Butler CC, Gillespie D, White P et al.
C-reactive protein testing to guide antibiotic prescribing for COPD exacerbations.

New Engl J Med 2019;381:111–120.

C-reactive protein (CRP), which is released into the blood by the liver in response to infection or inflammation, can be measured with a simple blood test at the point of care (POC). Increased levels may help confirm diagnosis of bacterial infection.1 A retrospective case analysis investigating the impact of POC CRP testing on the management of respiratory tract infections resulted in a 65% reduction in antibiotic prescriptions by GPs.2 

People with COPD who experience acute exacerbations are often given antibiotics to manage their symptoms. However, antibiotics are only suitable if symptoms are associated with bacterial infection.3 One study found that around 20% of patients with acute exacerbations of COPD did not have bacterial or viral infection, and only half the patients had bacterial infection, meaning many people may be prescribed antibiotics unnecessarily.4  

NICE recommends that antibiotics should be restricted when treating COPD exacerbations in an effort to combat antimicrobial resistance.5 It suggests assessing the severity of symptoms, such as sputum colour changes and increases in volume or thickness beyond the patient’s normal day-to-day variation, to guide antibiotic prescribing.3 GOLD guidelines state the signs of bacterial infection that warrant antibiotics for exacerbations of COPD are increased dyspnoea, sputum volume and sputum purulence.6 

It is not always possible to identify which patients can be effectively treated without antibiotics with a clinical diagnosis. A recent study by Butler et al. therefore set out to determine whether CRP testing in primary care might be a way to safely reduce the use of antibiotics among patients with acute exacerbations of COPD.7 

In a multicentre, open-label, randomised, controlled trial, the authors recruited patients from 86 general practices in England and Wales who presented with an acute exacerbation of COPD, with increased breathlessness and/or increased sputum volume and/or increased sputum purulence. Patients were randomly assigned to receive usual care guided by CRP POC testing (n=325) or usual care alone (n=324). Patients were followed up at for 4 weeks.

GPs were advised to prescribe antibiotics for patients with a CRP level of 20–40mg/l in the presence of purulent sputum and for all patients with a CRP level above 40mg/l.

The study found a lower rate of antibiotic use in patients in the CRP group than in those treated with usual care (57.0% vs 77.4%, adjusted odds ratio 0.31; 95% CI 0.20 to 0.47), with no significant difference in patient-reported quality of life. The authors suggest that using CRP in general practice to guide management of acute exacerbations of COPD may therefore be a safe way to reduce the unnecessary use of antibiotics for these patients.

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