Plasma Protein Biomarker Based Diagnostics of Outcome in Sepsis & CAP

3 interdependent aims are proposed to discover and initiate development of novel, in vitro diagnostic tests (IVD) for severe sepsis (SS) and community acquired pneumonia (CAP).

Specific Aim 1: Discovery and initial development of an IVD for early diagnosis of severe sepsis.

In patients with suspected sepsis, early, accurate identification of patients who will develop organ dysfunction (SS) is critical for effective management and positive outcome. While the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference definitions provide a clinical guide to identifying patients who have SS, we propose to develop a rapid, point-of-care (POC) IVD for early diagnosis of SS. The basis of the proposed IVD will be the measurement of several, host response, plasma proteins. When performed in patients at the earliest stage of sepsis, this test will have prognostic value, rapidly identifying patients who will have poor outcomes or complicated courses.

Availability of this IVD will enable patient selection for appropriate disposition, such as the intensive care unit (ICU), and use of medical therapies, such as early goal-directed therapy (EGDT), thereby reducing mortality and increasing effectiveness of resource allocation. A considerable literature exists of host plasma protein changes during sepsis. Furthermore, in preliminary studies measuring more than 100 host proteins in blood of over 300 patients with SS, we have identified a number of candidate biomarkers of SS. We propose to inventory, replicate and validate the utility of these biomarkers of SS, and to identify novel plasma biomarkers of SS, through literature review and a prospective clinical study employing 2 proteomic technologies (mass spectrometry and multiplexed immunoassays), mass spectrometry-based plasma metabolomics and sequencing of mRNA derived from peripheral blood lymphocytes. We intend to enroll 1200 patients with sepsis (evidence of infection and 2 or more criteria of the systemic inflammatory response syndrome, SIRS) at 3 US tertiary care hospitals and emergency departments (ED), and to monitor their course both by established clinical severity indices (Acute Physiology and Chronic Health Evaluation [APACHE II] and Pneumonia Patient Outcomes Research Team [PORT]scores, and metabolic endpoints such as lactate, base deficit and pH) and ascertainment of complicating events (such as SS, septic shock, acute renal failure (ARF), acute respiratory distress syndrome (ARDS),disseminated intravascular coagulopathy (DIC) and death). It is anticipated that approximately 60% of the patients will develop SS.

Data will be stored in an anonymized, encrypted, web-based patient registry. Bivariable analyses will be performed to identify and validate biomarker differences between groups. Furthermore, we intend to perform predictive modeling using multivariable analyses of the validated biomarkers and derive a biomarker panel and algorithm for early diagnosis of SS. The predictive value of the biomarker panel for early diagnosis of SS will be compared with established prognostic indices, such as metabolic endpoints and APACHE II score. Novel biomarkers of severe CAP will be identified by mass spectrometry of patient EDTA plasma samples. Subject to availability of multiplexed immunoassays, some of these biomarkers will be replicated by immunoassay in the same samples.