Asthma is one of the most common chronic diseases of childhood throughout the world, and the UK has one of the highest prevalence rates.1 Figures from Asthma UK estimate there are 1.1 million children in the UK with a diagnosis of asthma.2
Most diagnoses are made by primary care practitioners. Despite the UK's high prevalence rates, the diagnosis in children can pose a particular challenge.
Is it asthma?
Children are frequently seen in primary care with symptoms of wheeze and cough. Research suggests that up to 50 per cent of children experience these respiratory symptoms in the first six years of life.3 However, a large proportion of these children do not have asthma and are suffering from viral-induced wheeze.4
There are also a number of less common alternative diagnoses in children who wheeze. The challenge for the GP is to make an accurate diagnosis in situations when presenting symptoms are so similar.
The 2008 revised BTS/SIGN guidelines acknowledged this difficulty and the section on the diagnosis of asthma in both adults and children was completely rewritten to assist in this important process.5
The guidelines clearly state that the diagnosis of asthma remains a clinical one and the emphasis is on the GP to elicit a careful history on which to base further investigations and therapeutic trials of treatment.
As with most respiratory diseases in children, common clinical features seen in asthma are cough, wheeze, shortness of breath, difficulty breathing and chest tightness. Clinical features relating to these symptoms also increase the probability of asthma.
There are factors that increase the probability of a diagnosis of asthma. These include the presence of widespread wheeze heard on auscultation, a strong personal and family history of asthma or atopic disease, and a positive response to a trial of asthma treatment.
There are children that, following a clinical assessment, have an unclear diagnosis or show a poor response to asthma treatment. These individuals require further investigations, such as lung function testing or skin prick testing, to look for signs of atopy, which may help to confirm or refute the diagnosis.
Tests and investigations
In children, tests to observe for airflow obstruction, airways responsiveness and inflammation can assist in confirming a diagnosis of asthma.
However, these tests are limited to children who can perform them reliably and usually are not possible in pre-school children.
Peak expiratory flow (PEF) monitoring or spirometry can be undertaken in children from the age of five years. Diurnal variation in PEF can be measured over a period of two weeks, but asking children to monitor PEF at home twice a day can result in less than ideal recording of data.
With the wider use of spirometry, using forced expiratory manoeuvres can be particularly useful, especially if there is evidence of airflow obstruction.
Reversibility testing using a bronchodilator via a pressurised metered dose inhaler and spacer can support the diagnosis of asthma if there is a significant increase in FEV1 (>12 per cent from baseline).5
Allergy testing using skin prick tests to identify specific aeroallergens can help to identify allergic asthma.
It can also help to inform parents about the atopic nature of the disease and assist in targeting allergen avoidance; however, this is not readily available in primary care and requires referral to a specialist centre.
Once a diagnosis of asthma has been established, or when there is a high probability of asthma, a trial of treatment is indicated to alleviate the symptoms.
The treatment of asthma is based on reducing inflammation and relieving bronchoconstriction, with the level of treatment needed depending on the frequency and severity of the symptoms.
The BTS/SIGN guidelines use a stepwise approach to treatment. Treatment should be stepped up to improve control as needed, and stepped down to find and maintain the lowest controlling step.
In step one, intermittent use of beta-2 agonists (e.g. salbutamol 100 microgram - two puffs) is recommended on an 'as required' basis to relieve symptoms in any child with mild intermittent asthma.
Inhaled corticosteroids (e.g. beclometasone) are the recommended first choice preventer drug for children with asthma and are introduced at step two of the guidelines.
In children aged less than five years who are unable to take inhaled corticosteroids, leukotriene receptor antagonists (LTRAs; e.g. montelukast) are suggested as an effective first-line preventer therapy.
The majority of children will be managed effectively on these first two steps of treatment; however, there will be a small percentage who remain symptomatic and additional add-on therapies such as long-acting beta-2 agonists (e.g. salmeterol) in children aged five to 12 years and LTRAs in the under fives may be necessary to gain control of the asthma (step three).
However, prior to initiating any additional treatments, it is important to check the child's inhaler technique as well as the parents' understanding of the medication, and to address any concerns they have.
When there is any doubt about the diagnosis of asthma or the child has persistent symptoms despite being on treatment, it is important to refer on to a specialist paediatrician.
The diagnosis is not always straightforward and we must ensure we treat those children that require treatment and not those with an alternative explanation for their symptoms.
Most children diagnosed with asthma are cared for in primary care and few will require treatment and support from the hospital specialist.
- Melanie McFeeters is a consultant nurse for children's respiratory diseases at University Hospitals of Leicester NHS Trust
|Clinical features that increase the probability of asthma5|
More than one of the following symptoms: wheeze, cough, difficulty breathing and chest tightness; particularly if these symptoms are:
1. Pearce N, Ait-Khaled N, Beasley R et al. Worldwide trends in the prevalence of asthma symptoms: phase III of the International Study of Asthma and Allergies in Childhood (ISAAC). Thorax 2007; 62: 758-66.
2. Asthma UK. Annual Report: Review 2007-2008. London Asthma UK 2009. Available at http://www.asthma.org.uk
3. Martinez FD, Wright AL, Taussig LM, Holberg CJ, Halonen M, Morgan WJ. Asthma and wheezing in the first six years of life. N Engl J Med 1995; 332: 133-8.
4. Townshend J, Hails S, McKean M. Diagnosis of asthma in children. BMJ 2007; 335:198-202.
5. BTS/SIGN. British guideline on the management of asthma: a national clinical guideline. Revised edition May 2009. Available at http://www.brit-thoracic.org.uk