Procalcitonin Results Fail to Guide Lower Antibiotic Use

Procalcitonin assays results did not help emergency department and hospital-based clinicians prescribe fewer antibiotics for patients presenting with suspected lower respiratory tract infection, according to a study published July 19 in the New England Journal of Medicine to coincide with its presentation at the American Thoracic Society 2018 International Conference in San Diego.

Procalcitonin is a blood-based peptide that correlates with the severity of bacterial infections. European studies have shown that procalcitonin-based guidance reduced the use of antibiotics with no apparent patient harm. However, in the United States there is no consensus among national authorities and medical societies about procalcitonin-guided antibiotic use for suspected lower respiratory tract infection.

The Procalcitonin Antibiotic Consensus Trial included 1,656 patients who presented to the emergency department at 14 U.S. hospitals (primarily urban, academic medical centers from November 2014 through May 2017) with a suspected lower respiratory tract infection. Treating physicians were uncertain whether antibiotic therapy was indicated. Participants were randomized to either the procalcitonin group (n=826), in which the treating clinicians were provided with real-time initial procalcitonin assay results (bioMérieux), or the usual-care group (n=830).

Participating clinicians retained autonomy over care decisions, but they received training regarding national antibiotic guidelines for lower respiratory tract infection and the procalcitonin antibiotic prescribing guideline. Blood samples were taken for procalcitonin measurement in the emergency department and serially if the patient was hospitalized. In the usual-care group, blood was drawn at enrollment for procalcitonin measurement using the same assay, but the results were clinically unavailable.

The researchers found, overall, 47.2 percent of patients were hospitalized, 36.5 percent received antibiotics in the emergency department, and 59.4 percent received antibiotics within 30 days. In the procalcitonin group, initial procalcitonin assay results were received 95.8 percent of patients with a median time from sample collection to assay result of 77 minutes. Yet, 16 patients left the emergency department before the results could be reported. Just over 2 percent of the patients in the usual-care group received a procalcitonin assay as part of usual care.

There was no significant difference in antibiotic exposure during the first 30 days between the procalcitonin group and the usual-care group (mean antibiotic-days, 4.2 and 4.3 days, respectively). Additionally, there was no significant difference between the groups regarding the percentage of patients receiving any antibiotics within 30 days, the percentage of patients receiving an antibiotic prescription in the emergency department, or the mean hospital antibiotic-days for hospitalized patients. The proportion of patients with adverse outcomes within 30 days was also similar between the groups, with hospital readmission the most common individual adverse outcome.

"It seems likely that physicians already commonly withheld antibiotics based on clinical signs alone, and, therefore, instead of the magic bullet I and many others hoped procalcitonin might be, it offered only limited incremental value over clinical judgment," said lead author David Huang, M.D., from University of Pittsburgh, in a statement.

Takeaway: In this large, U.S. trial, procalcitonin assays did not significantly improve antibiotic stewardship among emergency department physicians and hospital-based clinicians treating patients with suspected lower respiratory tract infections.