Usefulness of the endotoxin activity assay as a biomarker to assess the severity of endotoxemia in critically ill patients

The aim of this study was to investigate the prevalence of endotoxemia in critically ill Japanese patients using the endotoxin activity assay, a newly developed rapid assay of endotoxin. The endotoxin levels (EA levels) in the blood of 314 patients admitted to our university hospital's intensive care unit (ICU) were measured within 24 h of admission, and its correlation with disease severity and outcome examined. In addition, the EA levels in 61 samples from healthy volunteers were measured. EA level was 0.39 +/- 0.25 (mean +/- SD) in patients admitted to the ICU and 0.10 +/- 0.09 in healthy controls. There was less overlap of EA level distribution between patients and controls compared with previous reports measuring EA level in mainly Caucasian populations. Our patients' EA levels were significantly correlated with disease severity criteria and 28-d mortality. When EA and procalcitonin levels were used concomitantly, disease severity could be assessed more precisely than when either marker was used alone. These results suggest that EA level is a useful marker for disease severity assessment and outcome prediction in critically ill patients.