Environmental factors relevant to difficult asthma

doi:10.1016/S1526-0542(02)00187-2

Paediatric Respiratory Reviews

Volume 3, Issue 3, September 2002, Pages 248-254

https://doi.org/10.1016/S1526-0542(02)00187-2 Get rights and content

Abstract

Symptom persistence in difficult asthmatics may be related to their home environment. If sensitised asthmatics are to benefit from indoor allergen avoidance measures, these must be rigorous and drug adherence satisfactory. This is difficult for many families.

The relationship between traffic pollution, asthma diagnosis and symptom severity is persuasive but requires objective validation.

Overall, it seems that house dust mite control and tobacco smoke avoidance are important for asthmatics and advice about how to avoid these adverse factors must be given. Whether these measures are effective in difficult asthmatics and whether moving house makes any difference is unknown.

Section snippets

DOES CURRENT ALLERGEN EXPOSURE AFFECT SYMPTOM SEVERITY IN SENSITISED ASTHMATICS?

It seems to be a consistent finding that in sensitised patients the current level of allergen exposure correlates with more severe disease, including hospitalisations, acute visits and school days missed.1., 2., 3. Since sensitised patients have more severe symptoms, it would be expected that sensitised difficult asthmatics have persistent symptoms because of high levels of allergen exposure. Is allergen reduction, or avoidance, the answer to symptom control?

WHAT IS THE ROLE OF ALLERGEN AVOIDANCE?

Numerous reviews have summarised and supported the role of allergen avoidance in asthma control.4., 5. There are two issues that should be considered when assessing this. Firstly, whether symptoms really do improve at low allergen levels – a small exposure may be all that is needed – and secondly whether the methods used to reduce allergen levels are effective.

Clinical trials, in children, have demonstrated benefit from mite avoidance measures but these have had small numbers of patients⁶ or

Indoor allergens

The relationship between “indoor” allergens and asthma has been examined more extensively than that with outdoor allergens. In urban communities this is of greater relevance since the majority of the day is spent indoors and exposure is perennial. The single most common indoor allergen that has been studied is the house dust mite. It has been highlighted as a key target for reduction.¹⁰ Nowadays, in developed countries, homes are better insulated and energy efficient, creating a warm, humid

DO SPECIFIC ALLERGENS CONTRIBUTE TO SEVERE ASTHMA?

In adults with severe asthma who lived in hospital in an allergen-free environment Call et al.²⁷ demonstrated that those with house dust mite sensitisation maintained peak flow values when the steroid dose was reduced. Those sensitised to fungal antigens deteriorated when steroids were reduced.²⁷ In the second part of this study, when factors associated with fatalities from asthma were retrospectively investigated, it was found that in five out of eight cases, exposure to a relevant allergen

OUTDOOR POLLUTANTS

Air pollutants are known to contribute to respiratory ill health³² but which in particular affect asthma? Is there a difference between urban and rural environments? Studies examining air pollutants and respiratory health have measured nitrogen dioxide, sulphur dioxide, carbon monoxide and ozone and related these to mortality, hospital admissions, respiratory symptoms and asthma.33., 34., 35. Current pollution levels in London have been related to short-term increases in casualty attendances of

Tobacco smoke

This is probably the most important indoor air pollutant contributing to symptoms in established asthma.⁵¹ In younger children with asthma this includes passive smoking, but in older children and adolescents (who make up a large portion of difficult asthmatics) both active and passive smoking become an issue. Elimination of tobacco smoke from the environment is important for asthmatics⁵² and exposure is related to severity.⁵³ Plainly, patients with asthma, especially those with severe symptoms,

SUMMARY

There is some evidence that children with difficult asthma are more likely to live in homes where there is tobacco smoking and which are damp. However, there is no good evidence that moving house will benefit them. There is some evidence that living close to heavy traffic is related to asthma but further evaluation of this relationship is needed.

The only formal public health advice informed by research is the avoidance of active smoking in pregnancy, since this is related to respiratory

PRACTICE POINTS

•
There is a strong association between allergen sensitisation and asthma.
•
There is a relationship between the level of allergen exposure and symptom severity in sensitised asthmatics.
•
Avoidance measures for indoor allergens should be recommended for difficult asthmatics.
•
Compliance with avoidance may be a problem.
•
There is no clear link between asthma severity and either air pollution or urban living.
•
Smoking is an independent risk factor in increasing asthma symptoms and should be avoided.

RESEARCH DIRECTIONS

•
Is early exposure to infection the key in preventing allergen sensitisation?
•
Should induction of tolerance with allergen exposure be pursued further?
•
What is the role of food allergy in severe asthma?
•
Does air pollution influence severity of symptoms?
•
Does re-housing from damp conditions alter symptom control?

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Our findings suggest that uncontrolled asthma is common among adults and can be impacted by several factors. Effective asthma control programs are needed to improve asthma management and reduce unnecessary healthcare utilization.
A home visit program for low-income African American children with asthma: Caregivers' perception of asthma triggers and a gap in action
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Additionally, although indoor asthma triggers are critical in controlling asthmatic symptoms, many failed to identify many of those, such as roaches, molds, and pets and have the adequate resources or power to take action (e.g., requesting pest management to landlords). Overall findings show that home environments were suboptimal for the management and control of child asthma conditions (Saglani & McKenzie, 2002). Knowledge about at-home triggers as well as the actions and efforts by caregivers and landlords to mitigate these was inadequate.
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Families with children with moderate to severe asthmatic symptoms who had been recently hospitalized or in the emergency room were invited to participate in a home visit program. As part of the home visit, caregivers of the asthmatic children were asked a series of questions on asthma triggers and the measures for eliminating the triggers (N = 218).
Findings show a gap between caregivers' perception of asthma triggers and the actions to mitigate or avoid such triggers.
Overall findings show that home environments were suboptimal for the management and control of child asthma conditions. Knowledge about home triggers as well as the actions and efforts by caregivers and landlords to mitigate these was found to be inadequate. Even when caregivers are aware of the presence of at-home triggers, actions to minimize exposure to the trigger do not always follow due to a lack of power, resource, and knowledge.
The findings raise the need for additional research to investigate the reasons for the lack of actions, advocacy for low-income families to live in a healthy environment, continued education and empowerment, and patient/caregiver-doctor partnership. Additionally, the provision of community support through community advocacy and training of culturally competent healthcare providers are needed for the successful management of pediatric asthma among African American children.
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Other publications advocate the opinion that while asthma can exacerbate despite supreme therapy adherence [66] (potentially, due to the complex biological nature of this disease [67]), poor adherence almost inevitably leads to poor asthma control [68]. In this regard, mHealth technology can enable an instantaneous alert about dangerous levels of extrinsic factors (e.g., pollen counts [69], air pollution [70], or viral factors [71–73]) that commonly trigger an asthma exacerbation. While attractive, mHealth monitoring, especially if it is smartphone- and app-based, encounters certain barriers in the pediatric setting.
Mobile (m) Health technology is well-suited for Remote Patient Monitoring (RPM) in a patient’s habitual environment. In recent years there have been fast-paced developments in mHealth-enabled pediatric RPM, especially during the COVID-19 pandemic, necessitating evidence synthesis. To this end, we conducted a scoping review of clinical trials that had utilized mHealth-enabled RPM of pediatric asthma. MEDLINE, Embase and Web of Science were searched from September 1, 2016 through August 31, 2021. Our scoping review identified 25 publications that utilized synchronous and asynchronous mHealth-enabled RPM in pediatric asthma, either involving mobile applications or via individual devices. The last three years has seen the development of evidence-based, multidisciplinary, and participatory mHealth interventions. The quality of the studies has been improving, such that 40% of included study reports were randomized controlled trials. In conclusion, there exists high-quality evidence on mHealth-enabled RPM in pediatric asthma, warranting future systematic reviews and/or meta-analyses of the benefits of such RPM.
Prevalence and clinical profile of difficult-to-control severe asthma in children: Results from pneumology and allergy hospital units in Spain
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Although the factors that contribute to asthma being difficult-to-control are not clearly identified,12 some studies show a slight association with genetic or environmental factors.12,37 Food allergies,38 allergic rhinitis,39 and especially the HRQoL40 are considered associated with difficult-to-control asthma. One limitation of this study may arise from its observational design.
Severe asthma is often poorly controlled and its prevalence in Spanish children is unknown. The aim was to determine the prevalence of difficult-to-control severe asthma in children, the agreement of asthma control between physicians and Spanish Guidelines for Asthma Management (GEMA), and the health-related quality of life (HRQoL) for children and parents.
Observational, cross-sectional, two-phase, multicentre study. In the first phase, all children who attended pneumology and allergy units during a three-month period were classified according to physicians’ criteria as patients with: asthma, severe asthma, or difficult-to-control severe asthma. Patients aged 6–14 years with severe asthma (difficult-to-control or controlled) were included in the second phase.
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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.
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SERIES: DIFFICULT ASTHMA – HOW SHOULD WE APPROACH THE PROBLEMEnvironmental factors relevant to difficult asthma

Abstract

Section snippets

DOES CURRENT ALLERGEN EXPOSURE AFFECT SYMPTOM SEVERITY IN SENSITISED ASTHMATICS?

WHAT IS THE ROLE OF ALLERGEN AVOIDANCE?

Indoor allergens

DO SPECIFIC ALLERGENS CONTRIBUTE TO SEVERE ASTHMA?

OUTDOOR POLLUTANTS

Tobacco smoke

SUMMARY

PRACTICE POINTS

RESEARCH DIRECTIONS

Ann. Allergy Asthma Immunol.

J. Allergy Clin. Immunol.

J. Allergy Clin. Immunol.

J. Allergy. Clin. Immunol.

J. Am. Diet. Assoc.

Respir. Med.

Lancet

Pub. Health

Asthma severity and morbidity in a population sample of Sydney schoolchildren: Part II: importance of house dust mite allergens

Aust. NZ. J. Med.

Home environment and severe asthma in adolescents. A population based case–control study

BMJ

On allergens and asthma (again): does exposure to allergens in homes exacerbate asthma?

Clin. Exp. Allergy

Allergen avoidance in the treatment of asthma and atopic disorders

Thorax

Environmental control: an idea whose time has come

Eur. Respir. J.

The respiratory effects of reduction of mite allergen in the bedrooms of asthmatic children – a double-blind controlled trial

Clin. Exp. Allergy

House dust mite control measures in the management of asthma: meta-analysis

BMJ

Importance of indoor allergens in the induction of allergy and ellicitation of allergic disease

Allergy

The importance of housing characteristics in determining Der p 1 levels in carpets in New Zealand homes

Clin. Exp. Allergy

Crane J. House dust mite allergens in pillows

BMJ

Relationship between mite, cat, and dog allergens in reservoir dust and ambient air

Allergy

Quantification of house dust mite allergens in ambient air

Rev. Environ. Health

Genetic and environmental risk factors for asthma: a cotwin–control study

Am. J. Respir. Crit. Care. Med.

Low domestic exposure to house dust mite allergens (Der p 1) is associated with a reduced non-specific bronchial hyper-responsiveness in mite-sensitised asthmatic subjects under optimal drug treatment

Clin. Exp. Allergy

Benefits of high altitude allergen avoidance in atopic adolescents with moderate to severe asthma, over and above treatment with high dose inhaled steroids

Clin. Exp. Allergy

Effectiveness of and compliance to intervention measures in reducing house dust and cat allergen levels

Ann. Allergy Asthma. Immunol.

Influence of asthma education on asthma severity, quality of life and environmental control

Can. Respir. J.

Respiratory symptoms and home environment in children: a national survey

Thorax

Asthmatic symptoms and indoor levels of micro-organisms and house dust mites

Clin. Exp. Allergy

Reduction of indoor airborne mould spores

Allergy

SERIES: DIFFICULT ASTHMA – HOW SHOULD WE APPROACH THE PROBLEM
Environmental factors relevant to difficult asthma