Predicting in-hospital mortality in infective endocarditis: insights from complete blood count parameters and NT-proBNP
Authors: Morawiec R , Misiewicz A , Bollin P , Matuszewska-Brycht O , Maeser P , Kosny M , Krejca M , Drozdz J 
Published: May 2024

Abstract

Funding Acknowledgements
None.

Introduction
Infective endocarditis (IE) is a rare condition with an increasing incidence rate and complexity of cases over the last few years, accompanied by a high mortality rate ranging from 18% to 25%. Recent studies have shown the utility of new outcome predictors based on complete blood count (CBC), such as red blood cell distribution width (RDW) and neutrophils/lymphocytes ratio (NLR). Drawing retrospectively from an 8-year experience, we provide a perspective from a tertiary center on predictors of in-hospital mortality based on basic laboratory test results in patients with valve-related IE.

Purpose
The aim of the study was to assess the clinical accuracy of CBC-based parameters as in-hospital mortality predictors.

Methods
From a tertiary center database (serving a stable population of 2.5 million citizens), we selected all patients hospitalized due to valve-related infective endocarditis between 2015 and 2022. We analyzed clinical data (including sex, age, IE localization, and etiological factors, number of cases, management and mortality), laboratory test results at admission (including CBC parameters, C-reactive protein - CRP, procalcitonin - PCT, N-terminal prohormone of brain natriuretic peptide - NT-proBNP, estimated glomerular filtration rate - eGFR, Creatinine - Crea, urea - UR). For three NT-proBNP, NLR, and RDW we provided a further analysis to compare their clinical accuracy.
Univariable logistic regression was used to assess the impact of specific factors on mortality. To determine the optimal cutoff values for predicting mortality, we analyzed the area under the curve (AUC) from receiver operating characteristic (ROC) curves and used Youden's index. P-values &lt; 0.05 were considered statistically significant.

Results
A total of 194 consecutive patients with confirmed IE were included in the study, the majority of whom were men (75.3%) with an overall median age of 62 years. The overall mortality rate was 27.8%. The most common localization was left-sided IE (92.3%). In 39.7% of cases, the etiological factor was unidentified, while Staphylococcus spp. were the most common bacteria among the identified cases. We identified significant impacts on mortality in most of the analyzed laboratory tests (RDW, platelet count, hemoglobin, NLR, PCT, NT-proBNP, eGFR, Crea, UR). Results showed that for every 1000pg/ml of NT-proBNP the risk of in-hospital death increases by 6%. ROC analysis was performed for the three parameters (RDW, NLR, and NT-proBNP), and each parameter showed an acceptable area under the curve - AUC (RDW: 0.69; NLR: 0.62; NT-proBNP: 0.78). Although we found the highest AUC for NT-proBNP (p&lt;0.001).

Conclusions
Although CBC parameters are easy to assess and useful in predicting in-hospital death in IE, the accuracy of NT-proBNP is higher. The management of IE cases requires a complex approach, and NT-proBNP, which also reflects the clinical state of patients, still remains a more useful tool.In-hospital deaths ROC analysis