Neutrophil-to-Lymphocyte Ratio in Adult Community-Acquired Pneumonia Patients Correlates with Unfavorable Clinical Outcomes

BACKGROUND Despite the extensive improvement in antibiotic treatment and medical care, severe adult community-acquired pneumonia (CAP) remains as the significant cause of death worldwide. Earlier prognosis assessment and timely treatment in adult CAP patients are useful for prognosis. The neutrophil-to-lymphocyte ratio (NLR) in blood routine has a broad application possibility in assessing inflammatory reaction and prognosis. The aim of this study was to examine the relationship between NLR and inflammatory reaction and to unravel the usefulness of NLR in the assessment of clinical outcomes in adult CAP patients. METHODS This retrospective study was conducted based on adult patients with a primary diagnosis of CAP. All patients included received a routine blood test and calculated NLR. All of the measurement data were analyzed with paired t-test and the enumeration data were analyzed with χ2 test. Multivariate analysis was performed to investigate the association between predictors (age, male, CURB-65 scores, comorbidity, NLR, and other inflammatory cells in blood routine) and unfavorable outcomes of CAP (ICU admission and 30-day mortality). Receiver operating characteristic curves (ROC) were used to evaluate the sensitivity and specificity of NLR in predicting unfavorable outcomes of CAP. RESULTS One hundred fifty patients were included. Compared with favorable outcomes group, age, CURB-65 scores, WBC, neutrophil and lymphocyte counts, and NLR were elevated in unfavorable outcomes group (p < 0.05), gender and coexisting illness did not differ obviously. Multivariate logistic regression model analysis showed CURB-65 scores and NLR were independent predictors correlated with unfavorable outcomes (p < 0.05). The area under the ROC curve (AUC) of NLR was 0.81 (95% CI 0.73 to 0.89), the sensitivity was 81.00% and specificity was 72.8%. NLR is superior to CURB-65 in predicting unfavorable outcomes. NLR combined CURB-65 has better sensitivity and specificity (89.40% versus 91.30%). CONCLUSIONS NLR is a simple, cheap, and rapidly available measurement in blood routine and is associated with unfavorable clinical outcomes in adult CAP patients.