title: Red blood cell transfusion is a determinant of neurological complications after cardiac surgery.
abstract: OBJECTIVE
  The aim of this study was to evaluate the impact of red blood cell (RBC) transfusions on the occurrence of stroke and transient ischaemic attack (TIA) after cardiac surgery.
  
  
  METHODS
  Data on 14 956 patients undergoing coronary artery bypass grafting (CABG) and valve surgery (with or without concomitant CABG) were retrieved at three European University Hospitals. The prognostic impact of RBC transfusion on postoperative stroke and TIA was investigated by logistic regression and multilevel propensity score analysis.
  
  
  RESULTS
  Postoperative stroke was observed in 147 (1.0%) patients and combined stroke/TIA in 238 (1.6%). Of the total population, 6439 (43%) patients received RBC transfusion with a median of 2 units (25th-75th percentile, 2-4 units). When adjusted for other significant risk factors, RBC transfusion was an independent predictor of stroke [odds ratio (OR) 1.14; 95% confidence interval (CI) 1.11-1.17 per unit] and stroke/TIA (OR 1.12; 95% CI 1.09-1.15 per unit). Increase in the amount of transfused RBC units was associated with higher rates of stroke (no RBC transfusion: 0.5%, 1-2 RBC units: 1.0%, OR 1.42; >2 RBC units: 2.7%, OR 3.10) and stroke/TIA (no RBC transfusion: 0.8%, 1-2 RBC units: 1.8%, OR 1.49; >2 RBC units: 4.0%, OR 2.72). Multilevel propensity score analysis confirmed these findings and showed a very high risk of stroke (3.9%; OR 3.85; 95% CI 2.30-6.45) and stroke/TIA (5.9%; OR 3.30; 95% CI 2.17-5.02) associated with transfusion of ≥6 units of RBCs.
  
  
  CONCLUSIONS
  Transfusion of more than 2 units of RBCs after cardiac surgery is associated with a significantly increased risk of postoperative stroke and TIA.
authors.affiliation: Department of Heart and Vessels, Cardiac Surgery Unit, Varese University Hospital, Varese, Italy giovannimariscalco@yahoo.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Mariscalco
authors.affiliation: Division of Cardiac Surgery and Department of Surgery, University of Oulu, Oulu, Finland.
authors.forename: Fausto
authors.initials: F
authors.lastname: Biancari
authors.affiliation: Division of Cardiac Surgery and Department of Surgery, University of Oulu, Oulu, Finland.
authors.forename: Tatu
authors.initials: T
authors.lastname: Juvonen
authors.affiliation: Department of Cardiovascular Sciences, Cardiac Surgery, Centro Cardiologico Monzino IRCCS, University of Milan, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Zanobini
authors.affiliation: Department of Surgical and Morphological Sciences, Cardiac Surgery Unit, Varese University Hospital, University of Insubria, Varese, Italy.
authors.forename: Marzia
authors.initials: M
authors.lastname: Cottini
authors.affiliation: Department of Hypertension, Chair of Nephrology and Hypertension, Medical University of Lodz, Lodz, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Banach
authors.affiliation: Department of Cardiovascular Sciences, Clinical Sciences Wing, Glenfield General Hospital, University of Leicester, Leicester, UK.
authors.forename: Gavin J
authors.initials: GJ
authors.lastname: Murphy
authors.affiliation: Department of Surgical and Morphological Sciences, Cardiac Surgery Unit, Varese University Hospital, University of Insubria, Varese, Italy.
authors.forename: Cesare
authors.initials: C
authors.lastname: Beghi
authors.affiliation: Bristol Heart Institute, University of Bristol and Imperial College of London, London, UK.
authors.forename: Gianni D
authors.initials: GD
authors.lastname: Angelini
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000401:mortality; D017707:Erythrocyte Transfusion / Q000009:adverse effects* / Q000401:mortality; D005060:Europe; D005260:Female; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects* / Q000401:mortality; D017052:Hospital Mortality; D006785:Hospitals, University; D006801:Humans; D002546:Ischemic Attack, Transient / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D057216:Propensity Score; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D013997:Time Factors; D016896:Treatment Outcome
keywords: Aortic valve; Blood transfusion; Cardiac surgery; Coronary artery bypass; Mitral valve; Stroke; Transient ischaemic attack