Utility of procalcitonin for diagnosis of bacterial infection-related systemic inflammatory response in the acute neurologic injury population

Objective: Inflammation and bacterial infection are common complicating factors in the treatment of patients with stroke. Inflammatory responses can manifest as systemic inflammatory response syndrome (SIRS), a condition with both infectious and non-infectious etiologies. Accurately identifying patients with infection-related SIRS is important for determining the correct treatment plan. Here, we investigated the use of the glycopeptide procalcitonin (PCT) as a potential biomarker for identifying patients with bacterial infections in the setting of SIRS. Patients and methods: A retrospective chart review was performed for adult patients admitted to United Hospital with an admission or discharge diagnosis of stroke for whom PCT testing was ordered between January 2011 and December 2014. Medical records were searched for the timing of PCT tests, and the previous 24 h was assessed for markers of SIRS, inflammation, and disease severity. Results: PCT levels were negatively correlated with Glasgow Coma Scale scores (p =-0.27, p < 0.0001) and glomerular filtration rates (p =-0.22, p < 0.001), but demonstrated a positive correlation with white blood cell (WBC) count (p = 0.13, p = 0.031) and creatinine levels (p = 0.33, p < 0.0001). PCT levels were significantly higher in samples that corresponded to the presence of at least one infection (p < 0.0001) and in SIRS + samples (p < 0.001). However, even with the addition of a SIRS + diagnosis, the predictive value of PCT did not reach levels that would indicate clinical utility for the identification of patients with bacterial infections. Conclusions: PCT was not a viable biomarker for distinguishing between infectious and non-infections etiologies of SIRS in acute brain injury in this population. However, our results do indicate potential utility for PCT as an indicator for the cessation of antibiotic use in acute brain injury patients with bacterial infections.