Point-of-Care Test Cuts Antibiotic Use in COPD Exacerbations

Troy Brown, RN

July 11, 2019

Point-of-care testing for C-reactive protein (CRP) in primary care clinics may curb unnecessary antibiotic use in patients with exacerbations of chronic obstructive pulmonary disease (COPD), data show.

"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," write Christopher C. Butler, FMedSci, Nuffield Department of Primary Care Health Sciences, University of Oxford, United Kingdom, and colleagues.

The findings were published online July 10 in New England Journal of Medicine.

CRP is an acute-phase protein that can be accurately measured at the point of care in just a few minutes and is a biomarker for assessing acute COPD exacerbations, the authors explain.

They write, "Point-of-care tests for acute infections are being promoted by government organizations, the industry, and clinical guidelines to better target antibiotic prescribing, help contain antimicrobial resistance, and improve patient outcomes.

"However, most evaluations of point-of-care tests for acute infections have solely examined analytic performance; only a few trials have evaluated the effectiveness of such tests in improving outcomes in the patients for whom the tests are intended to be used."

The researchers conducted a multicenter, open-label, randomized, controlled trial with patients who sought care at one of 86 general medical practices in England and Wales for an acute COPD exacerbation, defined as the presence of least one of the Anthonisen criteria (increased dyspnea, sputum volume, and sputum purulence). Patients in the CRP-guided group (325 patients) received usual care that was guided by CRP point-of-care testing; patients in the usual-care group (324 patients) received usual care only.

To evaluate antibiotic use and COPD-related health outcomes, the researchers used two primary endpoints: patient-reported antibiotic use for acute COPD exacerbations within 4 weeks of randomization, and COPD-related health status 2 weeks after randomization, as assessed using the Clinical COPD Questionnaire.

At 4 weeks, fewer patients in the CRP-guided group had used antibiotics than in the usual-care group (57.0% vs 77.4%; adjusted odds ratio [aOR], 0.31; 95% confidence interval [CI], 0.20 – 0.47).

"Patients who had two or three Anthonisen criteria were less likely to receive an antibiotic prescription if they were in the CRP-guided group; this finding shows that some patients who had increased sputum volume or purulence also had low CRP levels and were spared antibiotic therapy," Allan S. Brett, MD, and Majdi N. Al Hasan, MB, from the University of South Carolina School of Medicine, Columbia, write in an accompanying editorial.

On the Clinical COPD Questionnaire, the adjusted mean difference in total score at 2 weeks was –0.19 points (two-sided 90% CI, –0.33 to –0.05), which was below the prespecified boundary for noninferiority.

The authors found no significant differences in other COPD-related endpoints, such as primary care or specialist consulation, pneumonia diagnosis, or healthcare utilization during 6 months.

Two patients in the usual-care group died within 4 weeks after entering the study from causes judged to be unrelated to the study.

"In our view, the findings from this study are compelling enough to support CRP testing as an adjunctive measure to guide antibiotic use in patients with acute exacerbations of COPD. Whether primary care practices in the United States would embrace point-of-care CRP testing is another matter, given the regulatory requirements for in-office laboratory testing and uncertainty about reimbursement," Brett and Al-Hasan explain.

The editorialists say relatively few patients present to primary care practices for treatment of acute COPD exacerbations; however, point-of-care CRP testing has resulted in lower antibiotic prescribing for patients with more common clinical presentations, such as suspected lower respiratory tract infections, and therefore has the potential to be used more widely.

"One final point deserves emphasis," the editorialists stress. "[This] study only suggests a way to reduce antibiotic prescribing without compromising clinical outcomes. It does not establish which patients (if any) truly benefit from antibiotic therapy or which antibiotics are most appropriate for COPD exacerbations. Additional clinical trials will be necessary to address these uncertainties."

Alere (now Abbott) provided devices and associated training to participating general practices at no cost to the study. Butler has received personal fees from Roche Molecular Systems and grants from Roche Molecular Diagnostics. One coauthor has received grants from Abbott Diagnostics; another coauthor has received grants from Merck Sharp Dohme. The editorialists have disclosed no relevant financial relationships.

N Engl J Med. Published online July 10, 2019. Abstract, Editorial

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