Asthma - Diagnosing Care Pathway

Review in progress

Disclaimer: The guidance contains helpful primary care information for management of referrals and up to date referral criteria. These guidelines are locality specific to best reflect local services. This guidance does not override or replace the individual responsibility of healthcare and social care professionals involved in the delivery of care to make informed professional judgements appropriate to the circumstances of the individual.


This guidance refers to:

  • The diagnosis of Asthma (in adults) in primary care

This guidance does not cover:

  • Acute presentation of Lower Respiratory Tract Infection.
  • Patients presenting with potential exacerbation of Asthma without prior diagnosis should be managed as per appropriate clinical guidance and an assessment and diagnosis confirmed during a period of stability


The diagnosis of asthma is clinical. There are no gold-standard diagnostic criteria and no unequivocal evidence-based recommendation on how to make a diagnosis of asthma.

Current guidance is to consider the following when making a diagnosis

  • An appropriate history (more than one of- wheeze, breathlessness, chest tightness, cough)
  • Tests influence the probability of asthma but do not prove a diagnosis
  • Asthma status and the outcome of tests can vary over time

History and examination

Factors that increase probability of asthma

  • Cough
  • Wheeze
  • Shortness of breath
  • Chest tightness
  • Symptom VARIABILITY, especially during the night and in the early morning.
  • Symptoms following exercise or exposure to trigger factors/ irritants.
  • Symptoms after aspirin, non-steroidal. anti-inflammatory drugs or β-blockers.
  • Childhood or family history of atopy including asthma.

Diagnostic and Action Algorithm based on clinical probability of asthma

High probability
  • Code as suspected asthma
  • Initiate treatment – Inhaled Corticosteroid for 6 weeks and review
  • Assess response objectively- use lung function or validated symptom score, record variability

If good response to treatment

  • Code as asthma, adjust medication dose, provide self-management support (including Asthma Control Plan, rescue medication and education) and arrange ongoing review

If poor response

  • proceed as for intermediate probability as asthma
Intermediate probability
  • Test for airway obstruction using spirometry
  • Test for bronchodilator reversibility either
    • Test for variability: PEF charting, challenge testing
    • Test for eosinophilic inflammation: blood eosinophilia, IgE, RAST, skin prick test
    • Watchful waiting if asymptomatic or commence treatment and assess response objectively

If good response to treatment

  • code as asthma, adjust medication dose, provide self-management support (including Asthma Control Plan, rescue medication and education) and arrange ongoing review

If poor response

  • proceed as for low probability as asthma
Low probability
  • Investigate for other diagnosis
  • If other diagnosis unlikely proceed as for intermediate probability of asthma

See Diagnostic Algorithm for further information

Suspected occupational asthma

Symptoms that improve when patient is not at work, adult onset asthma and workers in high-risk occupations, worsening since change in work, as patient if:

  • Have your asthma symptoms started as an adult, or have your childhood asthma symptoms returned since you started working?
  • Do you have other symptoms, such as rhinitis (sneezing, itchy, runny nose) or conjunctivitis (itchy, red, and inflamed eyes)?
  • Do your symptoms improve on the days you're not at work (when you're on holiday, for instance)?
  • Do your symptoms get worse after work, or disturb your sleep after work?

Differential Diagnoses

Asthma and COPD Overlap Syndrome (ACOS)

  • A significant proportion of patients who present with symptoms of a chronic airways disease have features of both asthma and COPD
  • Patients with features of both asthma and COPD experience frequent exacerbations, have poor quality of life, a more rapid decline in lung function and higher mortality than asthma or COPD alone
  • Concurrent clinician diagnosed asthma and COPD has been reported in between 15% and 20% of patients
  • Distinguishing asthma from COPD can be problematic, particularly in smokers and older adults
  • ACOS is characterised by persistent airflow limitation with several features usually associated with asthma and several features usually associated with COPD
  • ACOS is therefore identified by the features that it shares with both asthma and COPD
  • Please also see referral criteria

Read Codes

  • Asthma SytsmOne/EMIS
  • ACOS code on SytsmOne Xac33 / EMIS H3B

See The diagnosis of asthma in adults for summary overview

Red Flags

Seek immediate or urgent specialist advice/treatment if:

  • Prominent systemic features (myalgia, fever, weight loss)
  • Unexpected clinical findings (eg crackles, clubbing, cyanosis, cardiac disease, monophonic wheeze or stridor)
  • Persistent non-variable breathlessness
  • Chronic sputum production
  • Unexplained restrictive spirometry
  • Chest X-ray shadowing
  • Marked blood eosinophilia
  • Patient or parental anxiety or need for reassurance


Spirometry and bronchodilator reversibility

  • Spirometry is the preferred investigation for identifying airflow obstruction using lower limit of normal
  • Normal spirometry in an asymptomatic patient does not exclude asthma
  • Consider other causes for airflow obstruction based on history (e.g. COPD, chronic bronchitis, bronchiectasis)
  • A combined diagnosis of both asthma and COPD is possible and treatment should aim to fully treat the reversible component

Demonstrating variability

  • PEF monitoring is most commonly used
    • Best of 3 forced blows recorded twice daily for 2 weeks
    • Greater than 20% variability in readings
    • Improvement of greater than 20% with salbutamol, Inhaled Cortico Steroid for 6 weeks or oral prednisolone for 14 days

To calculate variability:

  • subtract the lowest reading from the highest
  • divide by the highest reading and multiply by 100
  • e.g. 450 (highest reading) – 360 (lowest reading) = 90 (variation) 90 ÷ 450 x 100 = 20% variability

Tests for eosinophilic airways inflammation

  • Fractional exhaled nitric oxide: Currently not widely available in primary or secondary care requires referral
  • Blood eosinophilia, IgE and skin prick testing: Blood eosinophilia >4%, raised allergen specific immunoglobulin E or positive skin prick tests increase the probability of asthma


  • Inhaled corticosteroids are the recommended preventer drug for adults and children for achieving overall treatment goals.
  • Goals of asthma therapy are to achieve complete control of Asthma Symptoms:
    • Maximise asthma control
      • no daytime symptoms
      • no night-time awakening due to asthma
      • no need for rescue medication
      • no limitations on activity including exercise
      • normal lung function
      • No exacerbation
      • Minimise treatment side effects


Referral Criteria

Refer to secondary:

  • Red Flags
  • Referral for tests not available in primary care
  • Diagnosis unclear
  • Suspected occupational asthma (symptoms that improve when patient is not at work, adult onset asthma and workers in high-risk occupations, worsening since change in work)
  • Poor response to asthma treatment
  • Following severe/life-threatening asthma attack

Referral Instructions

  • e-Consultation is available for this specialty
  • Referrals should be made via ICG to TRISH (if training has been undertaken) - See user guides (EMIS & S1) for further information.
  • For those Practices who have not received ICG training referrals should be made via eRS
  • Please identify speciality and clinic type

Supporting Information

Shared Decision Making

  • Patients have a right to make decisions about their care and should be fully informed about the options they face. They should be provided with reliable evidence-based information on the likely benefits and harms of interventions or actions, including any uncertainties and risks, eliciting their preferences and supporting implementation. Please support the development of a personalised Asthma Control Plan to support shared decision making and self care

Patient information/Public Health/Self Care

Evidence/Additional Information

Assurance & Governance

  • This guidance was developed on: 03.2017
  • This guidance was ratified by: The OSCAR Assurance Group
  • Date ratified: 08.2017
  • Publication Date: 08.2017
  • Review Date: 03.2019
  • Ref No: RS11 - 03.2017
Any feedback or suggestions to improve this guidance should be sent to:
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