Procalcitonin for the differential diagnosis of infectious and non-infectious systemic inflammatory response syndrome after cardiac surgery

BACKGROUND: This study was performed to assess the value of procalcitonin (PCT) for the differential diagnosis between infectious and non-infectious systemic inflammatory response syndrome (SIRS) after cardiac surgery. METHODS: Patients diagnosed with SIRS after cardiac surgery between April 1, 2011 and March 31, 2013 were retrospectively studied. A total of 142 patients with SIRS, infectious (n = 47) or non-infectious (n = 95), were included. The patients with infectious SIRS included 11 with sepsis, 12 with severe sepsis without shock, and 24 with septic shock. RESULTS: PCT, C-reactive protein (CRP), and the white blood cell (WBC) count were significantly higher in the infectious SIRS group than in the non-infectious SIRS group. PCT had the highest sensitivity and specificity for differential diagnosis, with a cut-off value for infectious SIRS of 0.47 ng/mL. PCT was more reliable than CRP in diagnosing severe sepsis without shock, but it was not useful for diagnosing septic shock. The PCT cut-off value for diagnosing severe sepsis without shock was 2.28 ng/mL. CONCLUSIONS: PCT was a useful marker for the diagnosis of infectious SIRS after cardiac surgery. The optimal PCT cut-off value for diagnosing infectious SIRS was 0.47 ng/mL.