Background: Rapid detection of bacteremia is important for critically ill patients. Procalcitonin (PCT) has emerged as a marker of sepsis, but its characterization for predicting bacteremia is still unclear. This study aimed to investigate the role of change of PCT within 6 to 12 hours after new fever in predicting bacteremia.
Methods: An observational study was conducted in the ICU of our hospital from January 2009 to March 2010. Adult patients with new fever were included and grouped as bacteremia and non bacteremia group. Serum PCT concentration was measured at admission and within 6 to 12 hours after new fever (designated PCT0 and PCT1). Other results of laboratory tests and therapeutic interventions were recorded. Multivariate Logistic regression analysis was used to identify the risk factors of bacteremia. The area under the ROC curve (AUC) was constructed to evaluate the discriminative power of variables to predict bacteremia.
Results: Totally 106 patients were enrolled, 60 of whom had bacteremia and 46 did not have bacteremia,. The acute physiology and chronic health evaluation II (APACHE II) and sequential organ failure assessment (SOFA) scores were 13.1 ± 7.8 and 5.0 ± 2.2 at admission, respectively. There was no significant difference in PCT0 between the bacteremia group and nonbacteremia group; 1.27 µg/L (range, 0.10 - 33.3) vs. 0.98 µg/L (range, 0.08 - 25.7), (P = 0.157). However, the PCT1 and the rate of change of PCT were significantly higher in bacteremia group; PCT1 was 6.73 µg/L (1.13 - 120.10) vs. 1.17 µg/L (0.10 - 12.10) (P = 0.001), and the rate of change was 5.62 times (1.05 - 120.6) vs. 0.07 times (-0.03 - 0.18) (P < 0.001). The area under the ROC curve (AUC; 95% confidence interval) of the rate of change of PCT was better for predicting bacteremia than that of PCT1; 0.864 (range, 0.801 - 0.927) vs. 0.715 (range, 0.628 - 0.801), (P < 0.05). The AUCs of PCT0 and other parameters (such as WBC count, granulocyte percentage and temperature) were not significantly different (all P > 0.05). The best cut-off value for the rate of change was 3.54 times, with a sensitivity of 88.5% and a specificity of 98.0%. It was also an independent predictor of bacteremia (odds ratio 29.7, P < 0.0001) and wasn't correlated with the presence or absence of co-infection, neutropenia or immunodeficiency (P > 0.05).
Conclusion: The rate of change of PCT is useful for early detection of bacteremia during new fever and superior to the PCT absolute value and other parameters in non-selected ICU patients.