The Prevention of Early Asthma in Kids study: design, rationale and methods for the Childhood Asthma Research and Education network

Resequencing candidate genes implicates rare variants in asthma susceptibility

Common variation in over 100 genes has been implicated in the risk of developing asthma, but the contribution of rare variants to asthma susceptibility remains largely unexplored. We selected nine genes that showed the strongest signatures of weak purifying selection from among 53 candidate asthma-associated genes, and we sequenced the coding exons and flanking noncoding regions in 450 asthmatic cases and 515 nonasthmatic controls. We observed an overall excess of p values <0.05 (p = 0.02), and rare variants in four genes (AGT, DPP10, IKBKAP, and IL12RB1) contributed to asthma susceptibility among African Americans. Rare variants in IL12RB1 were also associated with asthma susceptibility among European Americans, despite the fact that the majority of rare variants in IL12RB1 were specific to either one of the populations. The combined evidence of association with rare noncoding variants in IL12RB1 remained significant (p = 3.7 × 10(-4)) after correcting for multiple testing. Overall, the contribution of rare variants to asthma susceptibility was predominantly due to noncoding variants in sequences flanking the exons, although nonsynonymous rare variants in DPP10 and in IL12RB1 were associated with asthma in African Americans and European Americans, respectively. This study provides evidence that rare variants contribute to asthma susceptibility. Additional studies are required for testing whether prioritizing genes for resequencing on the basis of signatures of purifying selection is an efficient means of identifying novel rare variants that contribute to complex disease.

Daily or intermittent budesonide in preschool children with recurrent wheezing

BACKGROUND

Daily inhaled glucocorticoids are recommended for young children at risk for asthma exacerbations, as indicated by a positive value on the modified asthma predictive index (API) and an exacerbation in the preceding year, but concern remains about daily adherence and effects on growth. We compared daily therapy with intermittent therapy.

METHODS

We studied 278 children between the ages of 12 and 53 months who had positive values on the modified API, recurrent wheezing episodes, and at least one exacerbation in the previous year but a low degree of impairment. Children were randomly assigned to receive a budesonide inhalation suspension for 1 year as either an intermittent high-dose regimen (1 mg twice daily for 7 days, starting early during a predefined respiratory tract illness) or a daily low-dose regimen (0.5 mg nightly) with corresponding placebos. The primary outcome was the frequency of exacerbations requiring oral glucocorticoid therapy.

RESULTS

The daily regimen of budesonide did not differ significantly from the intermittent regimen with respect to the frequency of exacerbations, with a rate per patient-year for the daily regimen of 0.97 (95% confidence interval [CI], 0.76 to 1.22) versus a rate of 0.95 (95% CI, 0.75 to 1.20) for the intermittent regimen (relative rate in the intermittent-regimen group, 0.99; 95% CI, 0.71 to 1.35; P=0.60). There were also no significant between-group differences in several other measures of asthma severity, including the time to the first exacerbation, or adverse events. The mean exposure to budesonide was 104 mg less with the intermittent regimen than with the daily regimen.

CONCLUSIONS

A daily low-dose regimen of budesonide was not superior to an intermittent high-dose regimen in reducing asthma exacerbations. Daily administration led to greater exposure to the drug at 1 year. (Funded by the National Heart, Lung, and Blood Institute and others; MIST ClinicalTrials.gov number, NCT00675584.).

Decreased lung function after preschool wheezing rhinovirus illnesses in children at risk to develop asthma

Background

Preschool rhinovirus (RV) wheezing illnesses predict an increased risk of childhood asthma; however, it is not clear how specific viral illnesses in early life relate to lung function later on in childhood.

Objective

To determine the relationship of virus-specific wheezing illnesses and lung function in a longitudinal cohort of children at risk for asthma.

Methods

Two hundred thirty-eight children were followed prospectively from birth to 8 years of age. Early life viral wheezing respiratory illnesses were assessed by using standard techniques, and lung function was assessed annually by using spirometry and impulse oscillometry. The relationships of these virus-specific wheezing illnesses and lung function were assessed by using mixed-effect linear regression.

Results

Children with RV wheezing illness demonstrated significantly decreased spirometry values, FEV₁ (P = .001), FEV_0.5 (P < .001), FEF_25-75 (P < .001), and also had abnormal impulse oscillometry measures—more negative reactance at 5 Hz (P < .001)—compared with those who did not wheeze with RV. Children who wheezed with respiratory syncytial virus or other viral illnesses did not have any significant differences in spirometric or impulse oscillometry indices when compared with children who did not. Children diagnosed with asthma at ages 6 or 8 years had significantly decreased FEF_25-75 (P = .05) compared with children without asthma.

Conclusion

Among outpatient viral wheezing illnesses in early childhood, those caused by RV infections are the most significant predictors of decreased lung function up to age 8 years in a high-risk birth cohort. Whether low lung function is a cause and/or effect of RV wheezing illnesses is yet to be determined.

Identification of ATPAF1 as a novel candidate gene for asthma in children

BACKGROUND

Asthma is a common disease of children with a complex genetic origin. Understanding the genetic basis of asthma susceptibility will allow disease prediction and risk stratification.

OBJECTIVE

We sought to identify asthma susceptibility genes in children.

METHODS

A nested case-control genetic association study of children of Caucasian European ancestry from a birth cohort was conducted. Single nucleotide polymorphisms (SNPs, n = 116,024) were genotyped in pools of DNA samples from cohort children with physician-diagnosed asthma (n = 112) and normal controls (n = 165). A genomic region containing the ATPAF1 gene was found to be significantly associated with asthma. Additional SNPs within this region were genotyped in individual samples from the same children and in 8 independent study populations of Caucasian, African American, Hispanic, or other ancestries. SNPs were also genotyped or imputed in 2 consortia control populations. ATPAF1 expression was measured in bronchial biopsies from asthmatic patients and controls.

RESULTS

Asthma was found to be associated with a cluster of SNPs and SNP haplotypes containing the ATPAF1 gene, with 2 SNPs achieving significance at a genome-wide level (P = 2.26 × 10(-5) to 2.2 × 10(-8)). Asthma severity was also found to be associated with SNPs and SNP haplotypes in the primary population. SNP and/or gene-level associations were confirmed in the 4 non-Hispanic populations. Haplotype associations were also confirmed in the non-Hispanic populations (P = .045-.0009). ATPAF1 total RNA expression was significantly (P < .01) higher in bronchial biopsies from asthmatic patients than from controls.

CONCLUSION

Genetic variation in the ATPAF1 gene predisposes children of different ancestries to asthma.

Approaches to stepping up and stepping down care in asthmatic patients

The variability in symptom control is a challenging feature of asthma that necessitates careful monitoring and the need to step up and step down individualized therapeutic regimens over time. This stepwise concept in asthma therapy can be considered in at least 3 contexts. For lack of control that is persistent over long periods of time, an increase in the overall medication or a step-up long-term strategy is indicated. A second approach, the step-up short-term strategy, can be used during a temporary loss of acceptable control, such as at the onset of a viral respiratory tract illness. In these cases a step-up in therapy is usually terminated in 3 to 10 days once asthma control has been satisfactorily achieved. Finally, for treating symptoms related to the variability of asthma on a day-to-day basis, inhaled corticosteroids used concomitantly with a β-agonist have been evaluated, although this treatment is not currently approved in the United States. We will term this particular intervention a step-up intermittent strategy. Here we summarize the existing data regarding these 3 approaches to step up care and step down management, as well as to identify areas where more comparative studies are necessary to provide further guidance to clinicians regarding proper step-up and step-down strategies in the care of asthma.

House dust mite sensitization in toddlers predicts current wheeze at age 12 years

BACKGROUND

Identification of children at risk of developing asthma provides a window of opportunity for risk-reducing interventions. Allergen sensitization might identify high-risk children.

OBJECTIVE

We sought to determine whether skin prick tests (SPTs) to individual allergens up to age 2 years predict wheeze at age 12 years.

METHODS

In a birth cohort of 620 children oversampled for familial allergy, sensitization was assessed by using SPTs (monosensitized, polysensitized, or either) to 6 allergens at ages 6, 12, and 24 months. Wheeze and eczema were recorded 18 times during the first 2 years. Current wheeze was recorded at age 12 years. Adjusted associations were evaluated by multiple logistic regression.

RESULTS

A positive SPT to house dust mite (HDM) at age 1 or 2 years predicted wheeze at age 12 years (adjusted odds ratio: 1 year, 3.31 [95% CI 1.59-6.91]; 2 years, 6.37 [95% CI, 3.48-11.66]). Among wheezy 1-year-olds, those who were HDM sensitized had a 75% (95% CI, 51% to 91%) probability of wheeze at age 12 years compared with a 36% (95% CI, 23% to 50%) probability among those not sensitized. Among eczematous 1-year-olds, those who were HDM sensitized had a 67% (95% CI, 45% to 84%) probability of wheeze at age 12 years compared with a 35% (95% CI, 25% to 45%) probability among those not sensitized. Among 1-year-old children with both eczema and wheeze, the probability of wheeze at age 12 years was 64% (95% CI, 35% to 87%) if HDM sensitized and 50% (95% CI, 26% to 74%) if not.

CONCLUSION

HDM sensitization at age 1 or 2 years in wheezing and eczematous children at increased familial allergy risk predicts asthma and may inform management of these high-risk groups.

Growth of preschool children at high risk for asthma 2 years after discontinuation of fluticasone

BACKGROUND

The effect on linear growth of daily long-term inhaled corticosteroid therapy in preschool-aged children with recurrent wheezing is controversial.

OBJECTIVE

We sought to determine the effect of daily inhaled corticosteroid given for 2 years on linear growth in preschool children with recurrent wheezing.

METHODS

Children aged 2 and 3 years with recurrent wheezing and positive modified Asthma Predictive Index scores were randomized to a 2-year treatment period of chlorofluorocarbon-delivered fluticasone propionate (176 μg/d) or masked placebo delivered through a valved chamber with a mask and then followed for 2 years off study medication. Height growth determined by means of stadiometry was compared between treatment groups.

RESULTS

In the study cohort as a whole, the fluticasone group did not have significantly less linear growth than the placebo group (change in height from baseline difference, -0.2 cm; 95% CI, -1.1 to 0.6) 2 years after discontinuation of study treatment. In post hoc analyses children 2 years old who weighed less than 15 kg at enrollment and were treated with fluticasone had less linear growth compared with those treated with placebo (change in height from baseline difference, -1.6 cm; 95% CI, -2.8 to -0.4; P = .009).

CONCLUSION

Linear growth was not significantly different in high-risk preschool-aged children with recurrent wheezing treated with 176 μg/d chlorofluorocarbon-delivered fluticasone compared with placebo 2 years after fluticasone is discontinued. However, post hoc subgroup analyses revealed that children who are younger in age and of lesser weight relative to the entire study cohort had significantly less linear growth, possibly because of a higher relative fluticasone exposure.

Inhaled Corticosteroids Should Be Used in Infants and Preschoolers with Recurrent Wheezing

The infant or child presenting to the physician's office with persistent or recurrent wheezing during the first 2 years of life poses, often times, a diagnostic dilemma, and a therapeutic challenge. Until very recently, no guidelines were present to help the clinician navigate the very limited treatment options. The diagnosis of asthma in the very young is primarily difficult because of the lack of consistency of what is called asthma, and the failure to recognize the different phenotypes of asthma at different ages. Many classification and phenotypic descriptions have been proposed, but they continue to cause more confusion to already confused parents and perplexed physicians. Although these studies have provided much insight into the natural history of wheezy disorders, they have failed to affect clinical management to a large extent. Controversy persists as to when and why and how long inhaled corticosteroids (ICS) should be used in wheezy infants. Based on the current knowledge in this age group, ICS seems to be indicated in infants with multi-triggers wheeze, and in infants with a positive asthma predictive index. This article reviews the different phenotypic presentations of wheezy infant, the role and indications of ICS in this situation, and, finally, suggests a treatment plan based on the apparent cause of wheezing.

The differential diagnosis and management of asthma in the preschool-aged child

PURPOSE

To discuss the diagnosis and management of asthma in preschool-aged children by nurse practitioners in primary care.

DATA SOURCES

Selected research and clinical articles; 2007 National Asthma Education and Prevention Program Guidelines for the Diagnosis and Management of Asthma.

CONCLUSIONS

Proper diagnosis leads to appropriate treatment of asthma in preschool-aged children, which facilitates asthma control. Well-controlled asthma results in fewer asthma exacerbations, fewer nighttime awakenings, and an increased ability to engage in normal childhood activities.

IMPLICATIONS FOR PRACTICE

Advanced practice nurses are in the position to aid in the initial diagnosis of asthma in preschool-aged children through taking detailed medical histories, providing thorough physical examinations, and, if needed, initiating a therapeutic trial with an inhaled corticosteroid. Proper diagnosis and management of asthma is essential to reduce asthma complications, such as exacerbations leading to emergency department visits and hospitalizations.

Global strategy for the diagnosis and management of asthma in children 5 years and younger

Asthma is the most common chronic disease of childhood and the leading cause of childhood morbidity from chronic disease as measured by school absences, emergency department visits, and hospitalisation. During the past two decades, many scientific advances have improved our understanding of asthma and our ability to manage and control it effectively. However, in children 5 years and younger, the clinical symptoms of asthma are variable and non-specific. Furthermore, neither airflow limitation nor airway inflammation, the main pathologic hallmarks of the condition, can be assessed routinely in this age group. For this reason, to aid in the diagnosis of asthma in young children, a symptoms-only descriptive approach that includes the definition of various wheezing phenotypes has been recommended. In 1993, the Global Initiative for Asthma (GINA) was implemented to develop a network of individuals, organizations, and public health officials to disseminate information about the care of patients with asthma while at the same time assuring a mechanism to incorporate the results of scientific investigations into asthma care. Since then, GINA has developed and regularly revised a Global Strategy for Asthma Management and Prevention. Publications based on the Global Strategy for Asthma Management and Prevention have been translated into many different languages to promote international collaboration and dissemination of information. In this report, Global Strategy for Asthma Management and Prevention in Children 5 Years and Younger, an effort has been made to present the special challenges that must be taken into account in managing asthma in children during the first 5 years of life, including difficulties with diagnosis, the efficacy and safety of drugs and drug delivery systems, and the lack of data on new therapies. Approaches to these issues will vary among populations in the world based on socioeconomic conditions, genetic diversity, cultural beliefs, and differences in healthcare access and delivery. Patients in this age group are often managed by pediatricians and general practitioners routinely faced with a wide variety of issues related to childhood diseases.

Uniform definition of asthma severity, control, and exacerbations: document presented for the World Health Organization Consultation on Severe Asthma

Asthma is a global health problem affecting around 300 million individuals of all ages, ethnic groups and countries. It is estimated that around 250,000 people die prematurely each year as a result of asthma. Concepts of asthma severity and control are important in evaluating patients and their response to treatment, as well as for public health, registries, and research (clinical trials, epidemiologic, genetic, and mechanistic studies), but the terminology applied is not standardized, and terms are often used interchangeably. A common international approach is favored to define severe asthma, uncontrolled asthma, and when the 2 coincide, although adaptation may be required in accordance with local conditions. A World Health Organization meeting was convened April 5-6, 2009, to propose a uniform definition of severe asthma. An article was written by a group of experts and reviewed by the Global Alliance against Chronic Respiratory Diseases review group. Severe asthma is defined by the level of current clinical control and risks as "Uncontrolled asthma which can result in risk of frequent severe exacerbations (or death) and/or adverse reactions to medications and/or chronic morbidity (including impaired lung function or reduced lung growth in children)." Severe asthma includes 3 groups, each carrying different public health messages and challenges: (1) untreated severe asthma, (2) difficult-to-treat severe asthma, and (3) treatment-resistant severe asthma. The last group includes asthma for which control is not achieved despite the highest level of recommended treatment and asthma for which control can be maintained only with the highest level of recommended treatment.

Relationship between silent gastroesophageal reflux and food sensitization in infants and young children with recurrent wheezing

It is known that early childhood wheezing associated with sensitization to allergens, including food, has an increased risk of developing asthma later during school age. Gastroesophageal reflux (GER) is well known to be associated with asthma. The purpose of this study was to determine whether there is an association between silent GER and food sensitization in infants and young children with recurrent wheezing. Eighty-five infants or young children with recurrent wheezing, and no gastrointestinal symptoms, underwent 24 hr esophageal pH monitoring, as well as total serum IgE and specific IgE testing for eggs and milk. Among the 85 subjects, 48.2% had significant GER. There was no significant difference in the GER between atopic and non-atopic recurrent wheezers (41.7% and 50.8%, respectively). The sensitization rate to food (eggs or milk) was 12.2% and 20.5% in the GER and non-GER groups, respectively and showed no statistically significant difference between the two groups (P=0.34). In conclusion, about half of infants and young children with recurrent wheezing and no gastrointestinal symptoms have silent GER. The silent GER may not contribute to food sensitization in infants and young children with recurrent wheezing.

Relationship between infant weight gain and later asthma

Like obesity, the prevalence of asthma has increased over the past several decades. Accelerated patterns of infant growth have been associated with obesity and its co-morbidities. We aimed to determine if infant weight gain pattern is associated with asthma development later in childhood. Birth weight, growth, pulmonary function, and symptom data were collected in a trial of 2- to 3-yr-old children at-risk for asthma randomized to a 2-yr treatment with inhaled corticosteroids or placebo followed by a 1-yr observation period of study medication. Patterns of infant weight gain between birth and study enrollment were categorized as accelerated, average, or decelerated. Regression analyses were used to test the effects of infant weight gain pattern prior to study enrollment on outcomes during the observation year and at study conclusion while adjusting for demographics, baseline symptom severity, study treatment, and atopic indicators. Among the 197 study participants, early life weight gain pattern was not associated with daily asthma symptoms or lung function at the study's conclusion. However, both prednisone courses (p = 0.01) and urgent physician visits (p < 0.001) were significantly associated with weight gain pattern with fewer exacerbations occurring amongst those with a decelerated weight gain pattern. We conclude that early life patterns of weight change were associated with subsequent asthma exacerbations, but were not associated with asthma symptoms or pulmonary function during the pre-school years for these children at-risk for asthma.

Asthma therapies revisited: what have we learned?

Asthma is a heterogenous disorder related to numerous biologic, immunologic, and physiologic components that generate multiple clinical phenotypes. Further, genetic and environmental factors interact in ways that produce variability in both disease onset and severity and differential expression based on both the age and sex of the patient. Thus, the natural history of asthma is complex in terms of disease expression, remission, relapse, and progression. As such, therapy for asthma is complicated and has been approached from the standpoints of primary, secondary, and tertiary prevention. Presently, asthma cannot be cured but can be controlled in most patients, an indication that most of the success clinical research strategies have realized has been in the area of tertiary prevention. Since for many adult patients with asthma their disease had its roots in early life, much recent research has focused on events during early childhood that can be linked to subsequent asthma development with the hopes of creating appropriate interventions to alter its natural history of expression. These research approaches can be categorized into three questions. Who is the right patient to treat? When is the right time to begin treatment? And finally, what is the appropriate treatment to prescribe?

Patient characteristics associated with improved outcomes with use of an inhaled corticosteroid in preschool children at risk for asthma

BACKGROUND

Maintenance inhaled corticosteroid (ICS) therapy in preschool children with recurrent wheezing at high-risk for development of asthma produces multiple clinical benefits. However, determination of baseline features associated with ICS responsiveness may identify children most likely to benefit from ICS treatment.

OBJECTIVE

To determine if demographic and atopic features predict response to ICS in preschool children at high risk for asthma.

METHODS

Two years of treatment with an ICS, fluticasone propionate (88 microg twice daily), was compared with matching placebo in a double-masked, randomized, multicenter study of 285 children 2 and 3 years old at high risk for asthma development. Baseline demographic and atopic features were related to clinical outcomes in a post hoc subgroup analysis.

RESULTS

Multivariate analysis demonstrated significantly greater improvement with fluticasone than placebo in terms of episode-free days among boys, white subjects, participants with an emergency department (ED) visit or hospitalization within the past year, and those who experienced more symptomatic days at baseline. Children with aeroallergen sensitization experienced greater benefits in terms of oral corticosteroid use, urgent care and ED visits, and use of supplemental controller medications.

CONCLUSIONS

More favorable responses to ICS than placebo in high-risk preschool children over a 2-year period were more likely in those with a ED visit or hospitalization for asthma within the past year, children with aeroallergen sensitization, boys, and white subjects.

Episodic use of an inhaled corticosteroid or leukotriene receptor antagonist in preschool children with moderate-to-severe intermittent wheezing

BACKGROUND

Acute wheezing illnesses in preschoolers require better management strategies to reduce morbidity.

OBJECTIVES

We sought to examine the effectiveness of episodic use of an inhaled corticosteroid and a leukotriene receptor antagonist in preschoolers with intermittent wheezing.

METHODS

In a randomized, double-blind, placebo-controlled 12-month trial, 238 children aged 12 to 59 months with moderate-to-severe intermittent wheezing received 7 days of either budesonide inhalation suspension (1 mg twice daily), montelukast (4 mg daily), or placebo in addition to albuterol with each identified respiratory tract illness (RTI). Proportion of episode-free days (EFDs) during the 12-month trial was the primary outcome.

RESULTS

The 3 treatment groups did not differ in proportions of EFDs, with adjusted mean EFDs of 76% (95% CI, 70% to 81%) for budesonide, 73% (95% CI, 66% to 79%) for montelukast, and 74% (95% CI, 65% to 81%) for conventional therapy (P = .66). The 3 groups did not differ in oral corticosteroid use, health care use, quality of life, or linear growth. However, during RTIs, budesonide and montelukast therapy led to modest reductions in trouble breathing (38% [P = .003] and 37% [P = .003], respectively) and interference with activity scores (32% [P = .01] and 40% [P = .001], respectively) that were most evident in those with positive asthma predictive indices.

CONCLUSIONS

In preschool children with moderate-to-severe intermittent wheezing, episodic use of either budesonide or montelukast early in RTIs, when added to albuterol, did not increase the proportion of EFDs or decrease oral corticosteroid use over a 12-month period. However, indicators of severity of acute illnesses were reduced, particularly in children with positive asthma predictive indices.

Natural history of asthma: persistence versus progression-does the beginning predict the end?

Environmental exposures during the early years and airway obstruction that develops during this time, in conjunction with genetic susceptibility, are important factors in the development of persistent asthma in childhood. Established risk factors for childhood asthma include frequent wheezing during the first 3 years, a parental history of asthma, a history of eczema, allergic rhinitis, wheezing apart from colds, and peripheral blood eosinophilia, as well as allergic sensitization to aeroallergens and certain foods. Risk factors for the development of asthma in adulthood remain ill defined. Moreover, reasons for variability in the clinical course of asthma--persistence in some individuals and progression in others--remain an enigma. The distinction between disease persistence and disease progression suggests that these are different entities or phenotypes. There is currently no consensus on whether disease progression requires either airway inflammation or airway remodeling or the combination of the two. For patients with irreversible airway obstruction, inflammation might, in part, be necessary but perhaps not entirely sufficient to induce the irreversible component, some of which could be attributed to alterations in the structure of the bronchial wall. Intervening with intermittent or daily inhaled corticosteroids in high-risk infants and children does not prevent disease progression or impaired lung growth. These findings, however, might not apply to adults, and further study in adults is needed to determine the effect of inhaled corticosteroid therapy on disease progression.

Parental language and asthma among urban Hispanic children

BACKGROUND

Many Hispanics in the United States have limited English proficiency and prefer communicating in Spanish. Language barriers are known to adversely affect health care quality and outcomes.

OBJECTIVE

We explored the relationship between parent language preference in a Hispanic population and the likelihood that a child with symptoms receives a diagnosis of asthma.

METHODS

We conducted a school-based survey in 105 Chicago public and Catholic schools. Our sample included 14,177 Hispanic children 6 to 12 years of age with a parent who completed an asthma survey. Outcomes of diagnosed asthma and possible asthma (asthma symptoms without diagnosis) were assessed by using the Brief Pediatric Asthma Screen Plus instrument.

RESULTS

Overall, 12.0% of children had diagnosed asthma, and 12.7% had possible asthma. Parents of children at risk who completed the survey in English reported higher rates of asthma diagnosis compared with parents who completed it in Spanish (55.2% vs 36.3%, P < .001). Predictors of asthma diagnosis were child sex, parental language preference, parental asthma status, and other household members with asthma.

CONCLUSIONS

Parental language preference might be an important characteristic associated with childhood asthma diagnosis. Whether language itself is the key factor or the fact that language is a surrogate for other attributes of acculturation needs to be explored.

CLINICAL IMPLICATIONS

Our findings suggest that estimates of asthma among Hispanic schoolchildren might be low because of underdiagnosis among children whose parents prefer communicating in Spanish.

Prevention of asthma in childhood

PURPOSE OF REVIEW

The prevalence of asthma is increasing in many parts of the world, particularly in developed countries. The present review focuses on recent literature regarding asthma prevention in childhood.

RECENT FINDINGS

Several environmental exposures in infancy or early childhood are associated with reduced prevalence of asthma, but the mechanisms leading to these associations remain unknown. Recent studies have demonstrated limited success in the prevention of asthma or asthma symptoms with the use of asthma medications, once the therapy is discontinued. Immunotherapy offers another strategy for asthma prevention, and groups treated with this intervention have demonstrated reduced atopy and asthma. Several multi-interventional trials have demonstrated a reduced asthma symptom burden but have not demonstrated significant differences in objective measures such as lung function or bronchial hyper-responsiveness between intervention groups.

SUMMARY

The most promising asthma prevention strategies to date have been those that use a multi-interventional approach employing both dietary and environmental manipulations. More research is needed to assess the long-term follow-up of multi-interventional trials and to evaluate novel intervention strategies in the primary or secondary prevention of asthma in childhood.

Effects of treatment with mometasone furoate dry powder inhaler in children with persistent asthma

BACKGROUND

Mometasone furoate dry powder inhaler (DPI) has been shown to effectively treat asthma in children.

OBJECTIVE

To evaluate the efficacy and safety of 2 dosing regimens of mometasone furoate DPI in the treatment of mild-to-moderate persistent asthma in children previously using inhaled corticosteroids (ICSs).

METHODS

A 12-week, multicenter, double-blind, parallel-group, placebo-controlled study evaluated 2 dosing regimens of mometasone furoate DPI (100 microg every evening and 100 microg twice daily) in 296 children 4 to 11 years old with asthma previously using ICSs. The primary efficacy variable was the change in percentage of predicted forced expiratory volume in 1 second (FEV1) from baseline to end point. Secondary efficacy variables included absolute FEV1, forced expiratory flow between 25% and 75% forced vital capacity, morning and evening peak expiratory flow, asthma symptom scores, albuterol use, nocturnal awakenings, response to therapy, and health-related quality of life.

RESULTS

Mean changes from baseline at end point in predicted FEV1 were 4.73 and 5.52 percentage points for mometasone furoate DPI, 100 microg every evening and 100 microg twice daily, respectively, the difference of which was not significant, and -1.77 percentage points for placebo (P < or = .002). Significant improvements in secondary efficacy variables were also observed for both mometasone furoate DPI treatments over placebo. Both mometasone furoate DPI doses were well tolerated, and no significant differences were noted among the 3 treatment groups in adverse event reporting.

CONCLUSIONS

Both mometasone furoate DPI doses were well tolerated and significantly improved lung function, maintained effective asthma control, and improved quality of life in children with asthma.

Forced oscillation technique

FOT may hold the promise of improving the diagnosis of airway obstruction, but may be even better in quantifying the magnitude of airway reversibility and hyper-reactivity, helping in the adjustment of therapy, and monitoring disease progression in young children.

Patterns of asthma-related health care resource use in children treated with montelukast or fluticasone

OBJECTIVE

To examine the impact of controller monotherapy with montelukast or fluticasone on asthma-related health care resource use among children aged 2-14 years old.

DESIGN AND METHODS

A retrospective claims-based analysis of asthmatic children, 2-14 years old, receiving a prescription (index) for montelukast or fluticasone between January 1, 1999 and June 30, 2000 was conducted. Children were matched by age and propensity score to obtain comparable treatment groups. The propensity score was derived using patient demographics, pre-existing respiratory conditions, and asthma-related pharmacy and health service utilization (i.e. ambulatory visits, emergency department visits and hospitalizations). Claims for asthma-related emergent care and medication use were examined for the 12-month periods before and after the index prescription. Treatment group comparisons of asthma-related resource use were conducted for the total pediatric population and separately for children 2-5 years and 6-14 years. Persistent controller medication use was assessed at 6 and 12 months post-index.

RESULTS

A total of 2034 children were matched (1017 in each treatment group). Post-index rates of asthma-related resource use were similar among children treated with montelukast or fluticasone. Among children 2-5 years old, fewer emergency department visits were observed with montelukast versus fluticasone (relative risk = 0.52, 95% confidence interval [CI]: 0.28-0.96); no significant difference was observed among children 6-14 years old. No significant differences between montelukast and fluticasone cohorts in hospitalizations or rescue medication fills were noted in either age group. Evidence of at least one medication refill was significantly greater with montelukast at both 6 and 12 months post-index.

CONCLUSIONS

Similar levels of resource use were achieved by children 2-14 years initiating montelukast or fluticasone, as indicated by use of asthma-related emergent care and rescue/acute medications. Subgroup analyses suggest a differential effect of age on the relationship between treatment and asthma-related resource use, with children 2-5 years observed to have less resource use while on montelukast.

Long-term inhaled corticosteroids in preschool children at high risk for asthma

BACKGROUND

It is unknown whether inhaled corticosteroids can modify the subsequent development of asthma in preschool children at high risk for asthma.

METHODS

We randomly assigned 285 participants two or three years of age with a positive asthma predictive index to treatment with fluticasone propionate (at a dose of 88 mug twice daily) or masked placebo for two years, followed by a one-year period without study medication. The primary outcome was the proportion of episode-free days during the observation year.

RESULTS

During the observation year, no significant differences were seen between the two groups in the proportion of episode-free days, the number of exacerbations, or lung function. During the treatment period, as compared with placebo use, use of the inhaled corticosteroid was associated with a greater proportion of episode-free days (P=0.006) and a lower rate of exacerbations (P<0.001) and of supplementary use of controller medication (P<0.001). In the inhaled-corticosteroid group, as compared with the placebo group, the mean increase in height was 1.1 cm less at 24 months (P<0.001), but by the end of the trial, the height increase was 0.7 cm less (P=0.008). During treatment, the inhaled corticosteroid reduced symptoms and exacerbations but slowed growth, albeit temporarily and not progressively.

CONCLUSIONS

In preschool children at high risk for asthma, two years of inhaled-corticosteroid therapy did not change the development of asthma symptoms or lung function during a third, treatment-free year. These findings do not provide support for a subsequent disease-modifying effect of inhaled corticosteroids after the treatment is discontinued. (ClinicalTrials.gov number, NCT00272441.).

6. Asthma: Factors underlying inception, exacerbation, and disease progression

Asthma is a heterogeneous disorder that is characterized by variable airflow obstruction, airway inflammation and hyperresponsiveness, and reversibility either spontaneously or as a result of treatment. Multiple causes no doubt exist for both its inception and symptom exacerbation once the disease is established. Factors underlying inception can range from viral respiratory tract infections in infancy to occupational exposures in adults. Factors underlying asthma exacerbations include allergen exposure in sensitized individuals, viral infections, exercise, irritants, and ingestion of nonsteroidal anti-inflammatory agents among others. Exacerbating factors might include one or all of these exposures and vary both among and within patients. Asthma treatment is determined to a large extent after an assessment of severity, which can be variable over time and assessed in 2 domains: impairment (current) and risk (long-term consequences). Unfortunately, despite the availability of effective therapies, suboptimal asthma control exists in many patients on a worldwide basis. The future development of novel therapies and treatment paradigms should address these disparities.

Structural and functional localization of airway effects from episodic exposure of infant monkeys to allergen and/or ozone

Both allergen and ozone exposure increase asthma symptoms and airway responsiveness in children. Little is known about how these inhalants may differentially modify airway responsiveness in large proximal as compared to small distal airways. We evaluated whether bronchi and respiratory bronchioles from infant monkeys exposed episodically to allergen and/or ozone differentially develop intrinsic hyperresponsiveness to methacholine and whether eosinophils and/or pulmonary neuroendocrine cells play a role. Infant monkeys were exposed episodically for 5 months to: (1) filtered air, (2) aerosolized house dust mite allergen, (3) ozone 0.5 ppm, or (4) house dust mite allergen + ozone. Studying the function/structure relationship of the same lung slices, we evaluated methacholine airway responsiveness and histology of bronchi and respiratory bronchioles. In bronchi, intrinsic responsiveness was increased by allergen exposure, an effect reduced by bombesin antagonist. In respiratory bronchioles, intrinsic airway responsiveness was increased by allergen + ozone exposure. Eosinophils were increased by allergen and allergen + ozone exposure in bronchi and by allergen exposure in respiratory bronchioles. In both airways, exposure to allergen + ozone resulted in fewer tissue eosinophils than did allergen exposure alone. In bronchi, but not in respiratory bronchioles, the number of eosinophils and neuroendocrine cells correlated with airway responsiveness. We conclude that episodically exposing infant monkeys to house dust mite allergen with or without ozone increased intrinsic airway responsiveness to methacholine in bronchi differently than in respiratory bronchioles. In bronchi, eosinophils and neuroendocrine cells may play a role in the development of airway hyperresponsiveness.

A prospective study of wheezing in young children: the independent effects of cockroach exposure, breast-feeding and allergic sensitization

The objective of this study was to evaluate risk factors for persistent wheezing in a group of 2-4-year-old children after an index-wheezing episode in infancy. Eighty infants who had been seen at the Emergency Department for an episode of acute wheezing were followed for 2 yr in this prospective study. Caregivers completed a questionnaire, and children underwent clinical evaluation and skin prick testing 2 yr following the index-wheezing episode. Detection of respiratory viruses and analysis of exposure to major indoor allergens were carried out at enrollment. Immunoglobin E antibodies were measured at the beginning of the study and at the end of follow-up, using the CAP system. Logistic regression analysis was performed to identify factors associated with persistent wheezing. Seventy-three children (44 boys) completed the study. After 2 yr, 38 (52%) reported three or more wheezing episodes in the past 12 months (persistent wheezers). Independent risk factors for persistence of wheezing were allergic sensitization and exposure to cockroach allergen in the kitchen. Breast-feeding for at least 1 month was a protective factor. A strong association between allergic sensitization and persistence of wheezing was found in a group of very young children living in a subtropical area.

Early intervention of therapy in asthma

PURPOSE OF REVIEW

In addition to the acute manifestations of asthma, researchers now understand that asthma is a chronic inflammatory disease of the airways. Knowing the critical time to intervene in asthma is of utmost importance to clinicians and patients alike. This article reviews recent evidence that early intervention improves long-term outcomes in asthma.

RECENT FINDINGS

The recent published literature demonstrates that early in the course of asthma, changes in structure occur, and that even in very young children, measurable abnormalities of lung function have already occurred. Large studies of inhaled corticosteroids given early in the progression of asthma show, at best, only modest effects on long-term lung function. Though a study on inhaled corticosteroids in very young children is ongoing, there is little evidence to suggest that any other commonly used medications have important effects on underlying lung function. Recent studies have also highlighted the lack of clear understanding of the relation between inflammation and remodeling, and parallel the disappointing results from studies of inhaled corticosteroids on lung function.

SUMMARY

Current anti-inflammatory medications have modest effects on preventing loss of lung function in asthma. Although inhaled corticosteroids are highly efficacious in controlling the overt clinical manifestations of the disease, their effects on lung function are small. The standard paradigm of inflammation leading to remodeling and remodeling to loss of lung function may be overly simplistic. In the future, novel pharmacologic targets and careful timing of treatments must occur to intervene effectively with remodeling and/or decline in lung function in asthma.

Atopic characteristics of children with recurrent wheezing at high risk for the development of childhood asthma

BACKGROUND

Few studies have characterized the atopic profile of toddler-aged children with recurrent wheezing at high risk of the development of persistent asthma. Objective We sought to determine the atopic profile of toddler-aged children with frequent wheeze at high risk for the development of persistent asthma who either had a parental history of asthma, a personal history of atopic dermatitis, or both.

METHODS

Participants enrolled in the Prevention of Early Asthma in Kids study (n = 285) on the basis of a modified Asthma Predictive Index were characterized on the basis of allergy and asthma questionnaire responses and allergy skin puncture test results.

RESULTS

The majority of the children (60.7%, n = 148) were sensitized to either food or aeroallergens. Male children were significantly more likely to be sensitized to aeroallergens ( P = .03) and to have a blood eosinophil level of 4% or greater ( P = .03) and a total serum IgE level of greater than 100 IU/mL ( P = .0004). Additionally, eosinophilia and total serum IgE level had the strongest correlation with aeroallergen sensitization.

CONCLUSION

The high prevalence of aeroallergen sensitization in this high-risk cohort suggests that aeroallergens might have an important role in the early development of asthma. As such, the Prevention of Early Asthma in Kids cohort appears to be an appropriate cohort in which to test whether early intervention with an inhaled corticosteroid can significantly attenuate, or perhaps even prevent, the allergic march from the initial stages of allergic sensitization to the subsequent development of asthma in toddlers with episodic wheezing.