Diagnostic performance of serum high-sensitivity procalcitonin and serum C-reactive protein tests for detecting bacterial infection in febrile neutropenia

Although a few prospective studies have addressed the question as to which biomarker of infection in adult patients with febrile neutropenia (FN) is superior, procalcitonin (PCT) or C-reactive protein (CRP), the results have been inconsistent and inconclusive. This was possibly due to the poor sensitivity of previous PCT tests that have a functional sensitivity of 0.5 ng/ml. Between November 2010 and February 2012, we prospectively compared the diagnostic utility of serum high-sensitivity (hs) PCT (lower limit of detection, 0.02 ng/ml) and CRP levels for detecting bacterial infection in patients with FN. Serum was collected within 72 h after the onset of FN in patients with hematological disorders. Seventy-five febrile episodes were evaluable. The areas under the receiver operating characteristic curves for life-threatening infection defined as septic shock and bacteremia caused by non-coagulase negative staphylococcus were 0.824 (95 % CI 0.711-0.937; P = 0.001) for hsPCT and 0.673 (0.505-0.842; P = 0.068) for CRP, respectively. In contrast, CRP, but not hsPCT, tended to increase significantly with the clinical severity, as indicated by the diagnostic classification (P = 0.002 for trend). The serum hsPCT test may be more useful than the serum CRP test in the detection of life-threatening infection at an early phase after the onset of FN. In contrast, the serum CRP test may be more useful in diagnosing the severity of infection. However, neither of these tests was able to differentiate the cause of FN with a low probability of fatal outcome.