Plasma Neprilysin for Predicting Sepsis Within 48 Hours in ICU Patients With Infection or Suspected Infection

The goal of this multicenter prospective observational cohort study is to determine whether plasma neprilysin can predict the development of sepsis within 48 hours in adults admitted to an intensive care unit with confirmed or suspected infection who do not have sepsis at enrollment. The study will be conducted at Zhujiang Hospital, Southern Medical University, and Guangzhou First Municipal People's Hospital. Plasma samples remaining after routine clinical testing will be used to measure neprilysin and conventional sepsis biomarkers. Sublingual microcirculation will also be assessed when feasible. Participants will be assessed for the development of sepsis from enrollment through 48 hours and will be followed for survival through Day 28. No treatment or clinical intervention will be assigned by the study protocol.

Inclusion Criteria: * Age 18 years or older. * Confirmed or suspected infection as assessed by the treating physician based on symptoms, signs, laboratory findings, imaging findings, microbiological findings, or evidence of an infection source, with systemic antimicrobial therapy initiated or planned. * Does not meet the protocol-defined criteria for sepsis at enrollment. In the setting of confirmed or suspected infection, there must be no acute increase of 2 or more points in the Sequential Organ Failure Assessment 2 score from baseline that is attributable to infection. * Expected by the treating physician to remain in the intensive care unit for more than 48 hours after enrollment. * Written informed consent provided by the participant or the participant's legally authorized representative. Exclusion Criteria: * Sepsis diagnosed at intensive care unit admission or fulfillment of the Sepsis-3 criteria at screening. * Insufficient clinical data to determine the baseline SOFA-2 score according to the prespecified assessment criteria. * Patients with limited nursing care (patients for whom active treatment has been withdrawn) * No blood sample is available on the day of enrollment. * Considered unsuitable for participation by the investigator.