'We can't diagnose asthma until <insert arbitrary age>'

Bacteria and viruses and their role in the preschool wheeze to asthma transition

Wheezing is the cardinal symptom of asthma; its presence early in life, mostly caused by viral infections, is a major risk factor for the establishment of persistent or recurrent disease. Early-life wheezing and asthma exacerbations are triggered by common respiratory viruses, mainly rhinoviruses (RV), and to a lesser extent, respiratory syncytial virus, parainfluenza, human metapneumovirus, coronaviruses, adenoviruses, influenza, and bocavirus. The excess presence of bacteria, several of which are part of the microbiome, has also been identified in association with wheezing and acute asthma exacerbations, including haemophilus influenza, streptococcus pneumoniae, moraxella catarrhalis, mycoplasma pneumoniae, and chlamydophila pneumonia. While it is not clear when asthma starts, its characteristics develop over time. Airway remodeling already appears between the ages of 1 and 3 years of age even prior to the presence of atopic inflammation or an asthma diagnosis. The role of genetic defect or variations hampering the airway epithelium in response to environmental stimuli and severe disease morbidity are now considered as major determinants for early structural changes. Repeated viral infections can induce and perpetuate airway hyperresponsiveness. Allergic sensitization, that often precedes infection-induced wheezing, shifts inflammation toward type-2, while common respiratory infections themselves promote type-2 inflammation. Nevertheless, most children who wheeze with viral infections during infancy and during preschool years do not develop persistent asthma. Multiple factors, including illness severity, viral etiology, allergic sensitization, and the exposome, are associated with disease persistence. Here, we summarize current knowledge and developments in infection epidemiology of asthma in children, describing the known impact of each individual agent and mechanisms of transition from recurrent wheeze to asthma.

Basic clinical management of preschool wheeze

Preschool wheeze is very common and often difficult to treat. Most children do not require any investigations; only a detailed history and physical examination to ensure an alternative diagnosis is not being missed; and the differential diagnosis, and hence investigation protocols for the child in whom a major illness is suspected, shows geographical variation. The pattern of symptoms may be divided into episodic viral and multiple trigger to guide treatment, but the pattern of symptoms must be re-assessed regularly. However, symptom patterns are a poor guide to underlying pathology. Attention to the proper use of spacers, and adverse environmental exposures such as tobacco smoke exposure, is essential. There are no disease-modifying therapies, so therapy is symptomatic. This paper reviews recent advances in treatment, including new data on the place of leukotriene receptor antagonists, prednisolone for acute attacks of wheeze, and antibiotics, based on new attempts to understand the underlying pathology in a way that is clinically practical.

How to Choose the Correct Drug in Severe Pediatric Asthma

When a child with severe asthma (asthma defined clinically for the purposes of this review as wheeze, breathlessness, and chest tightness sometimes with cough) does not respond to treatment, it is important to be sure that an alternative or additional diagnosis is not being missed. In school age children, the next step is a detailed protocolized assessment to determine the nature of the problem, whether within the airway or related to co-morbidities or social/environmental factors, in order to personalize the treatment. For example, those with refractory difficult asthma due to persistent non-adherence may benefit from using budesonide and formoterol combined in a single inhaler [single maintenance and reliever treatment (SMART)] as both a reliever and preventer. For those with steroid-resistant Type 2 airway inflammation, the use of biologicals such as omalizumab and mepolizumab should be considered, but for mepolizumab at least, there is a paucity of pediatric data. Protocols are less well developed in preschool asthma, where steroid insensitive disease is much more common, but the use of two simple measurements, aeroallergen sensitization, and peripheral blood eosinophil count, allows the targeted use of inhaled corticosteroids (ICSs). There is also increasing evidence that chronic airway infection may be important in preschool wheeze, increasing the possibility that targeted antibiotics may be beneficial. Asthma in the first year of life is not driven by Type 2 inflammation, so beyond avoiding prescribing ICSs, no evidence based recommendations can be made. In the future, we urgently need to develop objective biomarkers, especially of risk, so that treatment can be targeted effectively; we need to address the scandal of the lack of data in children compared with adults, precluding making evidence-based therapeutic decisions and move from guiding treatment by phenotypes, which will change as the environment changes, to endotype based therapy.

Challenging the paradigm: moving from umbrella labels to treatable traits in airway disease

Airway diseases were initially described by nonspecific patterns of symptoms, for example "dry and wheezy" and "wet and crackly". The model airway disease is cystic fibrosis, which has progressed from nonspecific reactive treatments such as antibiotics for airway infection to molecular sub-endotype, proactive therapies with an unequivocal evidence base, early diagnosis, and biomarkers of treatment efficacy. Unfortunately, other airway diseases lag behind, not least because nonspecific umbrella labels such as "asthma" are considered to be diagnoses not mere descriptions. Pending the delineation of molecular sub-endotypes in other airway disease the concept of treatable traits, and consideration of airway disease in a wider context is preferable. A treatable trait is a characteristic amenable to therapy, with measurable benefits of treatment. This approach determines what pathology is actually present and treatable, rather than using umbrella labels. We determine if airway inflammation is present, and whether there is airway eosinophilia which will likely respond to inhaled corticosteroids; whether there is variable airflow obstruction due to bronchoconstriction which will respond to β2-agonists; and whether there is unsuspected underlying airway infection which should be treated with antibiotics unless there is an underlying endotype which can be addressed, as for example an immunodeficiency. The context of airway disease should also be extrapulmonary comorbidities, social and environmental factors, and a developmental perspective, particularly this last aspect if preventive strategies are being contemplated. This approach allows targeted treatment for maximal patient benefit, as well as preventing the discarding of therapies which are useful for appropriate subgroups of patients. Failure to appreciate this almost led to the discarding of valuable treatments such as prednisolone.

EDUCATIONAL AIMS

To use cystic fibrosis as a paradigm to show the benefits of the journey from nonspecific umbrella terms to specific endotypes and sub-endotypes, as a road map for other airway diseases to follow.Demonstrate that nonspecific labels to describe airway disease can and should be abandoned in favour of treatable traits to ensure diagnostic and therapeutic precision.Begin to learn to see airway disease in the context of extrapulmonary comorbidities, and social and environmental factors, as well as with a developmental perspective.

Addressing the risk domain in the long-term management of pediatric asthma

There is growing concern regarding the long-term outcomes of early and poorly controlled childhood asthma, either of which can potentially lead to the development of severe asthma in adults and irrecoverable loss of lung function leading to chronic obstructive pulmonary disease. These outcomes of inadequately controlled asthma should prompt a change in practice to better and/or earlier identify children at risk of adverse respiratory outcomes of asthma, to monitor disease progression, and to design intervention strategies that could either prevent or reverse asthma progression in children. The careful follow-up of spirometry over time-in the form of lung function trajectories, the application of biomarkers to assist in the diagnosis of early asthma and medication selection for these patients, as well as methods to identify patients at risk of asthma attacks-can be used to develop individualized management strategies for children with asthma. It is now time for asthma specialists to communicate this information to patients, parents, and primary care physicians and to incorporate them into routine clinical assessments of children with asthma. In time, these concepts of risk management and prevention can be refined to provide a more comprehensive approach to asthma care so as to prevent adverse respiratory outcomes from poorly controlled childhood asthma.

Severe asthma in children: therapeutic considerations

PURPOSE OF REVIEW

Children with poor asthma control despite maximal maintenance therapy have problematic severe asthma (PSA). A step-wise approach including objective adherence monitoring and a detailed multidisciplinary team assessment to identify modifiable factors contributing to poor control is needed prior to considering therapy escalation. Pathophysiological phenotyping in those with true severe therapy-resistant asthma (STRA) and the current array of add-on therapies will be discussed.

RECENT FINDINGS

Adherence monitoring using electronic devices has shown that only 20-30% of children with PSA have STRA and need additional therapies. Omalizumab and mepolizumab are licensed for children with STRA aged 6 years and older. Although robust safety and efficacy data, with reduced exacerbations, are available for omalizumab, biomarkers predicting response to treatment are lacking. Paediatric safety data are available for mepolizumab, but efficacy data are unknown for those aged 6-11 years and minimal for those 12 years and older. A sub-group of children with STRA have neutrophilia, but the clinical significance and contribution to disease severity remains uncertain.

SUMMARY

Most children with PSA have steroid sensitive disease which improves with adherence to maintenance inhaled corticosteroids. Add-on therapies are only needed for the minority with STRA. Paediatric efficacy data of novel biologics and biomarkers that identify the optimal add-on for each child are lacking. If we are to progress toward individualized therapy for STRA, pragmatic clinical trials of biologics in accurately phenotyped children are needed.

Airway symptoms and atopy in young children prescribed asthma medications: A large-scale cohort study

Diagnosing asthma and deciding treatment are difficult in young children. An inappropriate and too high prescription rate of inhaled corticosteroids (ICS) is suggested, but how airway symptoms are associated with prescriptions of asthma medication is less known. We studied how strongly wheeze, lower respiratory tract infections (LRTI), and atopic diseases are associated with dispensing of asthma medications during early childhood. We used data from the Norwegian Mother and Child Cohort Study and the Norwegian Prescription Database at four age-intervals (0-6, 6-18, 18-36 months, and 3-7 years). Primary outcomes were dispensed asthma medications (no medication, short-acting β-2 agonist, or ICS). Relative risks (RRs) and average attributable fractions (AAFs) were estimated. Both wheeze and LRTI were positively associated with both medication groups (0-6 months: no data on wheeze). The RRs and AAFs were higher for wheeze than LRTI. For ICS, the AAFs (95% CI) for wheeze vs LRTI were: 6 to 18 months: 69.2 (67.2, 71.2)% vs 10.4 (9.0, 11.8)%, 18 to 36 months: 33.0 (30.5, 35.5)% vs 10.0 (8.0, 12.0)%, and 3 to 7 years: 33.7 (31.0, 36.5)% vs 1.2 (0.5, 1.9)%. Except at 3 to 7 years of age, the AAFs were lower for atopic diseases than for LRTI and wheeze. Atopic diseases modified the associations between wheeze and ICS at 18 to 36 months and between LRTI or wheeze and ICS at 3 to 7 years. In conclusion, both wheeze and LRTI were associated with prescriptions of asthma medications in young children, with the strongest associations seen for wheeze. Atopic diseases contributed to these associations only in the oldest age groups.

Can early intervention in pediatric asthma improve long-term outcomes? A question that needs an answer

OBJECTIVE

Although many children with asthma do not experience persistence into adulthood, recent studies have suggested that poorly controlled asthma in childhood may be associated with significant airflow obstruction in adulthood. However, data regarding disease progression are lacking, and clinicians are not yet able to predict the course of a child's asthma. The goal of this article was to assess the current understanding of childhood asthma treatment and progression and to highlight gaps in information that remain.

DATA SOURCES

Nonsystematic PubMed literature search and authors' expertise.

STUDY SELECTION

Articles were selected at the authors' discretion based on areas of interest in childhood asthma treatment and progression into adulthood.

RESULTS

Uncontrolled asthma in early childhood can potentially have lasting effects on lung development, but it is unclear whether traditional interventions in very young children preserve lung function. Although not all children respond to standard interventions, certain asthma phenotypes have been identified that can help to understand which children may respond to a particular treatment.

CONCLUSION

Clinicians should monitor children's asthma control and pulmonary function over time to assess the long-term impact of an intervention and to minimize the effect of uncontrolled asthma, especially exacerbations, on lung development. New biologic therapies have shown promise in treating adults with severe, uncontrolled asthma, and some of these therapies are approved in the United States for children as young as age 6. However, knowledge gaps regarding the efficacy and safety of these treatments in younger children hamper our understanding of their effect on long-term outcomes.

Management of asthma in children

This manuscript takes a challenging look at the management of asthma in childhood, in particular in the light of the recent Lancet commission. One of the central pillars of the Commission is the need to deliver personalized medicine for airway disease by deconstructing the airway into components of fixed and variable airflow obstruction, inflammation and infection. Before any treatment for asthma, a diagnostic workup is essential to exclude other conditions. A diagnosis of asthma needs to be based on objective evidence of bronchodilator sensitive variable airflow obstruction, eosinophilic airway inflammation and atopy. Most children with atopic asthma respond to low dose inhaled corticosteroids, sometimes requiring a long acting β-agonist. If the response is unsatisfactory, then, rather than escalate treatment, an approach for which there is little evidence, a full review of the child should be undertaken, including extrapulmonary comorbidities, adherence and adverse environmental influences. If these cannot or will not be addressed by the family, then further treatment including biologicals may be indicated. Asthma attacks are an important warning sign and should always be taken seriously, including a focused reassessment of all aspects of the management of the child. Finally, preschool children with wheeze can also be evaluated for eosinophilic airway inflammation using peripheral blood eosinophil count as a surrogate. It is essential that we start to deliver personalized medicine to children with airway disease.