Practice Patterns and Outcomes Associated With Procalcitonin Use in Critically Ill Patients With Sepsis.

BACKGROUND.: Randomized trials support use of procalcitonin (PCT)-based algorithms to decrease duration of antibiotics for critically ill patients with sepsis. However, current use of PCT and associated outcomes in real-world clinical settings is unclear. We sought to determine PCT use in critically ill patients with sepsis in the United States and to examine associations between PCT use and clinical outcomes. METHODS.: This was a retrospective cohort study of approximately 20% of patients with sepsis hospitalized in US intensive care units. Hierarchical regression models were used to determine associations of PCT use with outcomes (antibiotic-days, incidence of Clostridium difficile infection, and in-hospital mortality). Sensitivity analyses were conducted to assess robustness of findings to different methods used to address unmeasured confounding (eg, instrumental variable, difference-in-differences analyses). RESULTS.: Among 20750 critically ill patients with sepsis in 107 hospitals with PCT available, 3769 (18%) patients had PCT levels checked; 1119 (29.7%) had serial PCT measurements. PCT use was associated with increased antibiotic-days (adjusted relative risk, 1.1; 95% confidence interval [CI], 1.15-1.18) and incidence of C. difficile (adjusted odds ratio, 1.42; 95% CI, 1.09-1.85) without a change in mortality (adjusted hazard ratio, 1.05; 95% CI, 0.93-1.19). Analysis of PCT use by instrumental variable and difference-in-difference analyses showed similar lack of antibiotic or outcome improvements associated with PCT use. CONCLUSIONS.: PCT use was not associated with improved antibiotic use or other clinical outcomes in real-world settings. Programs to improve implementation of PCT-based strategies are warranted prior to widespread adoption.