566 - Diagnostic Accuracy of Early-Onset Bacterial Infection Using a Serum Procalcitonin Reference Curve in Extremely Preterm Infants

Publication Number: 566.4382

Hidetoshi Go, Nihon University School of Medicine, Itabashi, Tokyo, Japan; Nobuhiko Nagano, Department of Pediatrics and Child Health, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan; Imaizumi Takayuki, nihon univercity, itabashi-ku, Tokyo, Japan; Midori Hijikata, Department of Pediatrics and Child Health, Nihon University School of Medicine, Itabashi-ku, Tokyo, Japan; Kazumasa Fuwa, Nihon University, Nerima-ku, Tokyo, Japan; Aya Okahashi, Nihon university school of medicine, Itabashi-ku, Tokyo, Japan; Ichiro Morioka, Nihon University School of Medicine, Itabashi, Tokyo, Japan

Background: Serum procalcitonin (PCT) levels vary physiologically in neonates. To address this variability, a serum PCT reference curve has been reported (Sci Rep 2016). We have previously demonstrated that the 95th percentile value of this reference curve is useful for diagnosing early-onset bacterial infection (EOBI) in preterm infants (Diagnostics 2020). However, in clinical practice, serum PCT levels in extremely preterm infants without EOBI often deviate from the 95th percentile.

Objective: This study aimed to compare serum PCT levels and the diagnostic accuracy of the serum PCT reference curve for diagnosing EOBI between extremely preterm infants (22–27 weeks gestational age [GA] at birth) and preterm infants (28–36 weeks GA at birth).

Design/Methods: This prospective study involved preterm infants admitted to our neonatal intensive care unit between March 2020 and October 2024 whose serum PCT levels were measured at birth. The infants were divided into two groups: extremely preterm and preterm infants. We evaluated serum PCT levels and the incidence of EOBI. We validated the diagnostic accuracy of EOBI using the 95th percentile value of the serum PCT reference curve, including the sensitivity, specificity, and Youden index. EOBI was diagnosed when pathogens were detected in blood cultures, nasopharyngeal swabs, stool, or intragastric amniotic fluid cultures, in addition to three or more of the following findings: respiratory, circulatory, and neurologic symptoms; abnormal body temperature and skin color; or delayed capillary filling time.

Results: In total, 698 infants were included: 57 (8.2%) in the extremely preterm group and 641 (91.8%) in the preterm group. The median serum PCT level was 0.19 ng/mL overall, 0.69 ng/mL in the extremely preterm group, and 0.17 ng/mL in the preterm group (p < 0.01; Table 1). EOBI was identified in 13 infants (1.9%), with 6 (11%) in the extremely preterm group and 7 (1.1%) in the preterm group (p < 0.01; Table 1). The diagnostic accuracy of using the 95th percentile value of the PCT reference curve for EOBI was as follows: in the extremely preterm group, the sensitivity was 83.3%, specificity was 78.4%, and Youden index was 0.617; in the preterm group, the sensitivity was 100%, specificity was 95.6%, and Youden index was 0.96 (Table 2).

Conclusion(s): Extremely preterm infants exhibited higher serum PCT levels compared to preterm infants. Furthermore, the diagnostic accuracy for EOBI using the 95th percentile of the serum PCT reference curve was lower in the extremely preterm group.

Table 1. Neonatal backgrounds.
Values are presented as the median (range) or number (percentage).
* Data were compared using Mann–Whiney U test.
** Data were compared using Pearson’s chi-square test.
BW, body weight; CRP, C-reactive protein; EOBI, early-onset bacterial infection; GA, gestational age; IgM, immunoglobulin M; PCT, procalcitonin; WBC, white blood cell

Table 2. Diagnostic accuracy of early-onset bacterial infection using the 95th percentile value of the serum procalcitonin reference curve.