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​How BTS/SIGN and NICE guidelines differ on asthma diagnosis

Read the differing recommendations on diagnosis in the draft BTS/SIGN and NICE draft guidelines 

BTS/SIGN draft guidelines on management of asthma

  • GPs should use the initial structured clinical assessment to estimate the probability of asthma.
  • For patients with a high probability, record ‘suspected asthma’ and start a carefully monitored trial of treatment (typically six weeks of inhaled corticosteroids). A good response to treatment, based on symptom questionnaire findings and/or lung function tests – either FEV1 or home serial PEF – is enough to confirm the diagnosis, but GPs must record the basis on which the diagnosis was made.
  • Patients with an intermediate probability - either on initial assessment or after a failed trial of treatment - should undergo spirometry and, if positive, reversibility tests and/or a trial of therapy. If they have normal spirometry, they should undergo bronchial challenge tests and/or FeNO measurement.
  • For patients in whom the probability of asthma is low, investigate possible alternative diagnoses and/or refer for further asthma tests


NICE: diagnosis and monitoring of asthma – interim guidance

  • For all patients over five, GPs should perform objective tests (including spirometry and FeNO) at the time of presentation, or once acute symptoms have been controlled.
  • Do not make a formal diagnosis of asthma until objective tests have been done.
  • Offer a FeNO test if a diagnosis of asthma is being considered in anyone over 16, or in children over five if they have normal spirometry, or obstructive spirometry but negative bronchodilator reversibility

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