Abstract:Objective To study the value of procalcitonin (PCT) within 3 days after birth in the diagnosis of neonatal early-onset sepsis (EOS), as well as the thresholds of PCT in the diagnosis of EOS in neonates with different gestational ages and different ages. Methods A total of 109 neonates with a confirmed diagnosis of sepsis, 215 neonates with clinically diagnosed sepsis, and 367 neonates without sepsis were enrolled. Receiver operating characteristic (ROC) curves were plotted to determine the optimal cut-off values of PCT in the diagnosis of EOS in neonates with different gestational ages and different ages. The diagnostic value of PCT and blood culture was compared. Results In the confirmed diagnosis group, the neonates with a gestational age of <34 weeks had a significantly higher level of PCT than those with a gestational age of ≥34 weeks (P < 0.05). For the neonates with a gestational age of ≥34 weeks, the optimal cut-off values of PCT in the diagnosis of EOS were 1.588 ng/mL (sensitivity 0.688, specificity 0.851) at age of <12 hours, 4.960 ng/ mL (sensitivity 0.737, specificity 0.883) at age of 12-<24 hours, 5.583 ng/mL (sensitivity 0.727, specificity 0.865) at age of 24 - <36 hours, 1.710 ng/mL (sensitivity 0.732, specificity 0.755) at age of 36- <48 hours, 3.570 ng/mL (sensitivity 0.488, specificity 0.930) at age of 48-<60 hours, and 3.574 ng/mL (sensitivity 0.333, specificity 0.900) at age of 60-72 hours. PCT had a larger area under the ROC curve in the diagnosis of EOS than blood culture within 36 hours after birth (P < 0.05). Conclusions The same criteria can be used for late preterm infants (with a gestational age of ≥34 weeks) and full-term infants, while early preterm infants (with a gestational age of <34 weeks) should be considered separately. PCT has different optimal cut-off values in the diagnosis of EOS in neonates with different ages, with a higher value than blood culture in the diagnosis of EOS within 36 hours after birth.