J Korean Soc Clin Toxicol.  2018 Dec;16(2):61-67. 10.22537/jksct.16.2.61.

Neutrophil-to-lymphocyte Ratio as A Predictor of Aspiration Pneumonia in Drug Intoxication Patients

  • 1Department of Emergency Medicine, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea. sunhwa9@hanmail.net
  • 2Department of Radiology, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, Korea.
  • 3Department of Emergency Medicine, Nowon Eulji Medical Center, Eulji University, Seoul, Korea.


To evaluate the association between neutrophil-to-lymphocyte ratio (NLR) and occurrence of aspiration pneumonia in drug intoxication (DI) patients in the emergency department (ED) and to evaluate the relationship between NLR and length of hospital admission/intensive care unit (ICU) admission.
A total of 466 patients diagnosed with DI in the ED from January 2016 to December 2017 were included in the analysis. The clinical and laboratory results, including NLR, were evaluated as variables. NLR was calculated as the absolute neutrophil count/absolute lymphocyte count. To evaluate the prognosis of DI, data on the development of aspiration pneumonia were obtained. Also, we evaluated the relationship between NLR and length of hospital admission and between NLR and length of ICU admission. Statistically, multivariate logistic regression analyses, receiver-operating characteristic (ROC) curve analysis, and Pearson's correlation (ρ) were performed.
Among the 466 DI patients, 86 (18.5%) developed aspiration pneumonia. Multivariate logistic regression analysis revealed NLR as an independent factor in predicting aspiration pneumonia (odds ratio, 1.7; p=0.001). NLR showed excellent predictive performance for aspiration pneumonia (areas under the ROC curves, 0.815; cut-off value, 3.47; p < 0.001) with a sensitivity of 86.0% and a specificity of 72.6%. No correlations between NLR and length of hospital admission (ρ=0.195) and between NLR and length of ICU admission (ρ=0.092) were observed.
The NLR is a simple and effective marker for predicting the occurrence of aspiration pneumonia in DI patients. Emergency physicians should be alert for aspiration pneumonia in DI patients with high NLR value (>3.47).


Aspiration pneumonia; Neutrophil-lymphocyte ratio; Drug intoxication; Predictive factor; Emergency medicine
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