Simple Blood Test for C-Reactive Protein May Guide Antibiotic Use in COPD Flares

A finger-prick blood test could help guide antibiotic prescriptions for people with chronic obstructive pulmonary disease (COPD) during a flare-up, avoiding unnecessary use of antibiotics, a clinical trial shows.

This simple test detects C-reactive protein (CRP), a blood marker of inflammation and bacterial infections, and resulted in 20% fewer patients using antibiotics for acute exacerbations in the trial.

Importantly, patients’ reduced use of antibiotics seemed safe, without negative effects on recovery. Safely lowering reliance on antibiotics may also contribute to lesser resistance to these medications.

The study was funded by the U.K.’s National Institute for Health Research (NIHR), and led by researchers from Cardiff University in Wales, and University of Oxford and King’s College London in England.

Findings were described in the report “C-Reactive Protein Testing to Guide Antibiotic Prescribing for COPD Exacerbations,” published in the New England Journal of Medicine.

COPD patients often experience exacerbations, or flare-ups, and when this happens, three out of four are prescribed antibiotics. But use of this medication often offers no benefit, because about two-thirds of the flares are not caused by bacterial infections.

“Governments, commissioners, clinicians, and patients living with COPD around the world are urgently seeking tools to help them know when it is safe to withhold antibiotics and focus on treating flare-ups with other treatments,” Nick Francis, PhD, a professor at Cardiff University and the study’s senior author, said in a press release.

Researchers investigated if a simple point-of-care blood test could help doctors decide whether to prescribe antibiotics to patients with COPD flares. They developed a finger-prick test that measures the amount of CRP — a marker of inflammation that rises rapidly in the blood in response to inflammatory conditions, including bacterial infections.

The idea was that people with a COPD flare and a low CRP level likely would not have an airway infection caused by bacteria, and thus would benefit little from taking antibiotics.

To determine their test’s value, the team ran an open-label trial called PACE (ISRCTN24346473), which enrolled 653 COPD patients who consulted a doctor at centers in England and Wales for an acute exacerbation. Participants were randomly assigned to either usual care guided by a CRP finger-prick test, or usual care alone.

Results showed that fewer patients taking the test used antibiotics, compared with the usual care group (57.0% vs. 77.4%). But this did not seem to happen at the expense of patient’s well-being and quality of care.

Two weeks after the consultation, the test-guided group scored better in health-related quality of life as measured by the clinical COPD questionnaire. Likewise, patients reported no negative effect on their well-being or use of healthcare services over the following six months.

“Most antibiotics are prescribed in primary medical care, and many of these prescriptions do not benefit patients: point of care testing is being vigorously promoted as a critical solution for better targeted antibiotic prescribing. However, there have been virtually no trials of point of care tests that measure impact on clinician behavior, patient behavior, and patient outcomes,” Chris Butler, a professor at University of Oxford and the study’s lead author, said.

“Ours is the first trial of biomarker guided management of AECOPD [acute exacerbations in COPD] in ambulatory care, and has found an effect that should be practice-changing,” Butler noted.

According to Francis, the finger-prick blood test assessing CRP was “able to achieve a reduction in antibiotic use that is about twice the magnitude of that achieved by most other antimicrobial stewardship interventions, and demonstrate that this approach was safe.”

“CRP-guided prescribing of antibiotics for exacerbations of COPD in primary care clinics resulted in a lower percentage of patients who reported antibiotic use and who received antibiotic prescriptions from clinicians, with no evidence of harm,” the study concluded.

Jonathan Bidmead, a patient in the PACE study, added that many people are indeed saved by antibiotics, “but also that many are harmed though unnecessary antibiotic use.”