Evaluation of Neutrophil Lymphocyte Ratio (NLR) for Prediction of Mortality in Adult Sepsis Patients of ICU

Sepsis is defined as a life-threatening organ dysfunction where the host has a dysregulated immune response to infection. In early 1990s a consensus statement was developed by American College of Chest Physicians and the Society of Critical Care Medicine, they defined sepsis as systemic inflammatory response syndrome (SIRS) with or without positive blood culture. In 2016, Third International Consensus definitions for sepsis and septic shock were published 1.

The new consensus definition eliminated the terminology of SIRS and severe sepsis. Sepsis is considered as a life threatening organ dysfunction caused by a dysregulated host response to an infection. Sequential Organ Failure Assessment (SOFA) score was introduced. This scoring system based on organ dysfunction was used to define sepsis. Increase in SOFA score of 2 or more was considered to be diagnostic of sepsis. Septic shock is considered to be a subset of sepsis in which underlying circulatory and cellular or metabolic abnormalities are profound enough to increase mortality substantially1.

 The burden of sepsis is very high in low and middle income countries and mortality remains very high thus early diagnosis of sepsis is of utmost importance in initiating treatment in sepsis.

In sepsis a hyper inflammatory response is followed by an immunosuppressive phase during which multiple organ dysfunction develops which will lead to hospital acquired infections. Neutrophil play a critical role in protecting the body from infections. Therefore, a dramatical increase in neutrophil count has been found in severe infectious diseases, especially in sepsis. Lymphopenia (reduced lymphocyte count) due to lymphocyte apoptosis is a prominent feature of sepsis, which may account for adaptive immunodepression.

 Among various marker studied over time, the neutrophil to lymphocyte ratio (NLR) recently emerged as a good marker to predict sepsis severity. The neutrophil to lymphocyte ratio (NLR) is easy to perform, complete blood count (CBC) being one of the standard blood tests routinely performed upon admission to ICU. This ratio can be calculated from both the absolute number of neutrophils and lymphocytes, and from their relative number 2.

               Acute physiology and chronic health evaluation II (APACHE II) score is another commonly used indicator of severity of illness and prediction of mortality in ICU patients. It is commonly used in critically ill patients to predict outcome in both operative and non-operative cases 7.

 In this prospective observational study we will also study any correlation between NLR ratio and APACHE  II scoring while  predicting   mortality of sepsis patients.

Lacunae in existing knowledge:

NLR has been found to serve as a convenient prognostic marker in septic patients. Despite numerous pieces of evidence that reported the correlation between NLR and adverse outcomes of sepsis, it has remained controversial. NLR has previously been shown to predict adverse outcomes in adult oncology and stroke patients. It has also been used to predict adverse outcomes of bacterial meningitis patients in pediatric age group. Despite a large number of evidences confirmed an association between NLR and mortality, the relationship between NLR and outcomes of sepsis patient was rarely investigated. This study is planned to find whether NLR can predict mortality in adult sepsis patient of ICU.