Asthma Management Handbook
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Table. Confirming the diagnosis of asthma in a person using preventer treatment

Clinical profile

Lung function

Interpretation or action

Typical variable respiratory symptoms

Variable airflow limitation demonstrated

Consistent with asthma diagnosis.

Note: In a patient with a confirmed diagnosis of asthma, these features are consistent with sub-optimal (poor or partial) asthma control and suggest treatment should be reviewed.

Variable airflow limitation not demonstrated

Obtain historical documentation of variable airflow limitation if possible.

If not available, test again (either of):

  • Repeat lung function test during and after symptoms
  • Withhold bronchodilator treatment for required time§ then repeat spirometry before and 10–15 minutes after salbutamol.

If diagnosis still not confirmed, consider bronchial provocation (challenge) test.

Note: a negative challenge test would not rule out asthma in a person taking inhaled corticosteroids.

Consider referral to a specialist respiratory physician to confirm the diagnosis.

Current respiratory symptoms

Fixed (irreversible or incompletely reversible) airflow limitation (post-bronchodilator FEV1/FVC < lower limit of normal for age and FEV1 <80% predicted)

Obtain historical documentation of variable airflow limitation if possible.

Ask about age at onset of symptoms and whether there were typical asthma symptoms earlier in life.

Consider alternative (or additional) diagnosis (e.g. COPD in adults).

Consider referral to a specialist respiratory physician to confirm the diagnosis, if lung function does not improve after 3-6 months of treatment with inhaled corticosteroids.

Few respiratory symptoms

 

Variable airflow limitation not demonstrated

Obtain historical documentation of variable airflow limitation if possible.

If not available, consider back-titrating preventer by one step:

  • Reduce inhaled corticosteroid dose by 50%.
  • 2–3 weeks later reassess lung function by spirometry before and 1015 minutes after salbutamol.
  • If still no evidence of variable airflow limitation, consider stopping preventer treatment (with close monitoring) and repeating spirometry another 2–3 weeks later.

If preventer is ceased and symptoms do not return at 2–3 weeks, review within 6 months.

Table applies to patients taking maintenance inhaled corticosteroid or combination inhaled corticosteroid/long-acting beta2 agonist

§ When spirometry is performed as a diagnostic test, inhaled bronchodilators should be withheld before the test. Withholding times vary between medicines:

    •  at least 4 hours for short-acting beta2 agonists (e.g. salbutamol, terbutaline) and short-acting muscarinic antagonists (e.g. ipratropium)

    •  at least 12 hours for preventers containing long-acting beta2 agonists for which twice-daily dosing is recommended (e.g. formoterol, salmeterol)

    •  at least 24 hours for long-acting muscarinic antagonists (e.g. aclidinium, glycopyrronium, tiotropium) and preventers containing long-acting beta2 agonists with once-daily dosing (e.g. fluticasone furoate plus vilanterol).

Note: Requested withholding times may vary between centres that conduct formal lung function testing.

† For patients using inhaled corticosteroid/long-acting beta2 agonist combinations, reduce the dose of inhaled corticosteroid component by 50%. For those already using the lowest possible dose of inhaled corticosteroid/long-acting beta2 agonist combination, consider switching to low-dose inhaled corticosteroid or stopping preventer.

Before stepping down, document the patient's current asthma status and risk factors, and ensure that the person has a written asthma action plan and an appointment for asthma review.

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