Presepsin at the first neonatal sepsis work-up: an AUC of 0.62 is not a rule-out test

In a prospective single-center study of 150 suspected-sepsis events, presepsin separated culture-confirmed sepsis poorly at the initial assessment (AUC 0.62, 95% CI 0.48–0.76). Its cohort-derived cutoff traded 73% sensitivity for only 42% specificity; CRP discriminated better here, but neither marker can carry the sepsis decision alone.

The new marker did not sharpen the first decision

Presepsin has an appealing biological story: bacterial stimulation releases a soluble CD14 subtype that might rise early enough to help at the moment neonatal sepsis is suspected. In this prospective study, however, the first sample produced weak discrimination. Among 150 suspected-sepsis events, the area under the ROC curve was 0.62 (95% CI 0.48–0.76) for presepsin and 0.77 (95% CI 0.68–0.86) for C-reactive protein (CRP).

Novelty is not diagnostic utility. At the bedside, the useful question is whether a result separates infected from uninfected infants well enough to change a decision safely.

What the investigators actually tested

The team prospectively enrolled term and preterm newborns with suspected early- or late-onset sepsis in one Buenos Aires NICU from September 2016 through August 2018. Blood was collected at the initial medical evaluation, before antibiotics. Presepsin was stored and tested later; its results were unavailable to treating neonatologists. Confirmed sepsis required systemic inflammatory signs plus a positive blood or cerebrospinal-fluid culture. Clinical sepsis meant compatible illness and laboratory findings, negative cultures, and seven days of antibiotics.