title: Perioperative neutrophil to lymphocyte ratio as a predictor of poor cardiac surgery patient outcomes.
abstract: OBJECTIVE
  The purpose of the present study was to investigate the association between the perioperative neutrophil to lymphocyte ratio (NLR) and cardiac surgery patient outcomes.
  
  
  METHODS
  A retrospective cohort study of 145 patients who underwent cardiac surgery in a tertiary hospital of Athens, Greece, from January to March 2015, was conducted. By using a structured short questionnaire, this study reviewed the electronic hospital database and the medical and nursing patient records for data collection purposes. The statistical significance was two-tailed, andp-values <0.05 were considered significant. The statistical analysis was performed with Mann-WhitneyUtest and Spearman's correlation coefficient, by using the Statistical Package for Social Sciences software (IBM SPSS 21.0 for Windows).
  
  
  RESULTS
  The increased preoperative levels of NLR were associated with significantly higher mortality, both in-hospital (p=0.001) and 30-day (p=0.002), prolonged postoperative hospital length of stay (LOS), both in the cardiac intensive care unit (ICU) (p=0.002), and in-hospital (p=0.018), and likewise with delayed tracheal extubation (p≤0.001). Furthermore, patients with elevated NLR during the second postoperative day had significantly higher in-hospital mortality (p=0.018), increased incidence of pneumonia (p=0.022), higher probability of readmission to the ICU (p=0.002), prolonged ICU LOS (p≤0.001), and delayed tracheal extubation (p≤0.001).
  
  
  CONCLUSIONS
  Increased perioperative NLR seems to be associated with significantly higher mortality and morbidity in cardiac surgery patients. At the same time, NLR is a significant and inexpensive biomarker for the early identification of patients at high risk for complications. In addition, NLR levels could lead clinicians to perform measures for the optimal therapeutic patient approach.
authors.affiliation: Cardiac Surgery Intensive Care Unit, "Evangelismos" General Hospital of Athens.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Giakoumidakis
authors.affiliation: Faculty of Nursing, School of Healthcare Sciences, National & Kapodistrian University of Athens, Athens.
authors.forename: Nikolaos V
authors.initials: NV
authors.lastname: Fotos
authors.affiliation: Department of Anaesthesiology, University Hospital of Heraklion, Heraklion.
authors.forename: Athina
authors.initials: A
authors.lastname: Patelarou
authors.affiliation: Cardiac Surgery Intensive Care Unit, "Evangelismos" General Hospital of Athens.
authors.forename: Stavros
authors.initials: S
authors.lastname: Theologou
authors.affiliation: Department of Cardiothoracic Surgery, "Evangelismos" General Hospital of Athens.
authors.forename: Mihalis
authors.initials: M
authors.lastname: Argiriou
authors.affiliation: Faculty of Nursing, School of Healthcare Sciences, National & Kapodistrian University of Athens, Athens.
authors.forename: Anastasia A
authors.initials: AA
authors.lastname: Chatziefstratiou
authors.affiliation: Intensive Care Unit, "Korgalenio - Benakio Hellenic Red Cross" General Hospital of Athens, Athens, Greece.
authors.forename: Christina
authors.initials: C
authors.lastname: Katzilieri
authors.affiliation: Faculty of Nursing, School of Healthcare Sciences, National & Kapodistrian University of Athens, Athens.
authors.forename: Hero
authors.initials: H
authors.lastname: Brokalaki
keywords: airway extubation; hospital mortality; intensive care units; length of stay; leukocytes; patient readmission; pneumonia