Clinical Utility of Serum Procalcitonin Level and Infection in the Neurosurgical Intensive Care Unit.

BACKGROUND: Procalcitonin, a bloodstream inflammatory biomarker, has proven useful in the diagnosis of sepsis in critically ill patients treated in medical and surgical intensive care units. This study aims to further our understanding of the significance of procalcitonin levels in neuroscience intensive care unit (NICU) patients.

METHODS: Neurosurgical patients who underwent a procalcitonin assay in an NICU over a 2-year period were included in our analysis. A procalcitonin level ≥0.2 ng/mL was considered a positive result. Infection was defined by clinical and/or microbiological diagnosis. Sensitivity, specificity, positive predictive value, and negative predictive value in the diagnosis of clinically and/or microbiologically identified infection were calculated for procalcitonin level ≥0.2 ng/mL.

RESULTS: The study cohort comprised 203 patients, including 63 with a positive procalcitonin assay (31%). Meeting the criteria for SIRS was the most common reason for a procalcitonin draw (35.5%). A procalcitonin level >0.2 ng/mL was not significantly associated with infection (P = 0.25). With a 37.4% false-negative rate and a 10.8% false-positive rate, the sensitivity of a procalcitonin level >0.2 ng/mL was 35.0%, specificity was 74.4%, the positive predictive value was 65.1%, and the negative predictive value was 45.7%. A receiver operating characteristic analysis revealed an area under the curve of 0.61.

CONCLUSIONS: Although the utility of procalcitonin in sepsis and bacterial pneumonia has been amply demonstrated, this biomarker shows limited utility in diagnosing infection in our cohort, emphasizing the importance of cautious and selective use of procalcitonin assays in NICU patients.