The Neutrophil-Lymphocyte Count Ratio in Patients with Community-Acquired Pneumonia

Cornelis P C De Jager,Tom Van Der Poll,Arianne B Van Gageldonk-Lafeber,Robert J F Laheij,Peter C Wever,Ron Kusters,Eugenie F A Gemen,Matthias Eberl

doi:10.1371/journal.pone.0046561

Abstract

Study ObjectiveThe neutrophil-lymphocyte count ratio (NLCR) has been identified as a predictor of bacteremia in medical emergencies. The aim of this study was to investigate the value of the NLCR in patients with community-acquired pneumonia (CAP).Methods and ResultsConsecutive adult patients were prospectively studied. Pneumonia severity (CURB-65 score), clinical characteristics, complications and outcomes were related to the NLCR and compared with C-reactive protein (CRP), neutrophil count, white blood cell (WBC) count. The study cohort consisted of 395 patients diagnosed with CAP. The mean age of the patients was 63.4±16.0 years. 87.6% (346/395) of the patients required hospital admission, 7.8% (31/395) patients were admitted to the Intensive Care Unit (ICU) and 5.8% (23/395) patients of the study cohort died. The NLCR was increased in all patients, predicted adverse medical outcome and consistently increased as the CURB-65 score advanced. NLCR levels (mean ± SD) were significantly higher in non-survivors (23.3±16.8) than in survivors (13.0±11.4). The receiver-operating characteristic (ROC) curve for NLCR predicting mortality showed an area under the curve (AUC) of 0.701. This was better than the AUC for the neutrophil count, WBC count, lymphocyte count and CRP level (0.681, 0.672, 0.630 and 0.565, respectively).ConclusionAdmission NLCR at the emergency department predicts severity and outcome of CAP with a higher prognostic accuracy as compared with traditional infection markers.

Highlights

Community-acquired pneumonia (CAP) is a common, potentially fatal disease despite advances in both diagnosis and treatment [1,2,3,4]
Neutrophilia is well recognized as infection marker whereas the clinician is less familiar with absolute lymphocytopenia
As community-acquired pneumonia (CAP) is an important reason for Emergency Department (ED) admission and subsequent hospitalization, we prospectively studied the prognostic value of neutrophil-lymphocyte count ratio (NLCR) in patients with this condition

Summary

Introduction

Community-acquired pneumonia (CAP) is a common, potentially fatal disease despite advances in both diagnosis and treatment [1,2,3,4]. New techniques are being developed, defining the microbial etiology and classifying the severity of CAP both remain challenging issues. Biomarkers, preferably in combination with clinical risk scores, are increasingly used to identify specific patients at risk, to judge the severity of illness and prognosis of CAP and more recently to guide antibiotic therapy [5,6,7,8,9]. As the allocation of resources is, important, the high prices for the use of newly developed biomarkers make their use less attractive [10]. Following endotoxemia the number of circulating neutrophils increases while lymphocyte counts decrease [11]. Neutrophilia is well recognized as infection marker whereas the clinician is less familiar with absolute lymphocytopenia

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Conclusion