Background Encephalopathy is a common complication of sepsis,and its onset can occur at any stage of sepsis and implies worse prognosis.However,the incidence,epidemiology,and pathogenesis of sepsis-associated encephalopathy remain controversial.The purpose of this study was to investigate the epidemiological features and risk factors for sepsis-associated encephalopathy.Methods Our retrospective study included all patients with sepsis admitted to our intensive care unit from 2008 to 2011.After excluding 91 patients,232 patients were assigned to either a sepsis-associated encephalopathy group or sepsis without encephalopathy group.Between-group differences in baseline patient data including vital signs,disease severity,pathogens,sites of infection,biochemical indicators,and time on a mechanical ventilator,intensive care unit (ICU) stay,and 28-day mortality rate were analyzed.Results The incidence of sepsis-associated encephalopathy was 17.7％.The sepsis-associated encephalopathy group had significantly higher 28-day mortality (56.1％ vs.35.1％; P=0.013),spent a significantly longer time on a ventilator ((8.2±2.2) days vs.(2.9±0.4) days; P=0.021),and had a significantly longer ICU stay ((12.4±2.4) days vs.(7.1±0.6) days;P=0.042).Acute physiology and chronic health evaluation Ⅱ score,Glasgow coma scale,heart rate,blood lactate,serum sodium,platelets,serum albumin,and pH values were related to the presence of encephalopathy.Patients with biliary tract infections and intestinal infections caused by Staphylococcus aureus,Enterococcus faecium,Acinetobacter spp,Pseudomonas aeruginosa,and Stenotrophomonas maltophilia,were more prone to develop sepsis-associated encephalopathy.Conclusions Encephalopathy increases mortality rate in septic patients.Clinical intervention to reduce risk factors and thereby morbidity and mortality depends on a correct understanding of the differences between patients with sepsis and patients with both sepsis and encephalopathy.