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Beta2 agonist reversibility testing in COPD diagnosis

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Routine reversibility testing was previously not recommended unless there is diagnostic doubt, or the patient is thought to have both COPD and asthma (1,2,3).

  • NICE suggests that routine reversibility testing is now unnecessary in patients with a convincing history and examination compatible with COPD, and it may even be misleading (2)
    • repeated FEV1 measurements can show small spontaneous fluctuations
    • results of reversibility test performed on different occasions can be inconsistent and not reproducible
    • over-reliance on a single reversibility test may be misleading unless the change in FEV1 is greater than 400ml
    • definition of the magnitude of a significant change is purely arbitrary
    • asthma and COPD can usually be distinguished on the basis of history and examination. In certain circumstances, where diagnostic doubt remains, or where the patient is thought to have both COPD and asthma, reversibility testing or serial PEF rate measurements should be carried out
      • asthma is suggested if there is
        • a large (>400ml) FEV1 response to bronchodilators
        • a large (>400ml) FEV1 response to 30mg oral prednisolone daily for two weeks
        • serial PEFR measurements showing 20% or greater diurnal or day-to-day variability
  • NICE have now suggested that post-bronchodilator spirometry should be measured to confirm the diagnosis of COPD. The use of post-bronchilator spirometry is used in the updated classification of COPD (2):
  • Assessment and classification of severity of airflow obstruction
    The severity of airflow obstruction should be assessed according to the reduction in FEV1 as shown in table

Post-bronchodilator FEV1/FVC

FEV1 % predicted

Severity of airflow obstruction

Using NICE clinical guideline 12 (2004)

Severity of airflow obstruction

Using ATS/ERS 2004

Severity of airflow obstruction

Using GOLD 2008

Severity of airflow obstruction

Using NICE clinical guideline 101 (2010)

Post-bronchodilator

Post-bronchodilator

Post-bronchodilator

< 0.7

>80%

Mild

Stage 1 - Mild Stage

Stage 1 - Mild*

< 0.7

50-79%

Mild

Moderate

Stage 2 - Moderate

Stage 2 - Moderate

< 0.7

30-49%

Moderate

Severe

Stage 3 - Severe

Stage 3 - Severe

< 0.7

< 30%

Severe

Very severe

Stage 4 - Very severe**

Stage 4 - Very severe **

*Symptoms should be present to diagnose COPD in people with mild airflow obstruction

**Or FEV1 < 50% with respiratory failure.

  • consider alternative diagnoses or investigations in:
    • older people without typical symptoms of COPD where the FEV1/FVC ratio is < 0.7
    • younger people with symptoms of COPD where the FEV1/FVC ratio is >0.7

FEV1 should be measured either:

  • before and 15 mins after nebulised terbutaline (5-10mg) or salbutamol (2.5-5mg),
  • before and 30 minutes after nebulised ipratropium bromide (500 micrograms)

Notes:

  • in the UK, the GMS contract for GPs stipulates that, in order to make a diagnosis of COPD and to exclude asthma, the patient should be shown to have an FEV1 below 70% of predicted normal, an FEV1/FVC ratio below 70% and a less than 15% response to a reversibility test (3)
  • before beta2 agonist reversibility testing, patients must be clinically stable and should avoid taking short-acting beta2 agonists for 6 hours before the test; long-acting beta2 agonists for 12 hours before the test; and long-acting anticholinergics and sustained-release theophylline for 24 hours before the test (3)
  • asthma and COPD often co-exist, but clinically significant COPD is not present if the FEV1 and FEV1/FVC ratio return to normal with drug therapy (1)
  • with respect to reversibility testing (1)
    • the FEV1 threshold has been increased from that previously recommended in the 1997 BTS COPD Guideline, which stated that an FEV1 increase >200ml and 15% of the baseline value showed reversibility
      • threshold was increased to overcome the large variability in FEV1 response that is seen from day to day - however, looking for such large changes in FEV1 may not identify people with a dual diagnosis of asthma and COPD
    • note that the 2005 British Asthma Guidelines produced by the BTS and the Scottish Intercollegiate Guidelines Network (SIGN) advocates an increase of >200ml in FEV1 and 15% of the baseline value as one of the objective methods to diagnose asthma - however, these guidelines do not deal specifically with the differentiation of asthma from COPD

Reference:


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