Diagnosis in Children

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Summary of practice points Level of evidence
In young children, the diagnosis of asthma can be confirmed by a clinical response to an inhaled bronchodilator. [√]
In children aged 7 years and over, use spirometry to confirm the diagnosis of asthma. [√]
In young children, care is needed to exclude non-asthma causes of wheeze [√]
When cough is the predominant symptom of suspected asthma, careful assessment is needed to avoid making an incorrect diagnosis of asthma, or instigating inappropriate management. (IV)
Exercise-induced dyspnoea is not always due to asthma, even in children with a confirmed diagnosis of asthma  (IV)
Asthma management in children should be based on a careful assessment of the pattern of asthma. [√]

Asthma in children differs from asthma in adults in clinically important aspects, which include the patterns of asthma, natural history and anatomical factors. The pattern and severity of asthma in childhood vary widely. For the majority of children, asthma will resolve - or at least improve - with age.

Diagnosis

Practice points
  • In young children, the diagnosis of asthma can be confirmed by a clinical response to an inhaled bronchodilator. [√]
  • In children aged 7 years and over, use spirometry to confirm the diagnosis of asthma. [√]

In the majority of children, the diagnosis of asthma is based on a history of recurrent or persistent wheeze in the absence of any other apparent cause (Table 1).

  • Wheeze due to asthma is often accompanied by cough, shortness of breath, or both.
  • A history of associated eczema, urticaria or a history of asthma in a first degree relative supports the diagnosis.
  • In infants and toddlers, the first episode of wheeze may be difficult to distinguish from respiratory tract infections (acute bronchiolitis in infants or viral bronchitis in toddlers).

Tests to confirm the diagnosis

In young children, the diagnosis of asthma is usually confirmed by a clinical response to an inhaled bronchodilator.

  • Only children over 7 years old are likely to be able to perform spirometry or peak expiratory flow rate (PEF) measurement consistently and reliably, to enable an objective assessment of lung function and bronchodilator response.
  • Tests of bronchial hyperresponsiveness are rarely used in children.
  • Exercise testing can confirm exercise-induced asthma in children.
Table 1. Other causes of wheeze in young children
Condition Characteristics

Transient infant wheezing
  • Onset in infancy
  • No associated atopy
  • Associated with maternal smoking

Cystic fibrosis

Recurrent wheeze and failure to thrive

Inhaled foreign body

Sudden onset

Milk aspiration-cough during feeds

Especially liquids
Associated with developmental delay

Structural abnormality

Onset at birth

Cardiac failure

Associated with congenital heart disease

Suppurative lung disease

Early morning wet/moist cough 

Alternative diagnoses that are commonly confused with asthma

Practice tip

In new patients with a previous diagnosis of asthma, confirm that childhood recurrent non-specific cough has not been wrongly interpreted as asthma.
Recurrent non-specific cough

The pathophysiology of recurrent cough in the absence of wheeze appears differ from that of classic asthma and should not be confused with asthma.1 Recurrent non-specific cough is a very common symptom in children, particularly preschool-aged children. There is usually no associated atopy or family history of asthma. Usually the child develops a cough in association with an upper respiratory tract infection. Typically:

  • cough is dry
  • coughing occurs in short paroxysms
  • coughing is worse in the early hours of the morning and during exercise
  • the paroxysm of coughing may be followed by a vomit. In between paroxysms, the child is very well with no tachypnoea or wheeze
  • episodes last for 2-4 weeks
  • cough is non-responsive to therapy.

Recurrent non-specific cough usually resolves by age 6 or 7 years and leaves no residual pulmonary pathology.

When cough is due to asthma, it is usually accompanied by some wheeze and episodes of shortness of breath.

  • Cough can be the predominant symptom of asthma, but it is extremely rare for cough to be the only symptom.2
  • The concept of the "cough-variant asthma" syndrome was popularised in the mid-1980s and it has become an all-embracing label for the symptom of recurrent cough. This has resulted in overdiagnosis of asthma and inappropriate therapy.
Chronic suppurative lung disease

The symptoms of chronic suppurative lung disease (chronic bronchitis and bronchiectasis) can be mistaken for those of asthma. Typically, the child with chronic suppurative lung disease presents with a history of cough as the major symptom. The cough usually does not disturb the child's sleep but typically is most prominent as a moist cough on waking in the morning.

Exercise-induced respiratory symptoms

Exercise-induced symptoms are commonly reported in children with asthma.

  • Many children with asthma who report exercise-induced dyspnoea fail to demonstrate airflow limitation on formal exercise testing.3
  • Misinterpretation of dyspnoea as asthma potentially leads to overtreatment.
  • Exercise-induced laryngeal dysfunction, characterised by inspiratory stridor or acute air hunger, has recently been described in children and adolescents who are competitive athletes.4 Unlike vocal cord dysfunction, symptoms of laryngeal dysfunction usually only occur during competitive exercise and are difficult to reproduce in the laboratory.
Practice points
  • In young children, care is needed to exclude non-asthma causes of wheeze. [√]
  • When cough is the predominant symptom of suspected asthma, careful assessment is needed to avoid making an incorrect diagnosis of asthma, or instigating inappropriate management. (IV)
  • Exercise-induced dyspnoea is not always due to asthma, even in children with a confirmed diagnosis of asthma. (IV)
  • Asthma management in children should be based on a careful assessment of the pattern of asthma. [√]

Patterns of asthma in children

The pattern of asthma determines the need for preventive therapy in children.

Intermittent asthma

Intermittent (formerly termed ‘episodic') asthma is classified as infrequent or frequent.

Infrequent intermittent asthma

Infrequent intermittent asthma is the most common pattern, and occurs in 70%-75% of children with asthma (Figure 1).5 In infrequent intermittent asthma:

  • Children have isolated episodes of asthma lasting from 1-2 days up to 1-2 weeks
  • Episodes are usually triggered by an upper respiratory tract infection or an environmental allergen
  • Episodes are usually more than 6-8 weeks apart and children are asymptomatic in the interval periods.

Severity of infrequent intermittent asthma varies widely. Episodes are usually mild, but children with this pattern account for up to 60% of paediatric hospital admissions.

Children with infrequent intermittent asthma require treatment only during episodes. Regular preventive therapy is not recommended. For more information on the management of infrequent intermittent asthma, see Principles of Drug Therapy. 

Frequent intermittent asthma

Approximately 20% of children with asthma have frequent intermittent asthma:5

  • Episodes occur at intervals shorter than 6-8 weeks.
  • Children have minimal symptoms (e.g. exercise-induced wheeze) between episodes.

Frequent intermittent asthma is otherwise similar to infrequent intermittent asthma.

Children with frequent intermittent asthma may benefit from regular preventive therapy with leukotriene receptor antagonists, cromoglycate, nedocromil or low-dose (not greater than 200 mcg per day) inhaled corticosteroids. Preventive treatment is commonly required only during the winter months.

Persistent asthma

Approximately 5-10% of children with asthma have persistent asthma:5

  • Children have symptoms on most days, often including:
    • sleep disturbance due to wheeze or cough
    • early morning chest tightness
    • exercise intolerance
    • spontaneous wheeze.
  • Acute asthma episodes may also occur, as for intermittent asthma.

Severity ranges from mild (symptoms 4-5 days per week and readily controlled by low-dose preventive therapy) to severe (frequent severe symptoms and abnormal lung function requiring intensive therapy).

Figure 1. Frequency of asthma patterns in children

Adapted from Henderson et al, 2004 5 Three out of four children with asthma have infrequent intermittent asthma, while only one in twenty has persistent asthma.5 (Proportions differ between primary school-aged and preschool-aged children.)

Asthma classification in children

Classification of childhood asthma is based mainly on the clinical pattern. In children over 7 years old, spirometry and PEF variability are also useful factors to consider. Childhood asthma is classified as infrequent intermittent, frequent intermittent, mild persistent, moderate persistent or severe persistent. Patients with asthma of any category can experience mild, moderate or severe exacerbations.

Table 2 represents a reasonable approach to classifying asthma in children over age 5 years as a guide to the rational selection of initial therapy. It is intended as a guide only and the suggested categories are not definitive. Regular review of asthma control and response to treatment is essential to reassess the child's asthma pattern.

In children under 5 years, asthma diagnosis and classification rely mainly on clinical judgement, taking into account symptoms and physical findings.

For information on assessment of acute asthma in children, see Acute Asthma.

Table 2. Classifications of asthma in children over 5 years old
  Daytime symptoms
between exacerbations 		Night-time symptoms
between exacerbations 		Exacerbations PEF or FEV1* PEF variability**
Infrequent intermittent

Nil

Nil

Brief
Mild
Occur less than every 4-6 weeks

More than 80% predicted

Less than 20%
Frequent intermittent

Nil

Nil

More than 2 per month

At least 80% predicted

Less than 20%
Mild persistent

More than once per week but not every day

More than twice per month but not every week

May affect activity and sleep

At least 80% predicted

20-30%
Moderate persistent

Daily

More than once per week

At least twice per week
Restricts activity or affects sleep

60-80% predicted

More than 30%
Severe persistent

Continual

Frequent

Frequent

Restricts activity

60% predicted or less

More than 30% 

Adapted from GINA 2005 6

An individual's asthma category (infrequent intermittent, frequent intermittent, mild persistent, moderate persistent or severe persistent) is determined by the level in the table that corresponds to the most severe feature present. Other features associated with that category need not be present.

* Predicted values are based on age, sex and height
** Difference between morning and evening values
FEV1: Forced expiratory volume in 1 second; PEF: peak expiratory flow.