Relationship of neutrophil-to-lymphocyte ratio with presence and severity of pneumonia

Abstract

Aim: Today, community-acquired pneumonia remains one of the causes of high mortality and morbidity. In this study, we aimed to demonstrate the relationship between NLR, which was found to be a marker related to the systemic inflammation in the recent studies, and PSI, CURB-65, and PIRO, which were developed to predict hospitalization, being taken to an intensive care unit, and prognosis in patients with community-acquired pneumonia, and mortality. Material and Method: 100 patients admitted to the department and intensive care unit with the diagnosis of community-acquired pneumonia were included in the study. The patients underwent physical examinations and their medical histories were taken when admitted to the hospital. The biochemistry, hemogram, arterial blood gas examinations were analyzed. Their Pneumonia Severity Index (PSI), CURB-65 (Confusion, Blood Urea Nitrogen, Respiratory Rate, Blood Pressure, Age >= 65), and PIRO (Predisposition, Infection, Response, Organ dysfunction) scores were calculated. NLR was defined as absolute neutrophil count divided by absolute lymphocyte count. Results: 67 of the patients in the department and another 33 in the intensive care unit were followed. The average age of patients followed in the intensive care unit was 75.3 +/- 10.3 and the average age of patients followed in the department was 66.8 +/- 12.5. A positive correlation was found between NLR and CURB-65, PIRO, and PSI scores (respectively: r: 0.354 p<0.001, r: 0.290 p: 0.003, r: 0.302 p: 0.002). In the ROC curve analysis, for the estimation of CURB-65 >2 score, NLR had a 6.26 predictive value (AUC: 0.762, 95% CI: 0.662-0.863, p<0,001), 76% sensitivity and 60% specificity; for the estimation of PIRO 4-5-6 score, NLR had a 6.67 predictive value (AUC: 0.687, 95% CI: 0.569-0.806, p=0.013), 67% sensitivity and 60% specificity; for the estimation of PSI score, NLR had a 5.55 predictive value (AUC: 0.637, 95% CI: 0.523-0.750, p<0,001), 62% sensitivity and % 58 specificity. Patients who died had significantly higher NLR levels in proportion to the survivors (13.5+9 vs 7.9+6.8, p=0.010). However, in the ROC curve analysis for the estimation of death, NLR was not superior to CURB, PIRO, and PSI scores. Discussion: NLR, a non-specific inflammatory marker that can be calculated quickly and easily in the routine hemogram examination, and is closely related to the scores regarding the severity of patients with CAP. Although it is not superior to the score systems in the estimation of death, it can be used for the same purpose as the score systems.