A simple scoring system based on neutrophil count in sepsis patients

Abstract

Background: The 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 hypothesis: We 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 0-4999 cells/mm(3) and 5000-9999 cells/mm(3) were defined as 3 and 1 points, respectively. When the neutrophil count was over 10,000 cells/mm(3), 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 hypothesis: The 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.

Conclusion: Based 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.