A randomized controlled superiority trial in France found that use of a rapid point-of-care test that can help clinicians determine who might benefit from antibiotics did not reduce antibiotic prescribing for children or adults with suspected respiratory tract infections (RTIs).
The findings were published yesterday in Clinical Microbiology and Infection.
Distinguishing between viral and bacterial infections
Respiratory infections are one of the primary indications for antibiotic prescribing in outpatient settings in France and other countries, though antibiotics are often unnecessary because RTIs are frequently caused by viruses. While patients with bacterial infections benefit from antibiotics, unnecessary antibiotic prescribing for viral RTIs contributes to antibiotic resistance and can lead to adverse events.
Point-of-care testing for C-reactive protein (CRP POCT) is one of the tools clinicians can use to differentiate between a viral and bacterial infections. CRP is a biomarker for inflammation found in previous studies to reduce antibiotic prescribing for non-severe respiratory infections.
The trial, conducted in the offices of 26 general practitioners (GPs) in Paris from October 2019 to March 2023, assigned 207 patients ages 3 and older with clinically suspected RTIs to receive CRP POCT. GP's in the CRP POCT group used a finger-prick blood test that can return results within 2 minutes and were given antibiotic prescribing guidance based on CRP levels, but were free to prescribe treatments according to their clinical judgement.
A control group of 197 patients was not tested for CRP levels.
The primary endpoint of the trial was the rate of antibiotic prescribing in both groups. Secondary outcomes were rates of prescribing for specific age brackets: 3 to 17 (children), 18 to 64 (adults), and age 65 and older (elderly patients).
To prove superiority, investigators targeted a 15% reduction in antibiotic prescribing for the CRP POCT group.
The results, however, showed that antibiotic prescribing rates were similar in both groups. A total of 183 patients were prescribed antibiotics by their GPs — 89 of 207 patients (43%) in the CRP POCT group compared with 94 of 197 (47.4%) in the control group (difference, –4.7 percentage points; 95% confidence interval [CI], –14.4 to 5.0).
The antibiotic-prescribing rates in the age brackets of 3 to 17 years, 18 to 64 years, and 65 years and older were respectively 20%, 37.6%, and 65% in the CRP POCT group and 21.9%, 43.9%, and 72.5% in the control group (difference, –1.9, –6.3, and –7.5 percentage points, respectively). Overall, 75% of the GPs in the CRP POCT group followed the CRP-based antibiotic recommendations.
"This randomized study conducted among GPs does not confirm the utility of CRP POCT at doctors' offices for deciding whether to prescribe antibiotics," the study authors wrote.
Other measures of utility
The authors note that while the findings conflict with previous studies of CRP testing, the results could be explained by the fact all GPs in the study had been trained in appropriate antibiotic prescribing, and the study only included patients with clinically suspected lower respiratory tract infections (LRTIs), as opposed to all patients with respiratory symptoms.
This randomized study conducted among GPs does not confirm the utility of CRP POCT at doctors' offices for deciding whether to prescribe antibiotics.
They also suggest reduced antibiotic prescribing is not the only way to measure the utility of CRP testing in outpatient settings. It can also ensure that antibiotic prescribing is "well founded," they say. For example, patients with high CRP levels in the trial were nearly all prescribed antibiotics, either for immediate use or later use if their symptoms failed to subside.
"These patients, who make up a minority (about 18% in this study) of those consulting for respiratory symptoms, are at risk for bacterial LRTIs that require antibiotic treatment," they wrote. "A failure to prescribe antibiotics in such cases can lead to serious complications."
The authors said future research should investigate if a combination of antibiotic stewardship training, CRP POCT, rapid diagnostic tests for viral respiratory infections, and lung ultrasounds could more reliably detect bacterial RTIs.
