title: The Relationship Between Preoperative Hemoglobin Concentration, Use of Hospital Resources, and Outcomes in Cardiac Surgery.
abstract: OBJECTIVE
  Preoperative anemia is an established risk factor associated with adverse perioperative outcomes after cardiac surgery. However, limited information exists regarding the relationship between preoperative hemoglobin concentration and outcomes. The aim of this study was to investigate how outcomes are affected by preoperative hemoglobin concentration in a cohort of patients undergoing cardiac surgery.
  
  
  METHODS
  A retrospective, observational cohort study.
  
  
  METHODS
  A single-center tertiary referral hospital.
  
  
  METHODS
  The study comprised 1,972 adult patients undergoing elective and nonelective cardiac surgery.
  
  
  METHODS
  The independent relationship of preoperative hemoglobin concentration was explored on blood transfusion rates, return to the operating room for bleeding and/or cardiac tamponade, postoperative intensive care unit (ICU) and in-hospital length of stay, and mortality.
  
  
  RESULTS
  The overall prevalence of anemia was 32% (629/1,972 patients). For every 1-unit increase in hemoglobin (g/dL), blood transfusion requirements were reduced by 11%, 8%, and 3% for red blood cell units, platelet pools, and fresh frozen plasma units, respectively (adjusted incident rate ratio 0.89 [95% CI 0.87-0.91], 0.92 [0.88-0.97], and 0.97 [0.96-0.99]). For each 1-unit increase in hemoglobin (g/dL), the probability (over time) of discharge from the ICU and hospital increased (adjusted hazard ratio estimates 1.04 [1.00-1.08] and 1.12 [1.12-1.16], respectively).
  
  
  CONCLUSIONS
  A lower preoperative hemoglobin concentration resulted in increased use of hospital resources after cardiac surgery. Each g/dL unit fall in preoperative hemoglobin concentration resulted in increased blood transfusion requirements and increased postoperative ICU and hospital length of stay.
authors.affiliation: Anaesthesia and. Electronic address: George.Hallward@gstt.nhs.uk.
authors.forename: George
authors.initials: G
authors.lastname: Hallward
authors.affiliation: Anaesthesia and.
authors.forename: Nikhail
authors.initials: N
authors.lastname: Balani
authors.affiliation: Anaesthesia and.
authors.forename: Stuart
authors.initials: S
authors.lastname: McCorkell
authors.affiliation: Cardiac Surgery, Guy's and St. Thomas' NHS Foundation Trust, London, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Roxburgh
authors.affiliation: Department of Primary Care and Public Health Sciences, King's College University, London, United Kingdom.
authors.forename: Victoria
authors.initials: V
authors.lastname: Cornelius
mesh_terms: D000368:Aged; D000740:Anemia / Q000097:blood / Q000150:complications* / Q000628:therapy; D001803:Blood Transfusion / Q000706:statistics & numerical data; D006348:Cardiac Surgical Procedures / Q000009:adverse effects*; D005260:Female; D006295:Health Resources / Q000706:statistics & numerical data*; D006454:Hemoglobins / Q000032:analysis*; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D007902:Length of Stay / Q000706:statistics & numerical data; D008131:London; D008297:Male; D008875:Middle Aged; D057234:Preoperative Period; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D006454:Hemoglobins
keywords: anemia; cardiac surgery; hemoglobin; outcomes; preoperative