The main sources of infections were pulmonary and abdominal(79.4%, 50/63)in 63 elderlypatients with sepsis.The incidences of positive blood cultures and deaths were 15.9%(10/63)and 66.7%(42/63), respectively.There existed significant differences in lymphocyte counts, arterial lactate levels, MA and lengths of stay in the ICU between the survival group and the death group( t=3.847, 2.153, 2.745, -3.574, respectively, all P<0.05).MA was correlated with arterial lactate, SOFA score and survival outcome( r=-0.498, -0.506, and -0.358, respectively, all P<0.05).Multivariate Logistic regressionanalysis showed that MA and arterial lactate were independent factors for the survival outcome( OR=1.626, 0.766, all P<0.05).The area under the ROC curve(AUC, 95% CI)for the combination of MA and arterial lactate was larger than that of either MA or arterial lactate alone(0.89, range 0.763-0.846; 0.58, range 0.574-0.730; 0.77, range 0.521-0.832; all P<0.05).