Demographic and clinical characteristics of children and adolescents with severe or difficult-to-treat asthma

The molecular phenotype of severe asthma in children

BACKGROUND

Although the clinical attributes of severe asthma in children have been well described, the differentiating features of the lower airway inflammatory response are less understood.

OBJECTIVES

We sought to discriminate severe from moderate asthma in children by applying linear discriminant analysis, a supervised method of high-dimensional data reduction, to cytokines and chemokines measured in the bronchoalveolar lavage (BAL) fluid and alveolar macrophage (AM) lysate.

METHODS

Bronchoalveolar lavage fluid was available from 53 children with asthma (severe asthma, n = 31) undergoing bronchoscopy for clinical indications and 30 nonsmoking adults. Twenty-three cytokines and chemokines were measured by using bead-based multiplex assays. Linear discriminant analyses of the BAL fluid and AM analytes were performed to develop predictive models of severe asthma in children.

RESULTS

Although univariate analysis of single analytes did not differentiate severe from moderate asthma in children, linear discriminant analyses allowed for near complete separation of the moderate and severe asthmatic groups. Significant correlations were also noted between several of the AM and BAL analytes measured. In the BAL fluid, IL-13 and IL-6 differentiated subjects with asthma from controls, whereas growth-related oncogene (CXCL1), RANTES (CCL5), IL-12, IFN-gamma, and IL-10 best characterized severe versus moderate asthma in children. In the AM lysate, IL-6 was the strongest discriminator of all the groups.

CONCLUSION

Severe asthma in children is characterized by a distinct airway molecular phenotype that does not have a clear T(H)1 or T(H)2 pattern. Improved classification of children with severe asthma may assist with the development of targeted therapeutics for this group of children who are difficult to treat.

Omalizumab for the treatment of exacerbations in children with inadequately controlled allergic (IgE-mediated) asthma

BACKGROUND

Many children with asthma continue to experience symptoms despite available therapies.

OBJECTIVE

This study evaluated the efficacy and safety of omalizumab, a humanized anti-IgE mAb, in children with moderate-to-severe persistent allergic (IgE-mediated) asthma that was inadequately controlled despite treatment with medium-dose or high-dose inhaled corticosteroids (ICSs) with or without other controller medications.

METHODS

A randomized, double-blind, placebo-controlled trial enrolled children age 6 to <12 years with perennial allergen sensitivity and history of exacerbations and asthma symptoms despite at least medium-dose ICSs. Patients were randomized 2:1 to receive omalizumab (75-375 mg sc, q2 or q4 wk) or placebo over a period of 52 weeks (24-week fixed-steroid phase followed by a 28-week adjustable-steroid phase).

RESULTS

A total of 627 patients (omalizumab, n = 421; placebo, n = 206) were randomized, with efficacy analyzed in 576 (omalizumab, n = 384; placebo, n = 192). Over the 24-week fixed-steroid phase, omalizumab reduced the rate of clinically significant asthma exacerbations (worsening symptoms requiring doubling of baseline ICS dose and/or systemic steroids) by 31% versus placebo (0.45 vs 0.64; rate ratio, 0.69; P = .007). Over a period of 52 weeks, the exacerbation rate was reduced by 43% versus placebo (P < .001). Omalizumab significantly reduced severe exacerbations. Over a period of 52 weeks, omalizumab had an acceptable safety profile, with no difference in overall incidence of adverse events compared with placebo.

CONCLUSION

Add-on omalizumab is effective and well tolerated as maintenance therapy in children (6 to <12 years) with moderate-to-severe persistent allergic (IgE-mediated) asthma whose symptoms are inadequately controlled despite medium to high doses of ICSs.

The irreversible component of persistent asthma

Irreversible airflow obstruction or limitation occurs in some patients with asthma, can develop early in life, and becomes more common as asthma becomes more severe. Efforts to understand irreversible airflow obstruction or limitation have been hampered by the lack of a standardized definition of the phenotype and by the lack of appropriate research models. Unfortunately, it appears that currently available asthma treatments do not prevent this important asthma complication. Herein, the evidence of an irreversible component of asthma, its underlying pathology, and the limitations of current asthma treatments are reviewed.

[Diagnosis and treatment guidelines for difficult-to-control asthma in children]

Children suffering from difficult-to-control asthma (DCA) require frequent appointments with their physician, complex treatment regimes and often admissions to hospital. Less than 5% of the asthmatic population suffer this condition. DCA must be correctly characterised to rule out false causes of DCA and requires making a differential diagnosis from pathologies that mimic asthma, comorbidity, environmental and psychological factors, and analysing the factors to determine poor treatment compliance. In true DCA cases, inflammation studies (exhaled nitric oxide, induced sputum, broncho-alveolar lavage and bronchial biopsy), pulmonary function and other clinical aspects can classify DCA into different phenotypes which could make therapeutic decision-making easier.

Consistently very poorly controlled asthma, as defined by the impairment domain of the Expert Panel Report 3 guidelines, increases risk for future severe asthma exacerbations in The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens (TENOR) study

BACKGROUND

Identification of patients at risk for asthma exacerbations can assist physicians in addressing disease management and improve asthma-related health outcomes.

OBJECTIVE

We sought to evaluate whether level of impairment, as defined by the 2007 asthma guidelines, predicts risk for future asthma exacerbations.

METHODS

The study included children aged 6 to 11 years (n = 82) and adolescent/adult patients aged 12 years and older (n = 725) from The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens study with data representing all components of the impairment domain of the asthma guidelines at baseline, month 12, and month 24. Patients were categorized into 2 cohorts: (1) consistently very poorly controlled (VPC) asthma from baseline through 2 years of follow-up and (2) improved from VPC asthma at baseline (including patients who improved to not well-controlled or well-controlled asthma), with improvement maintained through 2 years of follow-up. Odds ratios (ORs) and 95% CIs for risk of asthma exacerbations at month 30 were generated by using multivariable logistic regression by age group.

RESULTS

After adjustment, children with consistently VPC asthma over the 2-year period demonstrated a 6-fold increased risk of hospitalization, emergency department visit, or corticosteroid burst (OR, 6.4; 95% CI, 1.2-34.5) compared with the improved group. Adolescent/adult patients with consistently VPC asthma were more likely to have a corticosteroid burst (OR, 2.8; 95% CI, 1.7-4.8) or have a hospitalization, emergency department visit, or corticosteroid burst (OR, 3.2; 95% CI, 1.9-5.3).

CONCLUSIONS

Consistently VPC asthma, as defined by the impairment domain of the 2007 asthma guidelines, is strongly predictive of future asthma exacerbations.

Adding omalizumab to the therapy of adolescents with persistent uncontrolled moderate--severe allergic asthma

OBJECTIVE

This study aimed to evaluate the effectiveness of omalizumab among adolescents with moderate-severe allergic asthma inadequately controlled with inhaled corticosteroids.

PATIENTS AND METHODS

Data from patients 12 to 17 years of age were pooled from 5 placebo-controlled registration trials of omalizumab. Impact on asthma control was assessed by need for rescue bursts of oral corticosteroids, lung function, symptom scores, and unscheduled office visits.

RESULTS

In adolescents (n = 146), addition of omalizumab decreased mean number of rescue bursts (0.3 vs 0.9) versus placebo; relative risk 0.47 (95% confidence interval [CI], 0.22-0.99; P = .047). At study conclusion, mean forced expiratory volume in 1 second increased 268 mL (13.8%) in omalizumab-treated subjects versus 98 mL (5.5%) for placebo (least squares mean treatment difference 146 mL [95% CI, 19.4-272.6; P = .024]). Omalizumab significantly improved asthma symptom scores and reduced unscheduled office visits.

CONCLUSION

Omalizumab added to baseline therapy improves measures of asthma control in adolescents with persistent moderate-severe allergic asthma.

Omalizumab in the management of patients with allergic (IgE-mediated) asthma

Immunoglobulin E (IgE) is central to the pathophysiology of allergic asthma. Omalizumab, an anti-IgE monoclonal antibody, binds to the FcɛRI binding site on free IgE. As a result, circulating free IgE is reduced, IgE is prevented from attaching to mast cells and basophils, and FcɛRI receptor expression is down-regulated. The inflammatory response to allergens and the acute and chronic effector phases of allergic inflammation are thereby attenuated. In clinical trials in adults and adolescents, omalizumab reduced asthma exacerbations, severe asthma exacerbations, inhaled corticosteroid requirements, and emergency visits, as well as significantly improving asthma-related quality of life, morning peak expiratory flow and asthma symptom scores in patients with severe allergic (IgE-mediated) asthma. Results from clinical trials in children (<12 years) are consistent with those in the adult population. It is difficult to predict which patients will respond to omalizumab. Responders to omalizumab should be identified after a 16-week trial of therapy using the physician's overall assessment. When treatment is targeted to these responders, omalizumab provides a cost-effective therapy for inadequately controlled severe allergic (IgE-mediated) asthma. Long-term therapy with omalizumab shows the potential for disease-modification in asthma. Ongoing studies are also evaluating the use of omalizumab in other non-asthma IgE-mediated conditions.

Severe asthma in childhood: assessed in 10 year olds in a birth cohort study

BACKGROUND

Limited information is available regarding the prevalence of severe asthma in children. The present study aimed at investigating the prevalence of severe asthma in an urban child population; secondarily evaluating the applicability of the chosen definition by clinical characteristics.

METHODS

Children enrolled in the prospective birth cohort; the Environment and Childhood Asthma Study in Oslo; were reinvestigated at the age of 10 years (n = 1019). A representative population based cohort of 616 children [mean age 10.9 (SD 0.9) years] with lung function measurements at birth was used for prevalence estimates, whereas all 1019 children (154 with current asthma) attending the 10-year follow-up were included for verification of the definition of severe asthma. Clinical investigations included spirometry, tests of bronchial hyperresponsiveness, skin prick tests and exhaled nitric oxide. Severe asthma was defined as poorly controlled asthma despite treatment with > or = 800 microg budesonide or equivalent; assessed by a detailed structured interview.

RESULTS

The population point prevalence at age 10 years of current severe asthma was 0.5% (three of 616) and among children with current asthma 4.5% (three of 67). The 10/154 children identified as suffering from severe asthma more often had severe bronchial hyperresponsiveness (PD(20) methacholine <1 micromol) (60%vs 22%, P = 0.015), lower median forced expiratory volume in 1 s/forced vital capacity ratio (93%vs 99%, P = 0.04) and higher body mass index (mean BMI 22.3 vs 18.3, P < 0.001) than nonsevere current asthmatics.

CONCLUSIONS

The prevalence of severe asthma was 0.5% in all 10-year olds, and 4.5% among current asthmatics. The severe asthma definition applied in this study is supported by results of clinical investigations.

Advances in the care of adults with asthma and allergy in 2007

In 2007 the National Asthma Education and Prevention Program published the Expert Panel Report 3, updating its 1997 and 2002 guidelines for the diagnosis and management of asthma with new emphasis on assessment and attainment of control. This review focuses on the Journal articles published in 2007 pertaining to risk and impairment in adult asthma and interventions to improve its control.

Advances in pediatric asthma in 2007

This year's summary focuses on recent advances in pediatric asthma as reported in 2007 publications in the Journal. This past year, new National Asthma Education and Prevention Program asthma guidelines were released with a special emphasis on new information in pediatric asthma. Journal theme issues in 2007 included the revised National Asthma Education and Prevention Program asthma guidelines, the accomplishments of the National Institutes of Health asthma networks, and focused discussions on environmental allergens, neutrophils, eosinophils, T cells, and epithelial cells, all of which affect pediatric asthma. The new asthma guidelines emphasize several key terms including severity, control, impairment, risk, and responsiveness that are relevant for advancing the care of children with asthma. This review highlights journal articles that relate to these guideline topics.