Procalcitonin (PCT) is useful in predicting the bacterial origin of an acute circulatory failure in critically ill patients

Objective: To evaluate the accuracy of procalcitonin (PCT) in predicting ba cterial infection in ICU medical and surgical patients. Setting: A 10-bed m edical surgical unit. Design: PCT, C-reactive protein (CRP), interleukin 6 (IL-6) dosages were sa mpled in four groups of patients: septic shock patients (SS group), shock w ithout infection (NSS group), patients with systemic inflammatory response syndrome related to a proven bacterial infection (infect. group) and ICU pa tients without shock and without bacterial infection (control group). Resul ts: Sixty patients were studied (SS group: n = 16, NSS group, n=18, infect. group, n=16, control group, n = 10). The PCT level was higher in patients with proven bacterial infection (72 +/- 153 ng/ml vs 2.9 +/- 10 ng/ml, p = 0.0003). In patients with shock, PCT was higher when bacterial infection wa s diagnosed (89 ng/ml +/- 154 vs 4.6 ng/ mi +/- 12, p = 0.0004). Moreover, PCT was correlated with severity (SAPS: p = 0.00005, appearance of shock: p = 0.0006) and outcome (dead: 71.3 g/ml, alive: 24.0 g/ml, p = 0.006). CRP was correlated with bacterial infection (p < 10(-5)) but neither with SAPS nor with day 28 mortality. IL-6 was correlated with neither infection nor d ay 28 mortality but was correlated with SAPS. Temperature and white blood c ell count were unable to distinguish shocked patients with or without infec tion. Finally, when CRP and PCT levels were introduced simultaneously in a stepwise logistic regression model, PCT remained the unique marker of infec tion in patients with shock (PCT greater than or equal to 5 ng/ml, OR: 6.2, 95 % CI: 1.1-37, p = 0.04). Conclusion: The increase of PCT is related to the appearance and severity o f bacterial infection in ICU patients. Thus, PCT might be an interesting pa rameter for the diagnosis of bacterial infections in ICU patients.