title: Effect of peri-operative red blood cell transfusion on 30-day and 1-year mortality following coronary artery bypass surgery.
abstract: OBJECTIVE
  The purpose of this study was to examine the effect of peri-operative red blood cell (RBC) transfusion on 30-day and 1-year mortality following coronary artery bypass grafting (CABG).
  
  
  METHODS
  We retrospectively analysed 3024 consecutive patients who underwent isolated CABG between January 1999 and December 2001. Patient records were linked to the National Strategic Tracing Service, which records all mortality in the UK. Thirty-day and 1-year mortality were derived from Kaplan-Meier curves. Confounding variables were controlled for by constructing a propensity score for the probability of receiving a transfusion from core patient characteristics including the lowest recorded laboratory haemoglobin (LL Hb) from a clinical chemistry database (C statistic 0.81). The propensity score and the comparison variable (transfusion versus no transfusion) were included in a Cox proportional hazards analysis, allowing calculation of adjusted hazard ratios (HR) and Kaplan-Meier survival curves.
  
  
  RESULTS
  Nine hundred and forty (31.1%) patients received RBC transfusion during or within 72h of surgery. Predictors of the need for transfusion were LL Hb and lower body mass index, use of cardiopulmonary bypass, female sex, number of grafts, renal dysfunction, increased age, extent of disease, and prior CABG; these factors were all included in the propensity score. After 1-year of follow-up, 122 (4.03%) deaths occurred. The crude HR for 1-year mortality in patients transfused was 3.0 (P<0.001). After adjusting for the propensity score, re-operation for bleeding, peri-operative blood loss and post-operative complications, the adjusted 30-day mortality was 1.9% in transfused patients compared to 1.1% in patients not transfused (P<0.05). The adjusted HR for 1-year mortality in patients transfused was 1.88 (P<0.01).
  
  
  CONCLUSIONS
  Peri-operative RBC transfusion after CABG is associated with an increased risk of mortality during a 1-year follow-up period, with a large proportion of deaths occurring within 30-days.
authors.affiliation: Department of Cardiothoracic Surgery, The Cardiothoracic Centre-Liverpool, Thomas Drive, Liverpool L14 3PE, UK. manojkud@hotmail.com
authors.forename: Manoj
authors.initials: M
authors.lastname: Kuduvalli
authors.forename: Aung Y
authors.initials: AY
authors.lastname: Oo
authors.forename: Nick
authors.initials: N
authors.lastname: Newall
authors.forename: Antony D
authors.initials: AD
authors.lastname: Grayson
authors.forename: Mark
authors.initials: M
authors.lastname: Jackson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Desmond
authors.forename: Brian M
authors.initials: BM
authors.lastname: Fabri
authors.forename: Abbas
authors.initials: A
authors.lastname: Rashid
mesh_terms: D000368:Aged; D001026:Coronary Artery Bypass / Q000401:mortality*; D004739:England / Q000453:epidemiology; D004812:Epidemiologic Methods; D017707:Erythrocyte Transfusion / Q000009:adverse effects* / Q000401:mortality; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019990:Perioperative Care / Q000009:adverse effects; D011183:Postoperative Complications; D011184:Postoperative Period