Treatment: Antibiotics and use of the CRP test

Assessing the need for antibiotics

In patients randomised to the CRP arm, you will use the results of the CRP test to help guide your treatment decision.

In patients randomised to usual care, you will have to make a clinical decision based on your best assessment of the patient and guided by NICE and GOLD guidelines.

NICE recommends the use of antibiotics in patients with a history of more purulent sputum.

GOLD recommends use of antibiotics in patients with increased sputum purulence and either increased dyspnoea or increased sputum volume.

However, in all patients the decision to prescribe antibiotics should be based on a comprehensive assessment of the likely risks and benefits given:

  • The patient’s underlying health status (COPD severity, co-morbidities, frailty)
  • Clinical features of the current exacerbation (including the severity of the exacerbation and the degree of sputum purulence).

In patients randomised to CRP, the results of the CRP test will also contribute to this assessment.

Interpretation of CRP results
CRP Result
< 20
Antibiotics are unlikely to beneficial and usually should not be prescribed.
Antibiotics may be beneficial – mainly if purulent sputum is present. You may decide to prescribe antibiotics after taking into account the patient’s underlying health status and the features of the current exacerbation.
> 40
Antibiotics are likely to be beneficial. Consider prescribing, antibiotics unless the patient is assessed as being at lower risk of, complications and unlikely to have a bacterial infection (no increased,sputum purulence and no features suggesting severe exacerbation).
Assessment of sputum purulence
  • Patient reported sputum colour is often not reliable.
  • Purulence can be increased in viral infections as well as bacterial infections
  • Try and obtain a sputum sample in order to objectively assess sputum purulence where possible.
  • Ask the patient how much the colour of their sputum has changed from its usual colour. This is particularly pertinent when it is not possible to objectively assess their sputum.
  • The CRP test is particularly useful when the presence of increased purulence is uncertain.