The Utility of Serum Procalcitonin in Distinguishing Systemic Inflammatory Response Syndrome from Infection After Aneurysmal Subarachnoid Hemorrhage

Systemic inflammatory response syndrome (SIRS) occurs frequently after aneurysmal subarachnoid hemorrhage (aSAH). It is a clinical challenge to distinguish between SIRS and incipient infection. Procalcitonin (PCT) has been studied among general critical care patients as a biomarker for infection. We hypothesized that PCT could be useful to distinguish SIRS from sepsis in aSAH patients. Prospective, observational study conducted in the multidisciplinary intensive care unit at Mayo Clinic, Jacksonville, FL between August 2009 and September 2010. Main predictor was serum PCT obtained on admission and with subsequent episodes of SIRS. A level of 0.2 ng/mL or higher was considered as elevated PCT. Main outcome was clinical infection, which was subsequently subcategorized into major (systemic) and minor (localized) infections in the sensitivity analysis. Forty consecutive patients were enrolled. Majority (88 %) developed SIRS during the hospitalization. Infection developed in 16 (40 %) patients, with 6 patients meeting criteria for major infection. Overall, PCT was found to be highly specific for all infections and the subcategory of major infections (97 and 93 %, respectively) with related high negative predictive values. Odds ratio for elevated PCT with clinical infections ranged from 25.2 (95 % CI 2.7-233) to 33.3 (95 % CI 4.3-261) for all and major infections, respectively. Related receiver operating characteristic curves for elevated PCT were 0.74 and 0.96 for all and major infections, respectively. Procalcitonin of 0.2 ng/mL or greater was demonstrated to be very specific for sepsis among patients with aSAH. Further studies should validate this result and establish its clinical applicability.