Objective: To evaluate procalcitonin (PCT) as a diagnostic marker of neonatal sepsis of vertical transmission and to compare the results of PCT with those of the most widely used laboratory tests for sepsis.
Patients and methods: A prospective study was conducted in 136 blood samples from 69 newborn infants admitted to a neonatal department. PCT, C-reactive protein (CRP), leukocyte count, and the immature-to-total neutrophil ratio (I/T ratio) were measured. The PCT reference range of controls from 0 to 72 hours of life was constructed, and the diagnostic efficiency of the tests was calculated, with their 95 % confidence intervals (95 % CI).
Results: This study included 35 controls, 24 neonates with noninfectious disorders, and 10 neonates with sepsis (5 with culture-proven sepsis). PCT, CRP, and the I/T ratio discriminated septic from nonseptic patients. Their areas under the ROC curve were 0.696 (p = 0.009), 0.735 (p = 0.002), and 0.703 (p = 0.006), respectively, with no statistically significant differences. The accuracy of PCT, CRP, and leukocyte count improved after 24 hours of life with areas under the ROC curve of 0.813 (p = 0.007), 0.826 (p = 0.005), and 0.841 (p = 0.003), respectively. Overall, PCT detected vertically transmitted sepsis with a sensitivity of 68.4 % (95 % CI: 46.0 %-84.6 %), specificity of 82.4 % (95 % CI: 72.2 %-89.4 %), positive likelihood ratio of 3.89 (95 % CI: 2.18 %-6.96 %), and negative likelihood ratio of 0.38 (95 % CI: 0.19 %-0.76 %), similar to those of CRP.
Conclusions: PCT may be a useful marker for the diagnosis of vertically transmitted sepsis. Studies with larger sample sizes are required to establish the accuracy of PCT.