BackgroundThe assessment of critically ill patients is often a challenge for clinicians. There are a number of scoring systems such as Acute Physiology and Chronic Health Evaluation II (APACHE II), Sequential Organ Failure Assessment (SOFA) and C-reactive protein test (CRP), which have been shown to correlate with outcome in a variety of Intensive Care Unit (ICU) patients. Therefore, use of repeated measures of these preexisting scores over time is a reasonable attempt to assess the severity of organ dysfunction and predict outcome in critically ill patients. Several reports suggest that the neutrophil is a useful marker of sepsis. However, since both a large number and a small number of neutrophils indicate a severe situation, neutrophil count is difficult to use to directly predict patients’. The hypothesisWe proposed a novel scoring system identify predictive factors using a simple blood cell count that may be associated with mortality in ICU patients. Our novel scoring system (n-score) was calculated as follows: ranges of neutrophils of 0–4999cells/mm3 and 5000–9999cells/mm3 were defined as 3 and 1 points, respectively. When the neutrophil count was over 10,000cells/mm3, the score was calculated by dividing the number of cells by 10,000. Then, 1 or 2 points were added when patients were female or male, respectively. We hypothesize that n-score may be a simple and easy scoring system to estimate mortality of the patients with sepsis and severe sepsis/septic shock without requirement of special methods or special measuring equipment, and may be as reliable as the APACHE II score or SOFA score. Evaluation of the hypothesisThe retrospective evaluation was conducted at the Department of Emergency, Disaster and Critical Care Medicine at the Hyogo College of Medicine. Seventy-seven patients who were admitted to the emergency center and diagnosed sepsis or severe sepsis/septic shock between June 2007 and December 2012 and gave informed consent were enrolled. The n-score was significantly higher in non-survivors of sepsis and severe sepsis/septic shock (p<0.01, t-test) than in survivors. The ROC curve showed a sensitivity of 61.5% and a specificity of 80.4% at an n-score of 3.8 points; the area under the curve was 0.736. In addition, n-score correlated with APACHE II score (p<0.01, R=0.378) and SOFA score (p<0.05, R=0.256) on admission. ConclusionBased on these preliminary evaluations, we hypothesize that n-score may be a useful scoring system to detect risk of death in sepsis and severe sepsis/septic shock.