NEW YORK  - Procalcitonin testing can reduce the length of antibiotic treatment for patients with suspected community-acquired pneumonia, mainly by permitting tailored treatment and earlier discontinuation of antibiotics, new findings indicate.
Circulating levels of procalcitonin are elevated in bacterial infections and its dynamics have prognostic implications, note Dr. Beat Muller from University Hospital Basel, Switzerland and colleagues in the first issue for July of the American Journal of Respiratory and Critical Care Medicine.
In a previous study, the investigators showed that procalcitonin testing was useful in differentiating lower respiratory tract infections that require antibiotic therapy from infections that do not.
In the current study, using a sensitive rapid assay for procalcitonin, the team evaluated the ability of procalcitonin to guide initiation and duration of antibiotic therapy in 302 consecutive patients with suspected CAP. The patients had similar clinical, laboratory, and microbiology characteristics, and Pneumonia Severity Index scores at baseline.
Half of the patients received antibiotics according to usual practice (the control group), while the other half received antibiotic therapy based on serum procalcitonin levels.
Antibiotics were strongly discouraged if the procalcitonin level was 0.1 µg/L or lower; discouraged for levels lower than 0.25 µg/L; encouraged for levels greater than 0.25 µg/L; and strongly encouraged for levels greater than 0.5 µg/L.Antibiotics were withheld on admission in 15% of patients in the procalcitonin group due to very low procalcitonin levels, consistent with the absence of bacterial infection. According to the team, procalcitonin guidance significantly reduced total antibiotic exposure, "mainly by individually reducing the duration of antibiotic courses from a median of 12 days to 5 days."
Supporting the safety of procalcitonin-guided antibiotic therapy, clinical and laboratory outcomes were similar between the groups; the overall success rate was 83%. In an editorial, Dr. Richard G. Wunderink of Northwestern University in Chicago notes that the "major finding" in this study was the ability of procalcitonin testing to decrease the duration of antibiotic therapy. "No other secondary variables, including hospital length of stay and mortality, were different when therapy was based on procalcitonin levels," he notes.
However, 14-day treatment of CAP is no longer the standard, Dr. Wunderink points out, noting that newer guidelines recommend 7 days or less of antibiotics. Therefore, the use of procalcitonin-guided therapy is unlikely to have a major impact, if current guidelines are followed.
"The major implication of this study," Dr. Wunderink writes, "is to support putting a cap on the duration of antibiotic therapy for CAP, similar to that of ventilator-associated pneumonia."
The greatest clinical benefit of procalcitonin-directed therapy," he adds, "still appears to be in the selection of patients who may not need antibiotics at all, or at least, not beta-lactam antibiotics."