Need to know - asthma
Professor Neil Barnes gives Dr Graham Archard some helpful advice on tricky aspects of asthma care
Professor Neil Barnes gives Dr Graham Archard some helpful advice on tricky aspects of asthma care
1. The consensus used to be that a child could not get asthma until one year of age because bronchiolar muscles are not developed until then. This does not seem to be reflected in practice. Is this actually correct?
Later studies using more sophisticated techniques have clearly shown that there are functioning ß-2 receptors on airway smooth muscle below this age and that they do respond to ß-2 agonists.
2. There is a lot of talk about referring children with asthma for allergy testing – but if we did it for all of them the service would be swamped. Is this necessary and, if so, for which group of patients?
The UK asthma guidelines have looked at the issue of skin testing and do not recommend its routine use in the management of either childhood or adult asthma.
About 30% of the population are atopic, that is they are skin test reactors, and if you do skin tests to common allergens such as house dust mite, grass, pollen and animal fur, they will show a reaction.
However, only a minority of these individuals will have any allergic disease such as asthma or rhinitis. Thus skin-prick testing turns up a lot of false positives.
The most important factor in diagnosing an allergy is the history. If individuals worsen on exposure to dust or grass pollen it is almost certain that that is what they are allergic to.
Another problem with skin-prick testing is that once an allergen has been identified it is only of value if there is a therapeutic option. Well-conducted trials and meta-analyses of house dust mite avoidance have not shown evidence of any benefit in asthma.
If an individual is allergic to animals from their history it can be recommended the family gets rid of the pet but in practice few do this.
New forms of immunotherapy are becoming available and licensed but at the moment these are mainly for the treatment of allergic rhinitis. Until there is good evidence that they are of benefit in asthma it is unlikely that routine skin testing of children will be recommended.
3. Do you support the concept of ‘wheezy bronchitis' – an acute URTI with wheeze that is not asthma?
The term ‘wheezy bronchitis' was frowned on some years ago as it became evident that many children with asthma were being misdiagnosed as having chest infections or bronchitis and were getting repeated courses of antibiotics before the correct diagnosis of asthma was recognised.
Studies over a number of years have shown there are two broad patterns of wheezing disease in under-fives, once unusual but important conditions such as cystic fibrosis or foreign body inhalation have been excluded.
There are pre-school children who develop asthma, and they are usually atopic. There is a second group who get what is now termed ‘viral-associated wheeze'. These children seem to be born with slightly smaller airways and when they develop a viral infection the inflammation and oedema causes narrowing and they get wheezy.
As they grow older and their lung size increases this no longer occurs and they usually grow out of it by the age of five.
Although in studies one can differentiate between true atopic asthmatics and viral-associated wheeze, in clinical practice the distinction is more difficult.
Factors that favour asthma are a family history of atopy, the child having other atopic disorders such as rhinitis or eczema and the symptoms occurring in situations other than viral infections.
Factors suggesting viral-associated wheeze are lack of family history or personal history of atopy, and lack of interval symptoms – between viral infections the child is well.
The importance of differentiating these two conditions is that parents can be reassured their child will grow out of the viral-associated wheeze.
Viral-associated wheeze can be treated purely symptomatically with bronchodilators.
There is little evidence that inhaled steroids prevent viral-associated wheeze, although there is some evidence that the leukotriene receptor montelukast may have a beneficial effect. In contrast, asthma in the under-fives does respond to inhaled steroids.
4. At what age can a child use a mask and inhaler effectively?
Very young children can use a spacer and mask if the parents are shown how to use them correctly. Over the age of about seven years, children are able to use dry powder inhalers and some patients prefer them.
5. Is there any place for oral ß-agonists these days?
In adults there is almost no role for oral ß-2 agonists. Inhaled long-acting ß-2 agonists are more effective with fewer side-effects and there is no evidence that adding an oral ß-2 agonist when somebody is on a long-acting ß-2 agonist is of value.
In children, the preferred method for delivering a ß-2 agonist is by inhalation and and oral ß-2 agonist is rarely needed.
6. We are told asthma is becoming more common – but I cannot remember the last time I gave intravenous aminophylline or used a nebuliser. I used to do this every other week. What is going on?
There is evidence in the UK that the prevalence of asthma has risen markedly over the last two or three decades although recent studies suggest that prevalence may now be slightly decreasing. Although the prevalence of asthma has risen we now have a range of very effective treatments for the majority of patients, with inhaled steroids being the most important and inhaled long-acting ß-2 agonists being very effective add-ons.
By using these drugs appropriately the risk of acute severe asthma is markedly decreased and therefore many fewer patients need emergency treatment. This is borne out by the fact that, despite the rise in prevalence of asthma, the asthma death rate in the UK has fallen – as have hospital admissions.
7. What are the current views on the cause of increased asthma prevalence? How relevant are cleaner living or smaller families?
The cause of the increased prevalence of asthma is likely to be multifactorial.
A change in genetic makeup cannot be the cause as genes don't change over a two- to three-decade time-span, so the change has to be environmental.
The so-called hygiene hypothesis has quite a lot of evidence behind it. The hypothesis is that infections, probably gut infections, early in childhood seem to protect against the development of asthma and atopic disorders. The protective effect of viral infections explains why there is more asthma in small families and in first-born children as there is less exposure to viral infections from siblings.
Other factors probably modulate the prevalence of asthma. There is clear evidence that women who smoke in pregnancy or parents who smoke are more likely to have children with asthma. There may be also some effect of diet.
The effect of air pollution is probably more to increase symptoms in somebody who has asthma rather than to cause it in the first place. This is an area of very active research as clearly, if we could identify why people develop asthma, we could recommend prevention strategies.
However, the UK asthma guidelines, which have looked at this very carefully, state that at present no prevention strategies, beyond advising parents not to smoke, can be recommended.
8. What proportion of children ‘grow out' of asthma – and is it reasonable to advise patients that a child might do just this?
As children go through puberty, approximately 50% will either have a marked improvement in their asthma or the asthma will seem to go away. Asthma seems to remit during puberty if it is mild and if the child has had few hospital admissions.
It is unclear if better treatment and control of asthma increases the likelihood of asthma going away. However, it is safe to say that we almost never see young adults with deformed chests such as Harrison's sulcus, which I saw when I first did respiratory medicine. But even if asthma does away through puberty, it may come back in later life.
9. Most, if not all, people with acute asthma who are admitted seem to be started on antibiotics, although before admission there does not appear to be any sign of infection. Is this correct practice and, if so, should we treat all acute asthma attacks with antibiotics?
The most common cause of asthma exacerbations is viral URTIs, allergen exposure and stopping controller medication, particularly inhaled steroids. Bacterial infections are quite unusual as a cause of an acute severe asthma attack. The UK asthma guidelines therefore give a grade A recommendation not to give antibiotics routinely for an exacerbation of asthma.
Blinded placebo-controlled trials have failed to show any benefit for antibiotics for asthma exacerbations. Asthma patients may complain of cough and sputum during an exacerbation but even this is not a sign of an infection as allergic inflammation with eosinophils causes sputum to go yellow or green.
10. Is there anything new on the horizon for the treatment of asthma?
There is very active research on new treatments for asthma. In the next few years we are likely to see inhaled steroids and ultra-long-acting ß-2 agonists that can be given as combinations once a day.
There are treatments being developed for severe and difficult asthma, but these are still at an experimental phase. It is likely that these treatments will only work in a proportion of severe asthma, and individual patients will need to be carefully chosen for these treatments, which are likely to be quite expensive.
The biggest impact on improving asthma care in the next five to 10 years is likely to be from better delivery of care. In this respect, data from Finland and Sweden has shown that, with the currently available drugs and better organised care, a 90% reduction in hospital admissions can be achieved.
11. Is there a place of oral antihistamines in the management of asthma?
Antihistamines have no effect in the management of asthma. However, they are extremely important in the management of allergic rhinitis and allergic conjunctivitis.
12. Many GPs now use questionnaires for review of patients with stable asthma – time off work/school, disturbed sleep and effects on daily activities rather than a full clinical review. Is this a safe management plan?
A face-to-face consultation with asthma patients is still very important to determine if their asthma is controlled. There are a number of questionnaires that can aid this process such as the RCP3 questions (see below), the Asthma Control Test (ACT) and the Asthma Control Questionnaire (ACQ), which is attached.
Professor Neil Barnes is professor of respiratory medicine at St Bartholomew's and the London Hospital Medical College. He is also spokesperson for the British Lung Foundation
Competing interests None declared
Breathe Easy Week (16-22 June) is the British Lung Foundation's annual awareness campaign. This year, the charity will be encouraging everyone to take ‘big breaths' by looking after their lungs and following the BLF's Airway Code, a 10-point guide to lung health. For more information, contact the BLF's helpline on 08458 505020 or visit www.bigbreaths.org
Child with peak flow meter What I will do now
Dr Archard responds to Professor Barnes's answers
• I shall be happy to diagnose asthma more confidently in patients under a year old and be confident of the effectiveness of ß-agonists
• I am pleased that we should not be routinely referring for allergy testing
• So, virally induced wheeze does exist, and patients do not have to carry a lifelong diagnosis of asthma because of a single episode of wheeze
• I shall consider using dry powders in the over-sevens
• I am reassured that the improved management of asthma has resulted in the decrease in emergencies – we need to keep up the good work
Dr Graham Archard is a GP in Christchurch, Dorset