Procalcitonin and C-reactive Protein Perform Better Than Neutrophil-Lymphocyte Count Ratio on Evaluation of Hospital Acquired Pneumonia

Abstract

Background: The relationship between biomarkers and hospital acquired pneumonia (HAP) is under studied, especially those severe cases admitted to the intensive care unit (ICU). Compared with community acquired pneumonia (CAP), HAP might have different traits regarding biomarkers due to the previous history in the hospitals. Methods: 593 adult patients were enrolled into this retrospective cohort study to determine neutrophil-lymphocyte count ratio (NLCR), procalcitonin (PCT), C-reactive protein (CRP) and serum lactate level at the admission of ICU. According to the diagnosis, patients were divided into two groups: non-infection and HAP. Discriminant analysis was performed based on better outcomes of diagnostic performance and severity evaluation. The diagnostic performance of each individual biomarker was assessed by construction of receiver operating characteristic (ROC) curves and calculation of the area under each ROC curves (AUROC). Multivariable analysis was also applied to determine most appropriate prognostic factors. Results: NLCR, PCT and CRP between non-infection and HAP group showed remarkable differences. Because of discriminant ability of severe infection, the AUROC of NLCR (0.626; 95%CI 0.581-0.671) was not comparative with conventional markers such as CRP (0.685; 95% CI 0.641-0.730) and PCT (0.661; 95% CI 0.615-0.707). Besides, AUROC of composite biomarkers, especially the combination of NLCR, CRP and WBC, were significantly greater than the single biomarkers. Conclusions: NLCR was not comparable to conventional single biomarkers such as CRP and PCT regarding to diagnosis or severity evaluation of HAP. Composite biomarkers could prompt early diagnosis and severity evaluation with improved accessibility, especially the combination of NLCR, CRP and WBC.