J Korean Soc Emerg Med.  2022 Dec;33(6):565-572.

The association between the neutrophil-to-lymphocyte ratio and bacteremia in elderly patients admitted to the emergency department

• Yu JS
• Song H
• Youn CS
• Oh SH
• Lim J
• Kim SH
• Bang HJ
• Kim HJ

Abstract

Objective
Bacteremia is a common cause of increased morbidity and mortality in elderly patients, but early diagnosis and identification are complex. The neutrophil-to-lymphocyte count ratio (NLR) is suggested as a useful indicator for diagnosing bloodstream infections. This study evaluated whether the NLR at admission is associated with bloodstream infections in older patients admitted to the emergency department.
Methods
A retrospective, multicenter analysis was performed on patients admitted to the emergency department from November 2016 to February 2017. We included patients aged 65 years and older who visited the emergency department with medical problems. Baseline NLR values were measured upon admission to the emergency department. The primary outcome was a positive blood culture.
Results
A total of 1,815 patients were included in this study. The median age was 77.25±7.38 years, and bacteremia was identified in 290 older patients (15.9%). The NLR was significantly higher in the bacteremia group (15.95±22.03) than in the non-bacteremia group (8.76±8.74, P<0.001). In the multivariate logistic regression analysis, the NLR was associated with bacteremia after adjusting for confounding factors as continuous variables (odds ratio [OR], 1.033; 95% confidence interval [CI], 1.009-1.057) and categorical variables (NLR ≥10; OR, 2.018; 95% CI, 1.246-3.268). The area under the curve of the NLR was determined to be 0.667 (95% CI, 0.639-0.694).
Conclusion
These results indicate that the NLR at admission to the emergency department is associated with bloodstream infections. Early suspicion of bacteremia, by determining the initial NLR value, will help treat bacteremia in elderly patients.

Keyword

Aged; Bacteremia; Neutrophils; Lymphocytes