Objective To predict the risk of 28-day mortality in septic patients in intensive care unit (ICU) with the combination of Weighted index of comorbidities (WIC) and sepsis-related organ failure assessment (SOFA) score.Methods The clinical data of adult severe sepsis/septic shock patients in Department of Emergency Medicine of Changzheng Hospital and Department of Critical Care Medicine of Jinan Military General Hospital from October 2011 to February 2013 were analyzed retrospectively.The etiological factor,past history,having severe sepsis or not were recorded.Age score,WIC score,acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score and SOFA score were calculated at or 24 hours after admission.The logistic regression was used and the receiver operating characteristic curve (ROC curve) was drawn to calculate the patients' outcome.Results In 310 enrolled patients,223 (71.9％) patients survived and 87 (28.1％) died.Univariate analysis showed that the P values of the age score,WIC score,APACHE Ⅱ score and SOFA score,chronic cardiac insufficiency,type 2 diabetes,cerebrovascular disease,tumor,multiple injury,pulmonary infection and having severe sepsis or not were all less than 0.2.The above 11 variables were put into the multivariate logistic regression equation 1,of which predicted probability was reserved.It revealed that 5 variables were independently associated with 28-day prognosis,of which influence power in descending order were SOFA score [odds ratio (OR) =1.308,95％ confidence interval (95％ CI):1.158-1.478,P=0.000],having severe sepsis or not (OR =0.206,95％ CI:0.100-0.424,P=0.000),APACHE Ⅱ score (OR =1.090,95％CI:1.021-1.164,P=0.010),WICscore (OR=1.441,95％CI:1.067-1.947,P=0.017),agescore (OR=1.228,95％CI:1.027-1.468,P=0).024),the Walswere 18.554,18.369,6.725,5.662,5.067,respectively.The 3 variables,age score,WIC score and SOFA score,were brought into the multivariate logistic regression equation 2,of which predicted probability was reserved too.It revealed that age score (OR=1.330,95％CI:1.145-1.546,P=0.000),WIC score (OR =1.496,95％ CI:1.145-1.546,P=0.000) and SOFA score (OR =1.429,95％ CI:1.303-1.567,P=0.000),were independently associated with the septic patients' 28-day prognosis.There was no significant difference in the area under receiver operating characteristic curve (AUC) between the SOFA score and APACHE Ⅱ score (0.784 vs.0.780,Z=0.014,P=0.989).However,compared with APACHE Ⅱ score,the AUC of equation 1 (0.888) and 2 (0.851) were much more (Z=4.333,P=0.000; Z=2.669,P=0.008).Conclusion The sensitivity of 28-day prognosis by WIC score was improved greatly with the combination of SOFA score and age score.