Questions in Mild Asthma: An Official American Thoracic Society Research Statement

Background: Patients with mild asthma are believed to represent the majority of patients with asthma. Disease-associated risks such as exacerbations, lung function decline, and death have been understudied in this patient population. There have been no prior efforts from major societies to describe research needs in mild asthma. Methods: A multidisciplinary, diverse group of 24 international experts reviewed the literature, identified knowledge gaps, and provided research recommendations relating to mild asthma definition, pathophysiology, and management across all age groups. Research needs were also investigated from a patient perspective, generated in conjunction with patients with asthma, caregivers, and stakeholders. Of note, this project is not a systematic review of the evidence and is not a clinical practice guideline. Results: There are multiple unmet needs in research on mild asthma driven by large knowledge gaps in all areas. Specifically, there is an immediate need for a robust mild asthma definition and an improved understanding of its pathophysiology and management strategies across all age groups. Future research must factor in patient perspectives. Conclusions: Despite significant advances in severe asthma, there remain innumerable research areas requiring urgent attention in mild asthma. An important first step is to determine a better definition that will accurately reflect the heterogeneity and risks noted in this group. This research statement highlights the topics of research that are of the highest priority. Furthermore, it firmly advocates the need for engagement with patient groups and for more support for research in this field.

554 Utilization of Pediatric Sleep Questionnaire to Screen for Obstructive Sleep Apnea in a Difficult-to-treat Asthma Cohort

Introduction

Early detection and management of obstructive sleep apnea(OSA) could improve asthma control in children with difficult-to-treat(DTT) asthma. The purpose of this study was to assess the effectiveness of the pediatric sleep questionnaire(PSQ) to screen for OSA in children with DTT asthma, and to compare clinical characteristics between those with positive and negative PSQ scores.

Methods

A prospective study of 81 children with DTT asthma was completed from 2015–2017. The PSQ, Epworth sleepiness scale(ESS), Pediatric Quality of Life(PQL), and the academic performance questionnaires(APQ) were administered during clinic visits. Polysomnography(PSG) was recommended for PSQ score>0.33. Medical records were reviewed for asthma clinical characteristics. The cohort was separated into positive(PSQ>0.33) and negative PSQ score(PSQ≤0.33) groups for analysis.

Results

The mean age of the cohort was 11.3±4.5 years and the mean body mass index was 22±7.6 kg/m2. Sixty-two percent were male and 68% were African-American. Forty-nine(53%) subjects had positive PSQ (0.5[0.4 – 0.7]). The positive group had higher ESS score (10.5[8 – 13] vs. 6[2 – 8], p<0.0001) and lower total PQL score (58.7[47.8–72.8] vs. 79.4[70.7 – 87], p<0.0001) than the negative group. There was no difference between APQ scores(p=0.07). The positive group had lower asthma control test(ACT) scores than the negative group (17.5[15 – 20.5] vs. 21[19 – 22], p<0.0001). Furthermore, the positive group was more likely to have gastroesophageal reflux (OR: 3.97, 95%CI: 1.7 to 9.1, p=0.0018). Twenty-nine(59%) subjects in the positive group had subsequent PSG, and 17(58.6%) subjects were diagnosed with OSA (14 mild OSA, 1 moderate OSA, 2 severe OSA). The mean obstructive index in the positive group was 3±5.5 events/hour. There was 1 subject with central apnea and alveolar hypoventilation. Of the 17 subjects with OSA, all received treatment with nasal steroids, 3 were treated with non-invasive positive pressure ventilation, and 4 had surgical intervention.

Conclusion

Children with DTT asthma who have positive PSQ have higher degree of daytime sleepiness, lower quality of life and worse asthma control. The positive group was more likely to have GERD, which may suggest a relationship between nighttime asthma symptoms and OSA. Further studies are needed to evaluate the effects of OSA treatment on asthma control.

Support (if any):

Modeling Asthma Exacerbations from Electronic Health Records

Asthma is a prevalent chronic respiratory condition, and acute exacerbations represent a significant fraction of the economic and health-related costs associated with asthma. We present results from a novel study that is focused on modeling asthma exacerbations from data contained in patients' electronic health records. This work makes the following contributions: (i) we develop an algorithm for phenotyping asthma exacerbations from EHRs, (ii) we determine that models learned via supervised learning approaches can predict asthma exacerbations in the near future (AUC ≈ 0.77), and (iii) we develop an approach, based on mixtures of semi-Markov models, that is able to identify subpopula-tions of asthma patients sharing distinct temporal and seasonal patterns in their exacerbation susceptibility.

Heterogeneity of Mild to Moderate Persistent Asthma in Children: Confirmation by Latent Class Analysis and Association with 1-Year Outcomes

BACKGROUND

Compared with adults, phenotypic characterization of children with asthma is still limited and it remains difficult to predict which children with asthma are at highest risk for poor outcomes.

OBJECTIVE

To identify latent classes in a large population of treatment-adherent children with mild to moderate asthma enrolled in clinical trials and determine whether latent class assignment predicts future lung function abnormalities and exacerbation rate.

METHODS

Latent class analysis was performed on 2593 children with mild to moderate asthma aged 5 18 years, with 19 variables encompassing demographic characteristics, medical history, symptoms, lung function, allergic sensitization, and type 2 inflammation. Outcomes included lung function and the annualized exacerbation rate at 12 months of follow-up.

RESULTS

Five latent classes were identified with differing demographic features, asthma control, sensitization, type 2 inflammatory markers, and lung function. Exacerbation rates were 1.30 ± 0.12 for class 1 (multiple sensitization with partially reversible airflow limitation), 0.90 ± 0.05 for class 2 (multiple sensitization with reversible airflow limitation), 0.87 ± 0.08 for class 3 (lesser sensitization with reversible airflow limitation), 0.87 ± 0.05 for class 4 (multiple sensitization with normal lung function), and 0.71 ± 0.06 for class 5 (lesser sensitization with normal lung function). Lung function abnormalities persisted in class 1 at 12 months.

CONCLUSIONS

Children with mild to moderate asthma are a heterogeneous group. Allergic sensitization and lung function may be particularly useful in identifying children at the greatest risk for future exacerbation. Additional studies are needed to determine whether latent classes correspond to meaningful phenotypes for the purpose of personalized treatment.

Racial Disparities in Asthma-Related Health Outcomes in Children with Severe/Difficult-to-Treat Asthma

BACKGROUND

There are limited data that examine differences in asthma etiology between black and white children with severe or difficult-to-treat asthma.

OBJECTIVE

To describe demographic, clinical, and asthma-related outcomes in black and white children and examine whether differences in outcomes are explained by confounding factors in sequential multivariable models.

METHODS

Black (n = 86) and white (n = 262) children aged 6-11 years from The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens 3-year observational study were analyzed. Baseline demographics and clinical characteristics were described for both cohorts, and outcomes at month 12 were analyzed using statistical models, sequentially adjusting for potential confounders.

RESULTS

Black children were more likely to be male (79.1% vs 66.4%; P < .05), obese (12.8% vs 1.5%; P < .001), and from a lower income stratum (USD43,400 vs 55,770; P < .001) than white children. Black children had higher geometric mean IgE levels (434.8 vs 136.8 IU/mL; P < .001), were more likely to have very poorly controlled asthma (72.1% vs 53.4%), use long-term systemic corticosteroids (30.2% vs 9.2%; P < .001), have poorer quality of life (5.5 vs 6.1; P < .001), and have an emergency department visit (27.4% vs 7.7%, P < .001) in the 3 months before month 12. Differences in asthma control and the severity of exacerbations persisted even after accounting for all confounding factors.

CONCLUSIONS

Among children with severe or difficult-to-treat asthma, asthma burden is greater in black than white children particularly related to several clinical and patient-reported outcome measures that are not explained by differences in background or clinical characteristics.

Extrafine Versus Fine Inhaled Corticosteroids in Relation to Asthma Control: A Systematic Review and Meta-Analysis of Observational Real-Life Studies

BACKGROUND

The particle size of inhaled corticosteroids (ICSs) may affect airway drug deposition and effectiveness.

OBJECTIVE

To compare the effectiveness of extrafine ICSs (mass median aerodynamic diameter, <2 μm) versus fine-particle ICSs administered as ICS monotherapy or ICS-long-acting β-agonist combination therapy by conducting a meta-analysis of observational real-life asthma studies to estimate the treatment effect of extrafine ICSs.

METHODS

MEDLINE and EMBASE databases were reviewed for asthma observational comparative effectiveness studies from January 2004 to June 2016. Studies were included if they reported odds and relative risk ratios and met all inclusion criteria (Respiratory Effectiveness Group/European Academy of Allergy and Clinical Immunology quality standards, comparison of extrafine ICSs with same or different ICS molecule, ≥12-month follow-up). End-point data (asthma control, exacerbations, prescribed ICS dose) were pooled. Random-effects meta-analysis modeling was used. The study protocol is published in the PROSPERO register CRD42016039137.

RESULTS

Seven studies with 33,453 subjects aged 5 to 80 years met eligibility criteria for inclusion. Six studies used extrafine beclometasone propionate and 1 study used both extrafine beclometasone propionate and extrafine ciclesonide as comparators with fine-particle ICSs. The overall odds of achieving asthma control were significantly higher for extrafine ICSs compared with fine-particle ICSs (odds ratio, 1.34; 95% CI, 1.22-1.46). Overall exacerbation rate ratios (0.84; 95% CI, 0.73-0.97) and ICS dose (weighted mean difference, -170 μg; 95% CI, -222 to -118 μg) were significantly lower for extrafine ICSs compared with fine-particle ICSs.

CONCLUSIONS

This meta-analysis demonstrates that extrafine ICSs have significantly higher odds of achieving asthma control with lower exacerbation rates at significantly lower prescribed doses than fine-particle ICSs.

Effectiveness of initiating extrafine-particle versus fine-particle inhaled corticosteroids as asthma therapy in the Netherlands

Background

Most randomised clinical trials typically exclude a significant proportion of asthma patients, including those at higher risk of adverse events, with comorbidities, obesity, poor inhaler technique and adherence, or smokers. However, these patients might differentially benefit from extrafine-particle inhaled corticosteroids (ICS). This matched cohort, database study, compared the effectiveness of extrafine-particle with fine-particle ICS in a real-life population initiating ICS therapy in the Netherlands.

Methods

Data were from the Pharmo Database Network, comprising pharmacy and hospital discharge records, representative of 20 % of the Dutch population. The study population included patients aged 12 − 60, with a General Practice-recorded diagnosis for asthma (International Classification of Primary Care code R96), when available, ≥2 prescriptions for asthma therapy at any time in their recorded history, and receiving first prescription of ICS therapy as either extrafine-particle (ciclesonide or hydrofluoroalkane beclomethasone dipropionate [BDP]) or fine-particle ICS (fluticasone propionate or non-extrafine-particle-BDP). Patients were matched (1:1) on relevant demographic and clinical characteristics over 1-year baseline. Primary outcomes were severe exacerbation rates, risk domain asthma control and overall asthma control during the year following first ICS prescription. Secondary outcomes, treatment stability and being prescribed higher versus lower category of short-acting β2 agonists (SABA) dose, were compared over a 1-year outcome period using conditional logistic regression models.

Results

Following matching, 1399 patients were selected in each treatment cohort (median age: 43 years; males: 34 %). Median (interquartile range) initial ICS doses (fluticasone-equivalents in μg) were 160 (160 − 320) for extrafine-particle versus 500 (250 − 500) for fine-particle ICS (p < 0.001). Following adjustment for residual confounders, matched patients prescribed extrafine-particle ICS had significantly lower rates of exacerbations (adjusted rate ratio [95 % CI], 0.59 [0.47–0.73]), and significantly higher odds of achieving asthma control and treatment stability in the year following initiation than those prescribed fine-particle ICS, and this occurred at lower prescribed doses. Patients prescribed extrafine-particle ICS had lower odds of being prescribed higher doses of SABA (0.50 [0.44–0.57]).

Conclusion

In this historical, matched study, extrafine-particle ICS was associated with better odds of asthma control than fine-particle ICS in patients prescribed their first ICS therapy in the Netherlands. Of importance, this was reached at significantly lower prescribed dose.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0234-0) contains supplementary material, which is available to authorized users.

How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration

Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development.

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.

Severe intermittent wheezing in preschool children: a distinct phenotype

BACKGROUND

Young children with wheezing predominantly with respiratory tract illnesses experience severe exacerbations separated by extended periods of wellness and may be described as having "severe intermittent wheezing," a diagnostic category not currently recognized in national guidelines.

OBJECTIVE

We sought to characterize a cohort of children with recurrent severe wheezing.

METHODS

A total of 238 children 12 to 59 months enrolled in the Acute Intervention Management Strategies trial were characterized through comprehensive allergy, asthma, environmental, and quality of life assessments.

RESULTS

Asthma symptoms over the period of the preceding year occurred at frequencies consistent with intermittent asthma, as 94.5% of children experienced activity limitation < or = 2 times per month. However, frequent severe exacerbations were common, because 71% experienced > or = 4 wheezing episodes over the period of the preceding year, 95% made at least 1 primary care visit, 52% missed school or daycare, 40% made an emergency department visit, and 8% were hospitalized for wheezing illnesses. Atopic features were common, including eczema (37%), aeroallergen sensitization (46.8%), and positive asthma predictive index (59.7%). Oral corticosteroid use in the previous year (59.7% of the cohort) identified a subgroup with more severe disease documented by a higher incidence of urgent care visits (P = .0048), hospitalizations (P = .0061), aeroallergen sensitization (P = .047), and positive asthma predictive indices (P = .007).

CONCLUSION

Among preschool children enrolled in the Acute Intervention Management Strategies trial, a subgroup was identified with severe intermittent wheezing characterized by atopic features and substantial illness-related symptom burden despite prolonged periods of wellness.

CLINICAL IMPLICATIONS

Preschool children with recurrent severe wheezing episodes experience significant illness-related morbidity and exhibit features of atopic predisposition.

The influence of variation in type and pattern of symptoms on assessment in pediatric asthma

OBJECTIVE

We conducted a national, population-based survey to examine the asthma-related health burden of US children.

METHODS

A telephone-based survey was conducted in 2004 of children 4 to 18 years of age with current asthma in the United States. In 41,433 households screened, 1089 children reported current asthma; 801 interviews were completed by parents of children aged 4 to 15 years and by children themselves aged 16 to 18 years. The survey included questions about symptoms, perceived level of control, activity limitations, health care use, medicines, disease management, and knowledge. Global asthma symptom burden, derived from the National Asthma Education and Prevention Program guidelines, was composed of 3 components: short-term symptom burden (4-week recall), long-term symptom burden (past year), and functional impact (activity limitation).

RESULTS

The majority of children were classified with mild intermittent disease on the basis of recent daytime symptoms alone (80%); yet, when report of nighttime symptoms was included, the proportion of children classified as having mild intermittent symptoms decreased (74%). When asthma burden was assessed on the basis of the global symptom burden construct, only a minority (13%) of individuals was classified as having an asthma symptom burden consistent with mild intermittent disease; the majority (62%) was classified as having moderate/severe disease. In addition, the impact of asthma on the daily activities is substantial; avoiding exertion (47%) and staying inside (34%) are common approaches to improve control of asthma symptoms.

CONCLUSIONS

The goals of therapy for asthma, based on the National Asthma Education and Prevention Program guidelines, have not been achieved for the majority of children. In addition, parents and children overestimate the child's asthma control and commonly restrict activities to control asthma symptoms. Deficiencies in the control of asthma may be related to the underestimation of the burden of disease.

Assessing respiratory function in young children: Developmental considerations

The purpose of this review is to provide practitioners and clinical investigators with an update on methods of assessing respiratory function in young children. The importance of this topic is presented in light of the natural history of asthma, as well as maturational changes that occur early in life in terms of airway development. Models of disease are cited to support the concept that injury of the mammalian airway early in postnatal life might have far-reaching consequences in terms of control of airway caliber and responsiveness. The methods currently available to measure respiratory function in our younger patients are outlined. The ability of children to perform the maneuvers necessary for this testing is considered as a function of age. Areas in which research and development are needed are highlighted.

Natural history of asthma

For some children, asthma is a disease whose symptoms seem to remit with time. Numerous children, however, develop disease that is persistent throughout their lifetimes and is associated with more severe symptoms, increased airway reactivity, and loss of lung function. These children typically have a family history of asthma and demonstrate increased airways reactivity and atopy in childhood. A clearer picture of the natural history of asthma in the developing child has been derived from the results of several longitudinal studies. Although some questions have been clarified, several questions still remain. Now that the incidence and severity of asthma seem to be increasing, children born in the last 10 years may experience more severe disease or a different pathophysiology than those born 30 to 40 years ago. New cohort studies are needed to assess this possibility. Additional investigations into the genetics of asthma causation will help elucidate the different phenotypic expressions of this complex disease. Once these different phenotypic groups can be identified early in life, further studies can be performed to explore the impact of therapeutic intervention on the severity of asthma symptoms and loss of lung function.

Inadequate use of asthma medication in the United States: results of the asthma in America national population survey

BACKGROUND

Studies of the use of anti-inflammatory asthma therapy have been limited to selected populations or have been unable to assess the appropriateness of therapy for individuals.

OBJECTIVE

We sought to describe the current use of asthma medication in the United States population and to examine the influence of symptoms and sociodemographics on medication use.

METHODS

This study was based on a cross-sectional, national, random-digit-dial household telephone survey in 1998 designed to identify adult patients and parents of children with current asthma. Respondents were classified as having current asthma if they had a physician's diagnosis of asthma and were either taking medication for asthma or had asthma symptoms during the past year.

RESULTS

One or more persons met the study criteria for current asthma in 3273 (7.8%) households in which a screening questionnaire was completed. Of these, 2509 persons (721 children <16 years) with current asthma were interviewed. Current use of anti-inflammatory medication was reported by 507 (20.1%). Of these, most were using inhaled corticosteroids (72.5%), with use of antileukotrienes reported by 11.4% and use of cromolyn-nedocromil reported by 18.6%. Of persons with persistent asthma symptoms in the past month, 26.2% reported current use of some form of anti-inflammatory medication. In bivariate analysis persons reporting lower income, less education, and present unemployment, as well as smokers, were significantly (P <.001) less likely to report current anti-inflammatory use than were other populations. In a multiple regression model nonsmokers and those of white, non-Hispanic ethnicity, as well as persons reporting less asthma control, were more likely to report current anti-inflammatory medication use.

CONCLUSION

In the United States use of appropriate asthma therapy remains inadequate. Strategies to increase use of anti-inflammatory therapy among patients with asthma are needed. These might include methods to increase access to asthma care for minorities and the socioeconomically disadvantaged.