J Korean Soc Emerg Med.  2022 Aug;33(4):338-345.

The role of neutrophil-to-lymphocyte ratio for the prediction of intensive care unit admission among community-acquired pneumonia patients, hospitalized through the emergency department

• Lee DH
• Park SY
• Park SH
• Kim SH
• Zhu J
• Choi SP
• Oh JH

Abstract

Objective
Multiple criteria have been proposed to assess the severity of community-acquired pneumonia (CAP) and predict intensive care unit (ICU) admissions. The neutrophil-to-lymphocyte ratio (NLR) is an inflammatory marker actively researched as a prognostic indicator in various infectious diseases. This study assessed the value of the NLR in predicting ICU admissions among CAP hospitalizations through the emergency department (ED).
Methods
A retrospective observational study of hospitalized patients with CAP via ED was performed from March 2017 to December 2018 using electronic medical records from a single center. By analyzing the clinical data at the initial presentation to the emergency room, the predictability of NLR on the admissions to the ICU was compared with other preexisting clinical scores, such as PSI (Pneumonia Severity Index), CURB-65 (Confusion, Uremia, Respiratory rate, Blood pressure, Age ≥ 65 years), and APACHE II (Acute Physiology and Chronic Health Evaluation II) scores.
Results
Of 599 CAP hospitalizations, 80 (13.4%) required ICU admissions. In multivariate logistic analysis, mean arterial pressure and NLR have significance in predicting ICU admission. The area of under curve (AUC) of preexisting clinical scores to predict ICU admission had a PSI of 0.70, CURB-65 of 0.58, and APACHE II score of 0.66. The AUC of the NLR model was 0.75, the highest among the preexisting scoring systems. Setting the NLR model as a reference value, the PSI and APACHE II scores showed no statistically significant difference in contrast to CURB-65, which showed less powerful predictability.
Conclusion
NLR is a simple, inexpensive, and rapidly available measurement in the ED, which can be used as a useful tool for predicting ICU admissions among patients with CAP over other preexisting clinical scores.

Keyword

Neutrophil-to-lymphocyte ratio; Pneumonia; Intensive care unit