How to diagnose asthma in children
Take a structured clinical history. Consider if low, moderate or high suspicion of asthma.
Specifically check for:
- Wheeze, cough or breathlessness
- Daily or seasonal variation in these symptoms
- Any triggers that make symptoms worse
- A personal or family history of atopic disorders
- Food allergies
- Comorbidities, including rhinitis, chronic rhinosinusitis, acid reflux, obesity, obstructive sleep apnoea, anxiety
Examine to identify expiratory polyphonic wheeze and signs of other causes or respiratory symptoms. Remember asthmatics can have a normal examination when well. Observe for other signs including hyper-inflated chest, eczema and transverse nasal crease.
Suspected asthma under 5 years
- Treat symptoms based on observation and clinical judgement, and review the child on a regular basis.
- Consider a trial of moderate dose Inhaled Corticosteroids (ICS) for 8 weeks for children experiencing:
- asthma related symptoms 3 times a week or more
- night time waking
- symptoms uncontrolled on a Short Acting Beta Agonist (SABA)
- After 8 weeks stop ICS and continue to monitor child symptoms
- If symptoms did not resolve during trial of ICS, review if alternative diagnosis is likely
- If symptoms resolved then reoccurred within 4 weeks of stopping ICS, restart ICS at a lower dose as first line maintenance therapy
- If symptoms resolved but reoccurred beyond 4 weeks after stopping ICS, repeat the 8 week trial of moderate dose ICS
- If uncontrolled on low dose of ICS, consider addition of 4mg Montelukast at bedtime. Review within 4 to 8 weeks
- If uncontrolled on low dose ICS and Montelukast, stop Montelukast and refer to a specialist
- If they still have symptoms of asthma when they turn 5 years old then attempt objective testing. Asthma can be coded at that point if the criteria below are met. Until then, code as 'suspected asthma'.
Suspected asthma 5 to 16 years
Consider objective testing, following algorithm below.
Lung function tests for children over 5 years
- Offer spirometry if a diagnosis of asthma is being considered
- Regard a FEV1/FVC below the lower limit of normal as a positive test for obstructive airway disease (obstructive spirometry)
- Do a bronchodilator reversibility test for children and young people with obstructive spirometry
- Regard an improvement in FEV1 of 12% or more as a positive test
- Offer Fractional Exhaled Nitric Oxide (FeNO) testing if there is diagnostic uncertainty and they have either:
- Normal spirometry or
- Obstructive spirometry with a negative bronchodilator reversibility test
- Regard a FeNO level of 35ppb or more as a positive test
- Be aware that if a child smokes, this can falsely lower FeNO levels. However, a high level remains useful in supporting a diagnosis of asthma
Peak expiratory flow variability
Monitor peak flow variability for 2 to 4 weeks in children and young people if there is diagnostic uncertainty and:
- Normal spirometry or
- Obstructive spirometry, irreversible airways obstruction (negative BDR) and a FeNO level of 35ppb or more
- FeNO is unavailable
Ask the child to take peak flow readings morning and night for 2 to 4 weeks. Regard a value of more than 20% overall variability as a positive test.
Consider asthma in a child over 5 years if:
If the child is unable to perform objective testing
- Continue to treat based on observation and clinical judgement
- Try doing tests again every 6 to 12 months until satisfactory results obtained
- Consider referral to specialist if child repeatedly cannot perform objective tests and is not responding to treatment
When to diagnose asthma in children and young people aged 5 to 16 years
Code asthma after demonstrating any objective variability and a response to treatment.
FeNO testing and Spirometry may not be available in all areas of West Yorkshire. If there is clear peak flow variability and a response to treatment, this may suffice.
Do not rule out other diagnoses if symptom control continues to remain poor after treatment.
Review the diagnosis after 6 weeks by repeating any abnormal tests and reviewing symptoms.
Making the diagnosis of asthma in Children video presented by Dr Katharine Hickman, GP respiratory lead for West Yorkshire.
Asthma: diagnosis, monitoring and chronic asthma management NICE guideline NG80, 2021
BTS/SIGN British guideline on the management of asthma: A national clinical guideline, 2019
Global Initiative for Asthma: Global Strategy for Asthma Management and Prevention, 2023