experience a simple cold is not fully understood: research has suggested that the innate immune response to these viruses is important. The innate immune system has many components and activation or deficiency in one or many areas may explain the different clinical presentations and disease severities that can occur in these infants. This review will summarize the recent evidence highlighting how RSV and rhinoviruses may modulate the innate immune response in both bronchiolitis and PSRW, and discuss how these illnesses affect the long-term development of the infant lung and the possible susceptibility to persistent airway disease.

The impact of respiratory viral infection on wheezing illnesses and asthma exacerbations

The etiology and morbidity associated with asthma are thought to stem from both genetic factors and potentially modifiable environmental factors, such as viral infections. Although it is unclear whether respiratory viral infections cause asthma, observational studies have demonstrated a high rate of asthma in children with a history of severe viral lower respiratory tract infections during infancy, and viruses are associated with the majority of asthma exacerbations among both children and adults. This article discusses the pathogens associated with virus-induced wheezing illnesses during infancy and early childhood, the association of bronchiolitis during infancy with an increased risk of childhood asthma, and the association of respiratory viruses with asthma exacerbations in older children and adults.

Wheezing due to rhinovirus infection in infancy: Bronchial hyperresponsiveness at school age

BACKGROUND

Characteristics related to decreased lung function and increased bronchial responsiveness after early childhood wheezing requiring hospitalization are not fully established.

METHODS

Seventy-nine children with wheezing requiring hospitalization at age <2 years were prospectively followed up and re-investigated at age 5.6-8.8 years when the measurements of baseline lung function and bronchial responsiveness to exercise were performed.

RESULTS

At early school age, 23% of children had decreased lung function, and 13% had increased bronchial responsiveness to exercise. Predictors of decreased lung function were maternal history of smoking during pregnancy (odds ratio [OR], 12.8; 95% confidence interval [CI]: 1.2-139.6), parental history of asthma (OR, 4.3; 95%CI: 1.1-17.1), and female gender (OR, 4.0; 95%CI: 1.2-13.7). Increased bronchial responsiveness was associated with rhinovirus infection-induced wheezing in infancy (OR, 6.5; 95%CI: 1.2-36.3), and early cat or dog exposure leading to sensitization (OR, 26.6; 95%CI: 1.3-525.2). Inhaled anti-inflammatory therapy was common in children with rhinovirus infection-induced wheezing in infancy (n = 13/19; P = 0.001 vs children with other/no confirmed virus infection etiology for wheezing in infancy, n = 16/60), which may have improved lung function and attenuated bronchial responsiveness in them.

CONCLUSIONS

After early childhood wheezing requiring hospitalization, one-fourth of children will have decreased lung function and one-eighth of children will show increased bronchial responsiveness at school age. Gender, heredity of asthma, and antenatal exposure to tobacco smoke are predictors of decreased lung function, whereas rhinovirus infection etiology of wheeze and early animal exposure leading to sensitization are associated with increased bronchial responsiveness later in childhood.

Hypothesis--ultraviolet-B irradiance and vitamin D reduce the risk of viral infections and thus their sequelae, including autoimmune diseases and some cancers

Many viral infections reach clinical significance in winter, when it is cold, relative humidity is lowest and vitamin D production from solar ultraviolet-B irradiation is at its nadir. Several autoimmune diseases, such as multiple sclerosis, type 1 diabetes mellitus and asthma, are linked to viral infections. Vitamin D, through induction of cathelicidin, which effectively combats both bacterial and viral infections, may reduce the risk of several autoimmune diseases and cancers by reducing the development of viral infections. Some types of cancer are also linked to viral infections. The cancers with seemingly important risk from viral infections important in winter, based on correlations with increasing latitude in the United States, an index of wintertime solar ultraviolet-B dose and vitamin D, are bladder, prostate, testicular and thyroid cancer, Hodgkin's and non-Hodgkin's lymphoma, and, perhaps, gastric cancer. The evidence examined includes the role of viruses in the etiology of these diseases, the geographic and seasonal variation of these diseases, and the time of life when vitamin D is effective in reducing the risk of disease. In general, the evidence supports the hypothesis. However, further work is required to evaluate this hypothesis.