Background:Sepsis-3 definitions have been published recently;however,their diagnostic value remains controversial.This study was to assess the accuracy of Sepsis-3 definitions compared to Sepsis-1 definitions by stratifying mortality among adult critically ill patients with suspected infection.Methods:A multicenter,prospective cohort study was conducted from November 10,2017 to October 10,2018,in five Intensive Care Units (ICUs) at four teaching hospitals.Thirty-day mortality was compared across categories for both Sepsis-3 definitions and Sepsis-1 definitions,which were evaluated by logistic regression analysis followed by measurement of the area under the receiver operating characteristic curve (AUROC) for predicting 30-day mortality rates.Results:Of the 749 enrolled patients,644 (85.9％) were diagnosed with sepsis according to the Sepsis-1 definitions.Among those patients,362 were diagnosed with septic shock (362/749,48.3％).However,according to the Sepsis-3 definitions,there were 483 patients with a diagnosis of sepsis (483/749,64.5％),among whom 299 patients were diagnosed with septic shock (299/749,39.9％).According to the Sepsis-3 definitions,sepsis (sepsis and septic shock) patients had higher 30-day mortality (41.8％) than sepsis patients according to the Sepsis-1 definitions (31.8％,x2=5.552,P =0.020).The AUROC of systemic inflammatory response syndrome (SIRS) and quick sequential organ failure assessment (qSOFA) scores with regard to 30-day mortality rates were 0.609 (0.566-0.652) and 0.694 (0.654-0.733),respectively.However,the AUROC of SOFA scores (0.828 [0.795-0.862]) were significantly higher than that of SIRS or qSOFA scores (P ＜ 0.001).Conclusion:In adult critically ill patients with suspected infection,the Sepsis-3 definitions were relatively accurate in stratifying mortality and were superior to the Sepsis-1 definitions.