Longitudinal Measurements of Inflammatory Mediators in Patients at Risk of Sepsis in the Emergency Department

Sepsis is a complex condition with a time-dependent evolution. Longitudinal biomarker dynamics could help us to better characterise sepsis. We hypothesised that the kinetics of biomarkers are associated with sepsis and with the intensity of organ dysfunction, and may have predictive capacity for patient survival. This single-centre, prospective, observational study included adult patients presenting to the Emergency Department (ED) with suspected infection. Patients were included in the study if they had a National Early Warning Score 2 (NEWS 2) of 3 or higher. Blood samples were obtained at baseline, 4hs and 24 hs. Linear mixed models were constructed to analyse the association between biomarker concentrations over time, sepsis diagnosis and organ dysfunction severity. Joint models were used to evaluate the predictive ability of individual biomarker kinetics during the first 24 hours for in-hospital mortality Of 214 screened patients, 173 patients were analysed, and 137 (79%) developed sepsis. Linear mixed models revealed time-dependent decreases in IL10 ({beta} -0.016, 95%CI -0.028 to -0.004), IL1RN ({beta} -0.014, 95%CI -0.024 to -0.004), and IL6 ({beta} -0.012, 95%CI -0.024 to 0.00). Sepsis was associated with higher IL1RN ({beta} 0.378, 95%CI 0.153-0.603), and TNFRSF1A ({beta} 0.40, 95%CI 0.21-0.58); only models evaluating IL6 showed significant interaction between sepsis and time ({beta} -0.14, 95%CI -0.028 to 0.00). SOFA correlated with elevated IL10 ({beta} 0.048, 95%CI 0.021-0.075), IL1RN ({beta} 0.044, 95%CI 0.017-0.071), CCL2 ({beta} 0.046, 95%CI 0.021-0.071), TNFRSF1A ({beta} 0.050, 95%CI 0.030-0.070), and PCT ({beta} 2.63, 95%CI 1.32-3.93); the interaction between SOFA score and time was significant only for IL6 ({beta} -0.003, 95%CI -0.005 to -0.001). Joint survival models (adjusted for age and highest SOFA) identified IL8 (HR 0.655, 95% CrI 0.582-0.728), TNFRSF1A (HR 0.505, 95% CrI 0.419-0.682), and PCT (HR 1.004, 95% CrI 1.001-1.008) as predictors. ConclusionSepsis diagnosis and severity of organ dysfunction may be associated with higher levels and kinetic values of inflammatory biomarkers such as IL1RN and TNFRSF1A. IL6 levels showed a significant association for the interaction of time with both sepsis diagnosis and SOFA score. TNFRSF1A, IL8 and PCT dynamics were found to be associated with survival and could be useful in developing prognosis tools.