CRP Blood Test May Help Reduce Antibiotics Prescribed for COPD Flare-Ups

September 6, 2019

Prescriptions for COPD contribute to antimicrobial resistance.

Antibiotics have long been prescribed to treat and prevent the flare-ups associated with chronic obstructive pulmonary disease (COPD), but both their short-term remedial and long-term prophylactic use is not without some controversy. 

Although three quarters of all COPD patients receive antibiotics for a flare-up, only a third of flare-ups are actually caused by bacterial infections, which antibiotics are designed to treat. Flare-ups can also be caused by viral infections and environmental factors, such as smoking or exposure to pollution. Since antibiotic therapy is potentially associated with serious side effects, such as increasing a patient’s vulnerability to drug-resistance bacteria, the risks may sometimes outweigh any potential benefits. 

Adding a simple blood test to the diagnostic toolkit may help curb over-prescribing and limit antibiotic use. 

According to “COPD Exacerbations - A Target for Antibiotic Stewardship,” a study published in the New England Journal of Medicine (NJEM), a blood test that measures C-reactive protein (CRP) can help determine which patients might benefit from antibiotic therapy.

Thecriteria for antibiotic therapy in COPD flare-ups are increased dyspnea, sputum volume, and sputum purulence. The Global Initiative for Chronic Obstructive Lung Disease guidelines recommend the use of antibiotics in patients who meet all three of those criteria or in patients who demonstrate two criteria, if sputum purulence is one of them. 

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The NJEM study suggested that measuring the level of CRP protein in a patient’s blood can be useful. If the CRP level is lower than 20 mg per liter, antibiotics are unlikely to be beneficial. If the CRP level is higher than 40 mg per liter, there might be some benefit to antibiotic therapy.

To measure how predictable the blood tests could be in reducing antibiotic prescriptions for COPD flare-ups, the study divided patients and health care providers into groups, informing providers in one group about the importance of CRP testing and not informing providers in the other group. Health care providers who were not informed about the benefits of CRP testing tended to cautiously prescribe more antibiotics, while those who knew about the testing prescribed them less often. 

Patients diagnosed using the usual criteria (77.4%) were given antibiotics, while only 57% of the patients in the CRP-guided group received an antibiotic prescription, suggesting that CRP testing may prove helpful in reducing the over-prescribing of antibiotics in the treatment of COPD flare-ups.

Patients who are prescribed antibiotics for a COPD flare-up should always receive information about any possible side effects and be advised to report any side effects to a healthcare professional.