The Role of NLR in the Diagnosis and Prognosis of Sepsis
Condition: Sepsis; Infections
MeSH terms: Sepsis
Study type: Observational

Summary: 
      Neutrophil-lymphocyte ratio (NLR), as an inflammatory index, is cheap and easy to obtain, and
      could be widely used in hospitals at all levels. NLR is a valuable biomarker that is
      significantly correlated with the status of immune and inflammatory responses. In the past
      few years, NLR has been continuously and extensively explored in various diseases, and the
      research progress is considerable. In cardiovascular disease, NLR can predict arrhythmia and
      short - and long-term mortality in patients with acute coronary syndrome. NLR may be
      associated with heart failure and valvular heart disease. Moreover, NLR has been shown to be
      associated with respiratory diseases (such as chronic obstructive pulmonary disease), immune
      diseases (rheumatoid arthritis and systemic lupus erythematosus), and digestive diseases
      (acute appendicitis, hepatocellular carcinoma, liver fibrosis, and cirrhosis).

      Importantly, the study of NLR in sepsis has received much attention in recent years. A 2019
      meta-analysis concluded that peripheral white blood cell ratios, including NLR,
      lymphocyte-to-monocyte ratio (LMR), and platelet-to-lymphocyte ratio (PLR), are associated
      with clinical outcomes in sepsis and are useful biomarkers of infection. They recommended
      that NLR be evaluated in future hierarchical models, To clarify its relationship with NLR and
      clinical outcome and the prognostic value of NLR, it is worth mentioning that NLR has also
      been found to have the ability to predict the outcome of sepsis. It has been shown that NLR,
      together with other inflammatory parameters, might be a marker for early detection of sepsis
      in the intensive care unit. However, a large body of evidence demonstrating the association
      between NLR and adverse clinical outcomes in sepsis remains controversial. Another study
      concluded that "no association was found between NLR and 28-day in-hospital mortality in
      patients with sepsis". In addition, the reliability of NLR on admission in predicting the
      prognosis of critical illness was also lower than that of traditional markers (including CRP,
      PCT, serum lactic acid and APACHEⅡ score).

      This study aimed to retrospectively investigate the early predictive value of
      inflammation-related parameters in-hospital mortality of septic patients.
    

Detailed description: 
      Sepsis is defined as a life-threatening organ dysfunction caused by the host's malfunctioning
      response to infection, which has become one of the major problems in the world's public
      health. The development of effective biomarkers for the diagnosis of sepsis is undoubtedly
      helpful for us to timely and accurately understand the diagnosis, progression, and prognosis
      of sepsis.

      The neutrophil-to-lymphocyte ratio (NLR), as an inflammatory indicator, is inexpensive and
      easily accessible parameter and could be widely used. In severe infectious diseases,
      particularly in sepsis, a substantial increase in peripheral blood neutrophils has been
      discovered, which reflects the severity of the inflammatory response. Neutrophil reverse
      migration following the initial neutrophil infiltration into inflammatory scenarios may
      further exacerbate the increase in the peripheral blood neutrophils. Lymphocyte
      apoptosis-induced reduction of peripheral blood lymphocytes is a significant feature of
      sepsis that could lead to adaptive immunosuppression. NLR is a cheap and rapidly available
      predictor of sepsis and has shown a significant correlation with other relatively expensive
      and non-rapidly existing markers of inflammation and sepsis.

      Importantly, research on NLR in sepsis has received wide attention in recent years. NLR
      within 24 hours before intensive care unit (ICU) admission could be used as a marker for
      early diagnosis of sepsis. In addition to the diagnostic value of NLR, it is worth mentioning
      that NLR has also been found to have the ability of predicting the prognosis of sepsis. A
      meta-analysis in 2019 indicates that peripheral blood leucocyte ratios, including NLR,
      lymphocyte-to-monocyte ratio (LMR) and platelet-to-lymphocyte ratios (PLR), could be useful
      infection biomarkers and associated with clinical prognosis of sepsis. A meta-analysis in
      2020 also indicates that the higher NLR was linked to poor prognosis in patients with sepsis
      (n = 10,685) (hazard ratio (HR) = 1.75). NLR at admission is shown to be an independent
      predictor of in-hospital mortality of septic patients (n = 174). NLR, PLR and LMR can be
      useful predictors for early identification of post-percutaneous nephrolithotomy (PNL) sepsis.
      However, the exact role of NLR in the early prediction of the prognosis of septic patients
      remain controversial. No correlation was found between NLR at admission of emergency
      department and 28-day hospital mortality of septic patients. NLR at admission is less
      suitable than conventional inflammatory markers C-reactive protein (CRP) and procalcitonin
      (PCT) to detect the presence of sepsis in ICU patients. NLR at ICU admission is also less
      reliable than CRP, PCT, lactic acid and acute physiology and chronic health evaluation
      (APACHE Ⅱ) score in assessing the severity and in predicting 28-day mortality of critical
      illness.

      In this study, the investigators enrolled septic patients to determine the role of NLR in the
      early prediction of in-hospital mortality of patients with sepsis. In addition, considering
      that PLR, neutrophil percentage (NE%) and monocyte to lymphocyte ratio (MLR) have been
      confirmed to be also associated with the mortality of patients with sepsis, while
      retrospectively analyzing the role of NLR, the investigators also studied the roles of PLR,
      MLR, neutrophil percentage, and other inflammation-related parameters on the first, second,
      third, and seventh days after hospitilization in the in-hospital mortality of septic
      patients.
    

Intervention name(s): No intervention
Intervention type(s): Other
Intervention description(s): There was no intervention in the retrospective study
Observational model: Cohort
Time perspective: Retrospective
Sampling method: Non-Probability Sample
Study population: 
        Patients with confirmed sepsisc
      
Keywords: sepsis; NLR; Percentage of neutrophils; Prognosis