Diagnostic value of procalcitonin serum levels in comparison with C-reactive protein in allogeneic stem cell transplantation

BACKGROUND AND OBJECTIVES: Infections represent the major complications following allogeneic stem cell transplantation (SCT). A promising marker for a more specific and early detection of bacterial or fungal infections is procalcitonin (PCT). DESIGN AND METHODS: Maximum values (m) and increase (Delta) of PCT and C-reactive protein (CRP) were prospectively analyzed during 214 clinical events in a cohort of 61 patients undergoing allogeneic SCT. Systemic reactions during bacterial or fungal infections were classified according to the ACCP/SCCM criteria. RESULTS: mPCT and mCRP (normal <0.5 microg/L and <5 mg/L, respectively) levels were high during bacterial and fungal infections (median 2.3 microg/L and 188 mg/L), moderately elevated during fever of unknown origin (median 1.5 microg/L and 82 mg/L) and low during clinical events for which there was no evidence of bacterial or fungal infections (median 0.4 microg/L and 55 mg/L). The area under the receiver operator characteristic (ROC) curve was 0.70 for mPCT, 0.76 for mCRP, 0.76 for DeltaPCT and 0.83 for DeltaCRP. Cut-off concentrations for optimum prediction of bacterial or fungal infection were: mPCT > 1 microg/L, mCRP > 100 mg/L, DeltaPCT > 1 microg/L and DeltaCRP > 50 mg/L. An increase of PCT during a bacterial or fungal infection was usually detected 1 day after the onset of fever, while the rise of CRP occurred 1 day before. mPCT was strongly correlated with the severity of systemic reaction during infection (sepsis vs severe sepsis/septic shock: p=0.0002). INTERPRETATION AND CONCLUSIONS: The diagnostic value of PCT was not superior to that of CRP in the detection of bacterial or fungal infections after allogeneic SCT. However, PCT assays may be useful in studies which compare the severity of infectious complications.