Schuetz et al review the 16 randomized controlled trials (n=4,647) testing procalcitonin-guided vs. standard care on the outcomes of antibiotic use, mortality, and infection control. Most of these studies were done in Europe; 6 were in ICU patients. Using procalcitonin reduced antibiotic use in all settings (primary care, emergency department, ICU) with no detectable differences in mortality. Arch Int Med 2011;171:1322-1331.
In a separate systematic review, Agarwal and Schwartz describe the 6 aforementioned randomized controlled trials (n=1,476) assessing the use of serum procalcitonin to guide antimicrobial decisions in the ICU. All 5 that measured duration of antibiotic therapy found a reduction of 20-38% with procalcitonin guidance. Length of stay was lower in 2 studies. There were no differences in mortality or infection relapse. Clin Infect Dis 2011;53:379-387.
Procalcitonin offers major promise in reducing the burden of excessive antimicrobial use. Is procalcitonin-guided therapy ready for broader use in the ICU and the community? At a minimum, we physicians could use guidance as to the best cutoff values to guide decision making. The general strategy in the ICU studies was to:
- Measure procalcitonin serially, and stop antibiotics when levels had fallen 80-90% or to 0.25-0.50 mcg/L.
- Antibiotic use was encouraged in general when procalcitonin was above 0.50 mcg/L, and strongly encouraged above 1.0 mcg/L.
A randomized trial showed harm from use of procalcitonin-driven antimicrobial strategies in Crit Care Med 2011, but they used 1.0 ng/mL as the cutoff to intensify therapy (not 0.5).