Osteoprotegerin is Higher in Sepsis Than in Noninfectious SIRS and Predicts 30-Day Mortality of SIRS Patients in the Intensive Care

Background: Systemic inflammatory response syndrome (SIRS) is a complex disease involving multiple pathways and organs. Biomarkers reflecting these pathways and organ function could correlate with the severity of the disease. Osteoprotegerin (OPG), mainly known for its role in bone metabolism, is also involved in the immune and vascular system and is therefore an interesting biomarker to study in SIRS patients. In this prospective observational study, we investigated the correlation of plasma OPG concentrations, sepsis, and 30-day mortality of SIRS patients in the intensive care unit (ICU). Methods: This observational, single-center, cohort study included 313 consecutive patients admitted to the ICU, with an anticipated stay of more than 48 h and SIRS on admission. Data from included patients were collected daily until discharge or death for a maximum of 10 days. Thirty-day mortality was retrospectively assessed. OPG concentrations were measured in the first 48 h after admission. The relation of OPG with no sepsis, sepsis, and septic shock was assessed with the Kruskal-Wallis test and the Mann-Whitney U-test. Cox proportional hazards regression was used to study OPG concentrations and 30-day mortality. Results: OPG concentrations were higher in patients with sepsis and septic shock than in patients without sepsis. Furthermore, patients with OPG concentrations in the highest tertile at admission in the ICU have an increased risk of mortality within 30 days when compared to patients with OPG concentrations in the lowest and middle tertiles, independent of acute physiologic and chronic health evaluation (APACHE) and sequential organ failure assessment (SOFA) scores. Conclusions: Weshow that OPG is a biomarker that correlates with sepsis and predicts mortality of SIRS patients in the ICU.