Modeling asthma exacerbations through lung function in children

Pharmacogenetics of inhaled corticosteroids and exacerbation risk in adults with asthma

BACKGROUND

Inhaled corticosteroids (ICS) are a cornerstone of asthma treatment. However, their efficacy is characterized by wide variability in individual responses.

OBJECTIVE

We investigated the association between genetic variants and risk of exacerbations in adults with asthma and how this association is affected by ICS treatment.

METHODS

We investigated the pharmacogenetic effect of 10 single nucleotide polymorphisms (SNPs) selected from the literature, including SNPs previously associated with response to ICS (assessed by change in lung function or exacerbations) and novel asthma risk alleles involved in inflammatory pathways, within all adults with asthma from the Dutch population-based Rotterdam study with replication in the American GERA cohort. The interaction effects of the SNPs with ICS on the incidence of asthma exacerbations were assessed using hurdle models adjusting for age, sex, BMI, smoking and treatment step according to the GINA guidelines. Haplotype analyses were also conducted for the SNPs located on the same chromosome.

RESULTS

rs242941 (CRHR1) homozygotes for the minor allele (A) showed a significant, replicated increased risk for frequent exacerbations (RR = 6.11, P < 0.005). In contrast, rs1134481 T allele within TBXT (chromosome 6, member of a family associated with embryonic lung development) showed better response with ICS. rs37973 G allele (GLCCI1) showed a significantly poorer response on ICS within the discovery cohort, which was also significant but in the opposite direction in the replication cohort.

CONCLUSION

rs242941 in CRHR1 was associated with poor ICS response. Conversely, TBXT variants were associated with improved ICS response. These associations may reveal specific endotypes, potentially allowing prediction of exacerbation risk and ICS response.

Possible Protective Effect of Omalizumab on Lung Function Decline in Patients Experiencing Asthma Exacerbations

BACKGROUND

Frequent exacerbations are associated with greater FEV₁ decline in patients with asthma. The effect of omalizumab versus placebo on lung function in patients experiencing asthma exacerbations has not been previously examined.

OBJECTIVE

To evaluate the relationship between postbaseline (treatment phase) exacerbation status and lung function decline in children, adolescents, and adults treated with omalizumab versus placebo using data from 3 pediatric and adolescent/adult studies.

METHODS

Changes in percent predicted FEV₁ (ppFEV₁) and FEV₁ by treatment (omalizumab/placebo) and postbaseline exacerbation status (exacerbators/nonexacerbators) were assessed in patients aged 6 to 11 years (IA05, n = 576) and 12 to 75 years (EXTRA/INNOVATE pooled, n = 1202). Pediatric patients were examined at treatment weeks 12, 24, 28, 40, and 52, and adolescent/adult data at weeks 4, 12, 20, and 28.

RESULTS

Omalizumab-treated patients experienced larger increases in ppFEV₁ and FEV₁ compared with placebo-treated patients in the pediatric and pooled adolescent/adult populations. The response was observed in pediatric exacerbators, with significantly larger increases in ppFEV₁ and FEV₁ at week 12 (mean difference [95% CI], 4.11% [0.93%-7.30%], P = .011 for ppFEV₁; 80 [10-140] mL, P = .017 for FEV₁) and week 28 (mean difference [95% CI], 3.65% [0.11%-7.19%], P = .043 for ppFEV₁; 100 [30-170] mL, P = .007 for FEV₁). In the adolescent/adult population, both exacerbators and nonexacerbators derived similar benefit with omalizumab compared with placebo.

CONCLUSIONS

Findings from this post hoc analysis suggest that omalizumab may confer some protection against lung function decline among patients who experienced exacerbations during treatment.

Emergency department visit count: a practical tool to predict asthma hospitalization in children

Objectives: Resource limitations and low rates of follow-up with primary care providers currently limit the impact of emergency department (ED)-based preventative strategies for children with asthma. A mechanism to recognize the children at highest risk of future hospitalization is needed to target comprehensive preventative interventions at discharge. The primary objective of this study was to determine whether frequency of ED visits predicts future asthma hospitalization in children.Methods: Children aged 2-16.99 years with asthma ED visits between 2012 and 2015 were identified through health administrative data. Survival analysis using Kaplan-Meier estimator and multivariable Cox regression models with time-varying covariates were used to quantify the number of ED visits in the previous year that would best predict hospitalization risk in the following year, after adjustment for age, sex, and presentation severity.Results: We identified 2669 patients with 3300 asthma ED visits. ED visit count was an independent predictor of future hospitalization risk (p < 0.001), demonstrating a dose-dependent response. Compared with zero previous visits, the adjusted hazard of future hospitalization in children with one visit or two or more visits was 2.9 (95% CI 1.6-5.0) and 4.4 (95% CI 1.9-10.4), respectively.Conclusions: ED visit count is a reliable predictor of future asthma hospitalization risk. Future studies could aim to validate these findings to support using ED visit count as a practical and objective tool to predict the children at the highest risk of future hospitalization and therefore, those who may benefit most from ED-based preventative interventions.

An ensemble learning method for asthma control level detection with leveraging medical knowledge-based classifier and supervised learning

Approximately 300 million people are afflicted with asthma around the world, with the estimated death rate of 250,000 cases, indicating the significance of this disease. If not treated, it can turn into a serious public health problem. The best method to treat asthma is to control it. Physicians recommend continuous monitoring on asthma symptoms and offering treatment preventive plans based on the patient's control level. Therefore, successful detection of the disease control level plays a critical role in presenting treatment plans. In view of this objective, we collected the data of 96 asthma patients within a 9-month period from a specialized hospital for pulmonary diseases in Tehran. A new ensemble learning algorithm with combining physicians' knowledge in the form of a rule-based classifier and supervised learning algorithms is proposed to detect asthma control level in a multivariate dataset with multiclass response variable. The model outcome resulting from the balancing operations and feature selection on data yielded the accuracy of 91.66%. Our proposed model combines medical knowledge with machine learning algorithms to classify asthma control level more accurately. This model can be applied in electronic self-care systems to support the real-time decision and personalized warnings on possible deterioration of asthma control level. Such tools can centralize asthma treatment from the current reactive care models into a preventive approach in which the physician's therapeutic actions would be based on control level.

Efficacy and Safety of Tiotropium in Children and Adolescents

Asthma is one of the most common chronic diseases in children, with a high proportion of patients demonstrating poor control despite the availability of disease management guidelines. Global Initiative for Asthma guidelines include tiotropium as an add-on therapy option at Steps 4 and 5 in patients aged ≥ 12 years with a history of exacerbations, and tiotropium delivered via the Respimat® Soft Mist™ Inhaler has recently been approved for use as once-daily maintenance therapy for children with asthma over the age of 6 years in the USA. A large clinical trial program has been conducted in children, adolescents, and adults across the spectrum of asthma severity. Findings from these clinical studies and pooled analyses in children and adolescents with symptomatic moderate or severe asthma have demonstrated that tiotropium Respimat® as add-on to inhaled corticosteroids, with or without other maintenance therapies, is a well-tolerated and efficacious bronchodilator, showing improved lung function and trends towards improved asthma control, mirroring findings in adult studies. This review discusses the evidence to date for tiotropium Respimat® for the management of asthma in adolescents and children with symptomatic moderate and severe asthma, and considers the challenges of asthma management in these patients. Factors affecting this population group, such as poor adherence, underreporting of symptoms, and social and psychological issues, are highlighted, along with the need for active review and management of treatment to help achieve optimal control.

Personalized management of asthma exacerbations: lessons from genetic studies

INTRODUCTION

The genetics of severe asthma and asthma exacerbations are distinct from milder forms of asthma. Gene-environmental interactions contribute to the complexity and heterogeneity of severe asthma and asthma exacerbations, and pharmacogenomic studies have also identified genes that affect susceptibility to asthma exacerbations.

AREAS COVERED

Studies on the genetics, gene-environment interactions, and pharmacogenomics of asthma exacerbations are reviewed. Multiple individual genetic variants have been identified to be associated with asthma exacerbations but each genetic polymorphism explains only a fraction of the disease and by itself is not able to translate into clinical practice. Research is shifting from candidate gene studies and genome wide association studies towards more integrative approaches to translate genetic findings into clinical diagnostic and therapeutic tools.

EXPERT COMMENTARY

Integrative approaches combining polygenic or genomic data with multi-omics technologies have the potential to discover new biologic mechanisms and biomarkers for severe asthma and asthma exacerbations. Greater understanding of genomics and underlying biologic pathways will also lead to improved prevention and treatment, lowering costs, morbidity, and mortality. The utilization of genomic testing and personalized medicine may revolutionize asthma management, in particular for patients with severe, refractory asthma.

Allergic rhinitis may impact the recovery of pulmonary function tests after moderate/severe asthma exacerbation in children

BACKGROUND

During an asthma exacerbation, pulmonary function test parameters (PFTs) return to their baseline values within a few weeks. Factors affecting the recovery of PFTs other than the severity of exacerbation are not well known.

OBJECTIVE

The primary aim of the study was to determine the risk factors for recovery of PFTs > 7 days after a moderate to severe asthma exacerbation in children.

METHODS

Children who had moderate to severe asthma exacerbation performed serial prebronchodilator PFTs on days 1, 3, 7 of the exacerbation and then once weekly until their PFTs reached a plateau. All children received systemic corticosteroid for 3 days and inhaled salbutamol as long as they needed.

RESULTS

Fifty-seven children were recruited. When all PFTs were considered, 42% and 74% of children recovered within 7 and 14 days, respectively. The last recovered PFT parameter was FEF25-75 . Allergic rhinitis (AR) (P = 0.016), persistent AR (P = 0.005), and severe asthma exacerbation (P = 0.009) were significantly higher in children whose PFTs recover >7 days; only severe asthma exacerbation was different for recovery >14 days (P = 0.048). Logistic regression analysis revealed that AR and severe asthma exacerbation increase the recovery of PFTs > 7 days by 4.3 (95% CI: 1.29-14.67) and 8.1 (95% CI: 1.51-44.43), respectively.

CONCLUSIONS

Recovery of PFTs during a moderate/severe asthma exacerbation may take up to 4 weeks. Apart from severity of the exacerbation, AR is a significant factor affecting the recovery time of PFTs and therefore may impact asthma management. This issue reinforces the combined treatment of AR and asthma.

Physician specialty influences important aspects of pediatric asthma management

BACKGROUND

Physician training influences patient care.

OBJECTIVE

To compare asthma management and change in the percentage predicted FEV1 among pediatric physician specialties.

METHODS

A retrospective cohort of children 6 years of age or older, seen in a multidisciplinary asthma clinic between 2009 and 2010, and followed to 2012, was completed to examine differences in asthma outcomes by specialty (2 pediatricians, 3 pediatric allergists, 5 pediatric respirologists). Univariate analyses compared investigation, including allergy testing (skin prick or RAST), comorbid conditions, and prescription by specialty. Multivariate regression, which controlled for random effect of the individual physician, examined specialty differences for prescribed inhaled corticosteroids (ICS) and changes in percentage predicted FEV1.

RESULTS

More than 56% of the patients (309/548) were seen by pediatric respirologists, 26% by pediatric allergists, and 18% by pediatricians. Physician specialty influences investigation requested, comorbid diagnoses, treatment, and improvement in FEV1. Pediatric allergists' patients had more allergy tests, were more likely to be diagnosed with allergic rhinitis and, consequently, were more likely to be prescribed nasal steroids than pediatricians and pediatric respirologists. Pediatricians were less likely to prescribe ICS (odds ratio 0.39 [95% CI, 0.15-0.96]; P < .05) than pediatric allergists, with the greatest difference in ICS prescription among children with a percentage predicted FEV1 ≥ 80%. Improvement in FEV1 among children who received care with pediatric allergists was higher than those seen by pediatricians (13%; P < .001) and pediatric respirologists (8%; P = .005).

CONCLUSIONS

Patient management domains with the greatest room for discretion (investigations, comorbid diagnoses, and treatment with ICS among children with normal lung function) are most heavily influenced by physician specialty. These results have implications for asthma management at the patient level and in future practice guidelines.

Asthma exacerbations: predisposing factors and prediction rules

PURPOSE OF REVIEW

Asthma is a multifaceted disease that is associated with decreased lung function, multiple symptoms, varying levels of asthma control, and risk of acute exacerbations. The ability to predict the risk of developing acute exacerbations may improve the management of asthmatics and facilitate identification of these patients for interventional studies.

RECENT FINDINGS

Factors that are associated with different manifestations of asthma differ. Biomarkers that are correlated with airways hyper-responsiveness do not necessarily correlate with risk of future exacerbations. Genetic factors that segregate with exacerbation risk are beginning to emerge. Outcome measures that demonstrate predictive validity have been developed and may facilitate patient management and provide novel clinically meaningful endpoints in clinical trials.

SUMMARY

This review will emphasize underlying factors associated with asthma exacerbations and clinical prediction rules that correlate with the risk of developing severe exacerbations of asthma.

The relationship between a specific IgE level and asthma outcomes: results from the 2005-2006 National Health and Nutrition Examination Survey

BACKGROUND

Allergen exposure is associated with increased specific IgE (sIgE), and allergen exposure plus sensitization is predictive of asthma outcomes. However, it is not known if sIgE is predictive of asthma outcomes in the absence of exposure data.

OBJECTIVE

To investigate whether IgE to indoor allergens is predictive of and has a dose-response relationship with asthma emergency department (ED) visits and wheeze.

METHODS

In the 2005-2006 National Health and Nutrition Examination Survey, 351 children and 390 adults reported current asthma. Continuous sIgE to 9 indoor allergens were considered. Asthma morbidity in the past year was measured by wheezing. Health care utilization was defined as any asthma ED visits in the past year.

RESULTS

Analyses were adjusted for race, age, education, poverty index ratio and (in adults) tobacco use. In children, ED visits were associated with cockroach (odds ratio [OR] 1.5 [95% CI, 1.1-2 .1), rat (OR 1.9 [95% CI, 1.2-2.8]), and Aspergillus (OR 1.6 [95% CI, 1.001-2.60]). Continuous Aspergillus (OR 1.5 [95% CI, 1.04-2.1), Alternaria (OR 1.4 [95% CI, 1.1-1.6]), and total IgE (OR 1.2 [95% CI, 1.1-1.4]) were associated with wheeze in children. Adult ED visits were associated with sIgE for dust mites (Dermatophagoides pteronyssinus OR 1.6 [95% CI, 1.3-2.1]; Dermatophagoides farinae OR 1.6 [95% CI, 1.3-1.9]), total IgE (OR 1.4 [95% CI, 1.04- 1.9]), and the sum of sIgEs (OR 1.6 [95% CI, 1.2-2.2]).

CONCLUSIONS

Sensitization to particular indoor environmental allergens was found to be a risk factor for wheeze and asthma ED visits. These outcomes increased as the concentration of sIgE to these allergens increased.

Advances in pediatric asthma in 2012: moving toward asthma prevention

Last year's "Advances in pediatric asthma: moving forward" concluded the following: "Now is also the time to utilize information recorded in electronic medical records to develop innovative disease management plans that will track asthma over time and enable timely decisions on interventions in order to maintain control that can lead to disease remission and prevention." This year's summary will focus on recent advances in pediatric asthma on modifying disease activity, preventing asthma exacerbations, managing severe asthma, and risk factors for predicting and managing early asthma, as indicated in Journal of Allergy and Clinical Immunology publications in 2012. Recent reports continue to shed light on methods to improve asthma management through steps to assess disease activity, tools to standardize outcome measures in asthma, genetic markers that predict risk for asthma and appropriate treatment, and interventions that alter the early presentation of asthma to prevent progression. We are well on our way to creating a pathway around wellness in asthma care and also to use new tools to predict the risk for asthma and take steps to not only prevent asthma exacerbations but also to prevent the early manifestations of the disease and thus prevent its evolution to severe asthma.