Does blood eosinophilia in wheezing infants predict later asthma? A prospective 18-20-year follow-up

Limited clinical role of blood eosinophil levels in early life atopic disease: A mother-child cohort study

BACKGROUND

Blood eosinophil count is a well-established biomarker of atopic diseases in older children and adults. However, its predictive role for atopic diseases in preschool children is not well established.

OBJECTIVE

To investigate the association between blood eosinophil count in children and development of atopic diseases up to age 6 years.

METHODS

We investigated blood eosinophil count at age 18 months and 6 years in relation to recurrent wheeze/asthma, atopic dermatitis, allergic rhinitis, and allergic sensitization during the first 6 years of life in the two Copenhagen Prospective Studies on Asthma in Childhood cohorts (n = 1111). Blood eosinophil count was investigated in association with remission of existing atopic disease, current atopic disease, and later development of atopic disease.

RESULTS

Blood eosinophil count at 18 months was not associated with current wheezing/asthma or atopic dermatitis, while blood eosinophil count at age 6 years was associated with increased occurrence of current wheezing/asthma (OR = 1.1; 1.04-1.16, p = .0005), atopic dermatitis (OR = 1.06; 1.01-1.1, p = .02), and allergic rhinitis (OR = 1.11; 1.05-1.18, p = .0002). Blood eosinophil count at 18 months did not predict persistence or development of recurrent wheeze/asthma or atopic dermatitis at age 6 years.

CONCLUSION

Blood eosinophil count at 18 months was not associated with current wheezing/asthma or atopic dermatitis and did not predict persistence or development of disease. This implies a limited clinical role of blood eosinophil levels in early-life atopic disease and questions the clinical value of blood eosinophil counts measured in toddlers as a predictive biomarker for subsequent atopic disease in early childhood.

Are BMI and adipokines associated with asthma, atopy and lung function in young adults previously hospitalized for bronchiolitis?

BACKGROUND

Children hospitalized for bronchiolitis have increased risk of asthma and low lung function persisting into adulthood, but the underlying mechanisms are poorly understood. Body mass index (BMI) and adipokines are associated with respiratory morbidity. We aimed to investigate if associations between BMI and adipokines and the outcomes asthma, atopy, and lung function differed between young adults previously hospitalized for bronchiolitis and control subjects.

METHODS

This sub study of a historical cohort enrolled 185 young adults previously hospitalized for bronchiolitis and 146 matched control subjects. Exposures (BMI and the adipokines: adiponectin, leptin, resistin, and ghrelin) and outcomes (asthma, atopy, and lung function) were measured cross-sectionally at 17-20 years of age. Associations were tested in regression models, and differences between the post-bronchiolitis- and control group were tested by including interaction terms.

RESULTS

BMI was associated with asthma and lung function, but we did not find that the associations differed between the post-bronchiolitis- and control group. We also found some associations between adipokines and outcomes, but only associations between adiponectin and forced vital capacity (FVC) and between resistin and current asthma differed between the groups (p-value interaction term 0.027 and 0.040 respectively). Adiponectin tended to be positively associated with FVC in the post-bronchiolitis group, with an opposite tendency in the control group. Resistin was positively associated with current asthma only in the control group.

CONCLUSION

The increased prevalence of asthma and impaired lung function observed in young adults previously hospitalized for bronchiolitis do not seem to be related to growth and fat metabolism.

Blood eosinophils during bronchiolitis: Associations with atopy, asthma and lung function in young adults

AIM

To study if blood eosinophils during bronchiolitis were associated with atopy, asthma and lung function in young adults and if these associations differed between respiratory syncytial virus (RSV) bronchiolitis and non-RSV bronchiolitis.

METHODS

This historical cohort enrolled 225 subjects. Blood eosinophils were measured during bronchiolitis in infancy, and the subjects were invited to a follow-up at 17-20 years of age including questionnaires for asthma and examinations of lung function and atopy.

RESULTS

The level of eosinophils was positively associated with subsequent atopy in the unadjusted analysis, but not in the adjusted analysis, and not with asthma. There was a negative association between the level of eosinophils and forced vital capacity (FVC) (-0.11; -0.19, -0.02) and forced expiratory volume in first second (FEV₁ ) (-0.12; -0.21, -0.03) (regression coefficient; 95% confidence interval). The non-RSV group had higher levels of eosinophils during bronchiolitis, but there was no interaction between the level of eosinophils and RSV status for any outcome.

CONCLUSIONS

The level of eosinophils during bronchiolitis was negatively associated with lung function in young adult age, but we found no associations with atopy or asthma. These associations were not different after RSV bronchiolitis compared to non-RSV bronchiolitis.

Viral wheezing in early childhood as a risk factor for asthma in young adulthood: A prospective long-term cohort study

Background and Aims

There is an increased risk of asthma after viral wheezing episodes in early childhood, but unfortunately, prospective longitudinal data until adulthood are mostly lacking. The aim of this cohort study was to evaluate the risk of asthma in young adulthood after hospitalization for viral wheezing episodes in early childhood.

Methods

The original cohort comprised 100 individuals aged <24 months who were hospitalized for viral wheezing episodes in 1992-1993. After the index episode, data on a diagnosis of asthma 1 year later and at median ages of 4.0, 7.2, and 12.3 years were recorded in follow-up visits. Forty-nine individuals attended the latest follow-up visit at the age of 17-20 years. Current asthma was diagnosed based on symptoms at the time of the last follow-up, use of inhaled corticosteroids and peak expiratory flow monitoring.

Results

A total of 26 (53%) of the 49 cohort individuals had asthma at a mean age of 18.8 years. In multivariate analyses, a diagnosis of asthma 1 year after index hospitalization and at ages 4.0, 7.2, and 12.3 years were significant risk factors for current asthma (adjusted odds ratios [aORs] of 7.13, 8.86, 8.05, and 21.16, respectively). Atopic dermatitis in infancy (aOR: 4.20) and eosinophilia on admission (5.18) were also significant predictive factors for asthma.

Conclusion

Over half (26/49) of the participants who had been hospitalized for viral wheezing episodes in early childhood had asthma in young adulthood. An asthma diagnosis at any age during childhood, as well as eosinophilia in early childhood, were independent significant predictive factors for asthma.

Performance of Three Asthma Predictive Tools in a Cohort of Infants Hospitalized With Severe Bronchiolitis

Childhood asthma develops in 30–40% of children with severe bronchiolitis but accurate prediction remains challenging. In a severe bronchiolitis cohort, we applied the Asthma Predictive Index (API), the modified Asthma Predictive Index (mAPI), and the Pediatric Asthma Risk Score (PARS) to predict asthma at age 5 years. We applied the API, mAPI, and PARS to the 17-center cohort of infants hospitalized with severe bronchiolitis during 2011–2014 (35th Multicenter Airway Research Collaboration, MARC-35). We used data from the first 3 years of life including parent interviews, chart review, and specific IgE testing to predict asthma at age 5 years, defined as parent report of clinician-diagnosed asthma. Among 875/921 (95%) children with outcome data, parent-reported asthma was 294/875 (34%). In MARC-35, a positive index/score for stringent and loose API, mAPI, and PARS were 24, 68, 6, and 55%, respectively. The prediction tools' AUCs (95%CI) ranged from 0.57 (95%CI 0.54–0.59) to 0.68 (95%CI 0.65–0.71). The positive likelihood ratios were lower in MARC-35 compared to the published results from the original cohorts. In this high-risk population of infants hospitalized with severe bronchiolitis, API, mAPI, and PARS had sub-optimal performance (AUC &lt;0.8). Highly accurate (AUC &gt;0.8) asthma prediction tools are desired in infants hospitalized with severe bronchiolitis.

Blood eosinophils, specific immunoglobulin E, and bronchiolitis severity

BACKGROUND

Bronchiolitis is the leading cause of hospitalization for United States infants. Blood eosinophil and serum specific IgE (sIgE) levels are separately linked to clinical severity but few studies have examined these biomarkers together.

OBJECTIVE

Among infants hospitalized for bronchiolitis, we investigated the association between (1) blood eosinophilia and severity, (2) sIgE sensitization and severity, and (3) interaction between the two biomarkers on severity.

METHODS

We enrolled 1016 infants hospitalized for bronchiolitis between 2011 and 2014 across 17 U.S. hospitals into a prospective cohort study. Of those, 873 (86%) had eosinophils measured and all had sIgE levels from blood collected at hospitalization. We investigated higher bronchiolitis severity using intensive care therapy as the outcome (i.e., intensive care unit admission, intubation, and/or receipt of continuous positive pressure ventilation).

RESULTS

Among 873 infants in the analytic cohort, 18% had blood eosinophilia of ≥3%, and 20% were positive for sIgE. With regard to bronchiolitis severity, 15% received intensive care therapy. In unadjusted analyses, eosinophils ≥3% was not associated with intensive care therapy, while sIgE was associated with a significantly higher risk (odds ratio [OR]: 1.44, 95% confidence interval [CI]: 1.08-1.92; p = .01). In a multivariable model for intensive care therapy, eosinophilia remained unassociated with severity, and sIgE remained associated (OR: 1.60, 95% CI: 1.05-2.45; p = .03). Also, sIgE did not modify the association between eosinophil level and intensive care therapy (pinteraction  = .14).

CONCLUSION

Blood eosinophilia of ≥3% was not associated with bronchiolitis severity. By contrast, sIgE was independently associated with bronchiolitis severity and did not modify the association between eosinophil level and severity.

Biomarkers in inflammometry pediatric asthma: utility in daily clinical practice

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

Elevated blood eosinophils in early infancy are predictive of atopic dermatitis in children with risk for atopy

BACKGROUND

Accessible markers to predict the development of atopic diseases are highly desirable but yet matter of debate.

OBJECTIVE

We investigated the role of blood eosinophils at 4 weeks and 7 months of life and their association with developing atopic dermatitis (AD) in a birth cohort of children with atopic heredity.

METHODS

Infant blood samples for eosinophil counts were taken from 559 infants at 4 weeks and from 467 infants at 7 month of life with at least one atopic parent. Elevation of blood eosinophils was defined as ≥ 5% of total leukocytes and the asscociation for the occurrence of AD was assessed by entering 2 × 2 tables and the odds ratios were estimated followed by hypothesis testing against the alternate working hypothesis: odds ratio < > 1. Survival analysis was carried out estimating the Kaplan-Meier product limit estimator from the life-time table of AD score and time to AD manifestation stratified by the eosinophil binary score.

RESULTS

Elevated blood eosinophils observed at 4 weeks were significantly associated with the occurrence of AD in the whole cohort at the age of 7 months (p = 0.007), 1 year (p = 0.004), 2 years (p = 0.007) and 3 years (p = 0.006) of life. AD occurred app. 12 weeks earlier in infants with elevated blood eosinophils at 4 weeks of life. Blood eosinophil counts ≥5% at 7 months of life failed to show significance for AD; for eosinophils at 4.5% a significant association at 7 months (p = 0.005), and 1 year of life (p = 0.039), 2 years (p = 0.033) and 3 years (p = 0.034) was observed.

CONCLUSION

Elevated blood eosinophils at age 4 weeks have a predictive value for the onset of atopic dermatitis in infancy and early childhood in children with high risk for atopy. Early eosinophil counts may therefore be helpful for counseling parents to provide infant skincare but furthermore identify individuals for interventional trials aiming at allergy prevention.

Relationships among aeroallergen sensitization, peripheral blood eosinophils, and periostin in pediatric asthma development

BACKGROUND

Biomarkers, preferably noninvasive, that predict asthma inception in children are lacking.

OBJECTIVE

Little is known about biomarkers of type 2 inflammation in early life in relation to asthma inception. We evaluated aeroallergen sensitization, peripheral blood eosinophils, and serum periostin as potential biomarkers of asthma in children.

METHODS

Children enrolled in the Childhood Origins of ASThma study were followed prospectively from birth. Blood samples were collected at ages 2, 4, 6, and 11 years, and serum-specific IgE levels, blood eosionophil counts, and periostin levels were measured in 244 children. Relationships among these biomarkers, age, and asthma were assessed.

RESULTS

Serum periostin levels were approximately 2- to 3-fold higher in children than previously observed adult levels. Levels were highest at 2 years (145 ng/mL), and did not change significantly between 4 and 11 years (128 and 130 ng/mL). Age 2 year periostin level of 150 ng/mL or more predicted asthma at age 6 years (odds ratio [OR], 2.3; 95% CI, 1.3-4.4). Eosinophil count of 300 cells/μL or more and aeroallergen sensitization at age 2 years were each associated with increased risk of asthma at age 6 years (OR, 3.1; 95% CI, 1.7-6.0 and OR, 3.3; 95% CI, 1.7-6.3). Children with any 2 of the biomarkers had a significantly increased risk of developing asthma by school age (≥2 biomarkers vs none: OR, 6.6; 95% CI, 2.7-16.0).

CONCLUSIONS

Serum periostin levels are significantly higher in children than in adults, likely due to bone turnover, which impairs clinical utility in children. Early life aeroallergen sensitization and elevated blood eosinophils are robust predictors of asthma development. Children with evidence of activation of multiple pathways of type 2 inflammation in early life are at greatest risk for asthma development.

A systematic review of predictive models for asthma development in children

BACKGROUND

Asthma is the most common pediatric chronic disease affecting 9.6 % of American children. Delay in asthma diagnosis is prevalent, resulting in suboptimal asthma management. To help avoid delay in asthma diagnosis and advance asthma prevention research, researchers have proposed various models to predict asthma development in children. This paper reviews these models.

METHODS

A systematic review was conducted through searching in PubMed, EMBASE, CINAHL, Scopus, the Cochrane Library, the ACM Digital Library, IEEE Xplore, and OpenGrey up to June 3, 2015. The literature on predictive models for asthma development in children was retrieved, with search results limited to human subjects and children (birth to 18 years). Two independent reviewers screened the literature, performed data extraction, and assessed article quality.

RESULTS

The literature search returned 13,101 references in total. After manual review, 32 of these references were determined to be relevant and are discussed in the paper. We identify several limitations of existing predictive models for asthma development in children, and provide preliminary thoughts on how to address these limitations.

CONCLUSIONS

Existing predictive models for asthma development in children have inadequate accuracy. Efforts to improve these models' performance are needed, but are limited by a lack of a gold standard for asthma development in children.

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.

A systematic review of predictive modeling for bronchiolitis

PURPOSE

Bronchiolitis is the most common cause of illness leading to hospitalization in young children. At present, many bronchiolitis management decisions are made subjectively, leading to significant practice variation among hospitals and physicians caring for children with bronchiolitis. To standardize care for bronchiolitis, researchers have proposed various models to predict the disease course to help determine a proper management plan. This paper reviews the existing state of the art of predictive modeling for bronchiolitis. Predictive modeling for respiratory syncytial virus (RSV) infection is covered whenever appropriate, as RSV accounts for about 70% of bronchiolitis cases.

METHODS

A systematic review was conducted through a PubMed search up to April 25, 2014. The literature on predictive modeling for bronchiolitis was retrieved using a comprehensive search query, which was developed through an iterative process. Search results were limited to human subjects, the English language, and children (birth to 18 years).

RESULTS

The literature search returned 2312 references in total. After manual review, 168 of these references were determined to be relevant and are discussed in this paper. We identify several limitations and open problems in predictive modeling for bronchiolitis, and provide some preliminary thoughts on how to address them, with the hope to stimulate future research in this domain.

CONCLUSIONS

Many problems remain open in predictive modeling for bronchiolitis. Future studies will need to address them to achieve optimal predictive models.

Eosinophil-derived neurotoxin levels at 3 months post-respiratory syncytial virus bronchiolitis are a predictive biomarker of recurrent wheezing

OBJECTIVE

To determine whether eosinophil-derived neurotoxin (EDN) is a predictive marker of recurrent wheezing episodes in post-respiratory syncytial virus (RSV) bronchiolitis.

METHODS

EDN levels and recurrent wheezing episodes were serially measured in 200 infants hospitalized with RSV bronchiolitis.

RESULTS

Serum EDN levels at 3 months correlated significantly with total wheezing episodes at 12 months in the RSV-PLC (n  = 71; r = 0.720, p < 0.0001) and RSV-MONT groups (n = 79; r = 0.531, p < 0.001). Positive predictive value of 3-mo EDN level for total wheezing episodes was 57%; negative predictive value, 76%; sensitivity, 72%; specificity, 62%.

CONCLUSION

EDN levels have predictive value for the development of recurrent wheezing post-RSV bronchiolitis.

Infection, eosinophilia and childhood asthma

There is a growing list of viruses and bacteria associated with wheezing illness and asthma. It is well known that a few of these pathogens are strongly associated with wheezing illness and asthma exacerbations. What is not known is if early childhood infections with these pathogens cause asthma, and, if so, exactly what are the pathophysiologic mechanisms behind its development. The current consensus is respiratory infection works together with allergy to produce the immune and physiologic conditions necessary for asthma diasthesis. One link between respiratory infection and asthma may be the eosinophil, a cell that plays prominently in asthma and allergy, but can also be found in the body in response to infection. In turn, the eosinophil and its associated products may be novel therapeutic targets, or at the very least used to elucidate the complex pathophysiologic pathways of asthma and other respiratory illnesses. Together or separately, they can also be used for diagnosis, treatment and monitoring. The optimal care of a patient must take into consideration not only symptoms, but also the underlying disease mechanisms.

A simple tool to identify infants at high risk of mild to severe childhood asthma: the persistent asthma predictive score

BACKGROUND

Recurrent wheezing in infants is a recognized risk factor for the development of childhood asthma. We sought to develop an easy-to-use persistent asthma predictive score (PAPS) in a population of young recurrent wheezers.

METHODS

We retrospectively studied clinical and biological data of infants under 2 years of age presenting recurrent wheezing and evaluated current asthma at 6 years of age using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. Multivariate analysis was performed to select predictive variables to generate a PAPS. The score was then tested on another cohort for independent validation.

RESULTS

Two hundred infants were included in the cohort used to create the PAPS, and 227 in the validation cohort. In the first population, 47% of the children had developed asthma at 6 years of age, including 33% with mild to severe persistent asthma. Three parameters independently predicted persistent asthma: family history of asthma, personal atopic dermatitis, and multiple allergen sensitizations. Based on these variables, the PAPS showed 42% sensitivity, 90% specificity, 67% positive predictive value, and 76% negative predictive value for the prediction of persistent asthma. It was able to discriminate future persistent asthmatic from nonfuture persistent asthmatic children, with an accuracy of 74% in the initial population and 67% in the validation population.

CONCLUSIONS

The PAPS, based on three easy-to-obtain variables, could help the physician in clinical practice to identify infants at high risk for persistent childhood asthma, and thus better evaluate the need for secondary preventive measures.

Predicting the long-term course of asthma in wheezing infants is still a challenge

Background. In recurrent wheezing infants, it is important to identify those likely to remain asthmatic in order to propose appropriate long-term management. Objective. To establish predictive factors for persistent asthma at adolescence in a population of recurrent wheezing infants. Methods. Retrospective study of 227 infants. Inclusion criteria were age under 36 months, a history of at least three wheezing episodes assessed via a doctor-led ISAAC questionnaire and a standardized allergy testing programme. At 13 years, active asthma was assessed by questionnaire. Results. Risk factors for asthma persisting into adolescence were allergic sensitization to multiple airborne allergens (OR 4.6, CI-95% (1.9–11.2) P = 0.001), initial atopic dermatitis (OR 3.4, CI-95% (1.9–6.3) P < 0.001), severe recurrent wheezing (OR 2.3, CI-95% (1.3–4.2) P = 0.007), and hypereosinophilia ≥470/mm³ (OR 2.2, CI-95% (1.07–4.7) P = 0.033). Conclusion. While it is still difficult to predict the long-term course of asthma, atopy remains the major risk factor for persistent asthma.

Respiratory viruses, eosinophilia and their roles in childhood asthma

With the advent of highly sensitive and specific screening of respiratory specimens for viruses, new viruses are discovered, adding to the growing list of those associated with wheezing illness and asthma exacerbations. It is not known whether early childhood infections with these viruses cause asthma, and, if so, what exactly are the pathophysiologic mechanisms behind its development. The current consensus is that respiratory viral infection works together with allergy to produce the immune and physiologic conditions necessary for asthma diasthesis. One link between viruses and asthma may be the eosinophil, a cell that plays a prominent role in asthma and allergy, but can also be found in the body in response to viral infection. In turn, the eosinophil and its associated products may be novel therapeutic targets, or at the very least, used to elucidate the complex pathophysiologic pathways of asthma and other respiratory illnesses. Together or separately, they can be used for diagnosis, treatment and monitoring. Not only symptoms, but also the underlying disease mechanisms must be taken into consideration for the optimal care of a patient.

Immunomodulation with IL-4R alpha antisense oligonucleotide prevents respiratory syncytial virus-mediated pulmonary disease

Respiratory syncytial virus (RSV) causes significant morbidity and mortality in infants worldwide. Severe RSV infections in infants cause bronchiolitis, wheeze, and/or cough and significantly increase the risk for developing asthma. RSV pathogenesis is thought to be due to a Th2-type immune response initiated in response to RSV infection, specifically in the infant. Using a neonatal mouse system as an appropriate model for human infants, we sought to determine whether local inhibition of IL-4Rα expression during primary RSV infection in the neonate would prevent Th2-skewed responses to secondary RSV infection and improve long-term pulmonary function. To reduce IL-4Rα expression, antisense oligonucleotides (ASOs) specific for IL-4Rα were administered intranasally to neonatal mice at the time of primary infection. Mice were initially infected with RSV at 1 wk of age and were reinfected at 6 wk of age. Administration of IL-4Rα ASOs during primary RSV infection in neonatal mice abolished the pulmonary dysfunction normally observed following reinfection in the adult. This ablation of pulmonary dysfunction correlated with a persistent rebalancing of the Th cell compartment with decreased Th2 responses (i.e., reduced goblet cell hyperplasia, Th2 cells, and cytokine secretion) and increased Th1 responses (i.e., elevated Th1 cell numbers and type I Abs and cytokines). Our data support our hypothesis that a reduction in the Th2 immune response during primary infection in neonates prevents Th2-mediated pulmonary pathology initially and upon reinfection and further suggest that vaccine strategies incorporating IL-4Rα ASOs may be of significant benefit to infants.

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.

[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.

Eosinophil activity in infants hospitalized for wheezing and risk of persistent childhood asthma

Eosinophilic inflammation has a central role in the pathogenesis of asthma. We aimed to elucidate whether elevated blood eosinophil count (B-EOS), eosinophil cationic protein in serum (S-ECP) or in nasopharyngeal aspirate (NPA-ECP) predict later asthma after hospitalization for wheezing in infancy. In 1992-1993, 100 infants aged <24 months were hospitalized for wheezing associated with respiratory infection. B-EOS, S-ECP and NPA-ECP were measured on admission. Asthma status was evaluated at the follow-up visits at the median ages of 4.0, 7.2 and 12.3 yr. Twenty (25%) of 81 children had asthma at all three visits and were considered to have persistent childhood asthma (PCA). Children with B-EOS >or= 0.450 x 10(9) cells/l had a 2.9-fold PCA risk compared with other children. The risk was 6.1-fold when S-ECP was >or=20.0 microg/l and 6.7-fold when NPA-ECP was >or=815.0 ng/g. By these cut-off limits, all these markers were specific (75-93%), but not very sensitive (30-58%) in predicting PCA. At least one marker was elevated in 75% of the children with PCA. The respective figure for NPA-ECP alone was 58%. In adjusted analyses, only elevated NPA-ECP was an independent risk factor for PCA (OR 4.09). In conclusion, eosinophil activity in early life predicts the development of childhood asthma after hospitalization for wheezing in infancy. The results highlight NPA-ECP as an independent predictor of the persistence of asthma at school age.

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.

[Biological markers in acute bronchiolitis: Correlations with gravity and risk factors for asthma]

La bronchiolite aiguë est une infection virale respiratoire épidémique du nourrisson. Le virus respiratoire syncytial est l’agent infectieux le plus fréquent au cours des bronchiolites. D’autres virus sont retrouvés, seuls ou en co-infections virales. Ce travail est une étude dont le but est de rechercher un ou des marqueurs biologiques prédictifs de la gravité d’un épisode de bronchiolite aiguë et de l’évolution vers un asthme du nourrisson, dans le cadre du protocole Bronchiolite (PHRC 2000 n^o 2000/020/HP), étude de cohorte, prospective, multicentrique, réalisée de novembre 2001 à janvier 2006. Sept centres ont participé : Rouen, Le Havre, Lille, Elbeuf, Evreux, Brest et Saint-Nazaire en association avec Nantes. Les données clinicobiologiques étaient recueillies au cours de l’hospitalisation initiale, puis lors des visites suivantes à un mois et à un an. Ainsi, 209 nourrissons âgés en moyenne de trois mois ont été suivis avec une évaluation de la gravité sur des critères cliniques. Les résultats de laboratoires ont été corrélés aux éléments de gravité pour les résultats suivants : identification virale, numération des leucocytes, lymphocytes et éosinophiles, étude en cytométrie en flux de populations lymphocytaires et allergologie incluant les IgE, l’eosinophilic cationic protein et test d’activation des basophiles. Les résultats de cette étude sont présentés et discutés.

[Biological markers in acute bronchiolitis: correlations with gravity and risk factors for asthma]

La bronchiolite aiguë est une infection virale respiratoire épidémique du nourrisson. Le virus respiratoire syncytial est l’agent infectieux le plus fréquent au cours des bronchiolites. D’autres virus sont retrouvés, seuls ou en co-infections virales. Ce travail est une étude dont le but est de rechercher un ou des marqueurs biologiques prédictifs de la gravité d’un épisode de bronchiolite aiguë et de l’évolution vers un asthme du nourrisson, dans le cadre du protocole Bronchiolite (PHRC 2000 n° 2000/020/HP), étude de cohorte, prospective, multicentrique, réalisée de novembre 2001 à janvier 2006. Sept centres ont participé : Rouen, Le Havre, Lille, Elbeuf, Évreux, Brest et Saint-Nazaire en association avec Nantes. Les données clinico-biologiques étaient recueillies au cours de l’hospitalisation initiale, puis lors des visites suivantes à un mois et à un an. Ainsi 209 nourrissons âgés en moyenne de 3 mois ont été suivis avec une évaluation de la gravité sur des critères cliniques. Les résultats de laboratoires ont été corrélés aux éléments de gravité pour les résultats suivants : identification virale, numération des leucocytes, lymphocytes et éosinophiles, étude en cytométrie en flux de populations lymphocytaires et allergologie incluant les IgE, l’eosinophil cationic protein et test d’activation des basophiles. Les résultats de cette étude sont présentés et discutés.

Presence of eosinophils in nasal secretion during acute respiratory tract infection in young children predicts subsequent wheezing within two months

BACKGROUND

In young children with wheezing or bronchiolitis, especially with respiratory syncitial virus, blood eosinophilia and a high eosinophil cationic protein level in nasal secretions predicts subsequent wheezing in later childhood. However, whether eosinophil activation results from virus-induced inflammation or local eosinophilia per se precedes the onset of wheezing remains unknown. In the present study, we examined the association between the presence of nasal eosinophils during respiratory tract infection (RTI) and subsequent wheezing in young children.

METHODS

A total of 35 young children less than 3 years of age who visited our outpatient clinic with rhinorrhea between April and July 2004 were enrolled in this prospective cohort study. Subjects who were given diagnoses of allergic rhinitis were excluded. In all the subjects, the presence of eosinophils in nasal secretions was determined. The subjects were followed, and the cumulative incidences of wheezing during the subsequent 2- and 12-month periods were examined.

RESULTS

According to a logistic regression analysis adjusted for age, sex, family history, allergies, and wheezing at entry, young children with nasal eosinophil infiltration during acute RTI had a significantly higher risk of wheezing during the subsequent 2 months, compared with those without nasal eosinophil infiltration (adjusted odds ratio, 27.618, p = 0.016).

CONCLUSIONS

Our findings not only suggest that nasal eosinophil testing may serve as a convenient clinical marker for identifying young children at risk for subsequent wheezing, but also shed new light on the role of eosinophils in the onset of wheezing in young children.

Lack of eosinophilia can predict remission in wheezy infants?

BACKGROUND

Early wheezing in infants is a potential risk factor for persistence of asthma into adulthood. Moreover, a personal or familial history of atopy are risk factors associated with persistence of pre-existing wheezing during childhood. However, their relative importance remains unclear.

OBJECTIVES

Firstly to determine the critical thresholds of common biological markers of atopy in wheezy infants associated with persistence of wheezing into childhood and secondly to rank these biological markers together with clinical parameters according to the strength of their association with wheezing persistence.

METHODS

A cohort of infants less than 30 months old with recurrent wheezing was established in order to assess severity of respiratory symptoms and to look for the presence of atopy. At the age of 6 years, they were re-evaluated regarding remission of wheezing over the previous 12-months period.

RESULTS

Data were available for 219 subjects. In 27% of them, wheezing persisted at 6 years of age. Critical biological thresholds associated with the risk of wheezing persistence were: (1) a blood eosinophilia count >or=470/mm(3) (defining eosinophilia), and (2) a total serum IgE level >or=45 IU/mL (defining elevated IgE) during infancy. A multiple component factorial analysis identified a dimension associating eosinophilia, elevated IgE and allergic sensitization on the one hand with persistent wheezing at 6 years of age on the other (lambda=0.15). According to a segmentation analysis, the main discriminative parameter of wheezing persistence was eosinophilia. Thus a lack of eosinophilia alone could account for 91% of infants in remission, and when combined with absence of allergic sensitization, remission was correctly discriminated in 96.9% of the study population.

CONCLUSION

Our data strongly suggest that the lack of eosinophilia in wheezy infants without ongoing infection could predict future remission of wheezing in a large majority of cases.

Wheezy babies--wheezy adults? Review on long-term outcome until adulthood after early childhood wheezing

Population-based birth cohort studies have documented that about 30% of children suffer from wheezing during respiratory infection before their third birthday. Recurrent wheezing is common in early childhood, but most patients outgrow their symptoms by school age. However, recent long-term postbronchiolitis follow-up studies from Sweden and Finland have revealed that asthma is present in about 40% of young adults and over half of the cases are relapses after many symptom-free years. In population studies, the principal predictors for later asthma have been parental asthma, recurrent wheezing, atopy and eosinophilia. In the Swedish postbronchiolitis study, atopic diathesis through the development of clinical atopy, and early passive smoking through bronchial hyper-reactivity or later active smoking led to adult asthma. The Finnish postbronchiolitis follow-up stressed early recurrence of wheezing, wheezing induced by less invasive viruses than respiratory syncytial virus (RSV), early-life atopy and eosinophilia and parental asthma as predictors for adult asthma.

CONCLUSION

The majority of wheezing infants and children outgrow their symptoms by school age, but based on recent long-term follow-up studies, asthma relapses are common in young adults. These studies have highlighted parental asthma, maternal smoking and wheezing induced by other viruses than RSV as predictive factors for later asthma.