title: Anemia and blood transfusion in critically ill patients.
abstract: BACKGROUND
  Anemia is a common problem in critically ill patients admitted to intensive care units (ICUs), but the consequences of anemia on morbidity and mortality in the critically ill is poorly defined.
  
  
  OBJECTIVE
  To prospectively define the incidence of anemia and use of red blood cell (RBC) transfusions in critically ill patients and to explore the potential benefits and risks associated with transfusion in the ICU.
  
  
  METHODS
  Prospective observational study conducted November 1999, with 2 components: a blood sampling study and an anemia and blood transfusion study.
  
  
  METHODS
  The blood sampling study included 1136 patients from 145 western European ICUs, and the anemia and blood transfusion study included 3534 patients from 146 western European ICUs. Patients were followed up for 28 days or until hospital discharge, interinstitutional transfer, or death.
  
  
  METHODS
  Frequency of blood drawing and associated volume of blood drawn, collected over a 24-hour period; hemoglobin levels, transfusion rate, organ dysfunction (assessed using the Sequential Organ Failure Assessment score), and mortality, collected throughout a 2-week period.
  
  
  RESULTS
  The mean (SD) volume per blood draw was 10.3 (6.6) mL, with an average total volume of 41.1 (39.7) mL during the 24-hour period. There was a positive correlation between organ dysfunction and the number of blood draws (r = 0.34; P<.001) and total volume drawn (r = 0.28; P<.001). The mean hemoglobin concentration at ICU admission was 11.3 (2.3) g/dL, with 29% (963/3295) having a concentration of less than 10 g/dL. The transfusion rate during the ICU period was 37.0% (1307/3534). Older patients and those with a longer ICU length of stay were more commonly transfused. Both ICU and overall mortality rates were significantly higher in patients who had vs had not received a transfusion (ICU rates: 18.5% vs 10.1%, respectively; chi(2) = 50.1; P<.001; overall rates: 29.0% vs 14.9%, respectively; chi(2) = 88.1; P<.001). For similar degrees of organ dysfunction, patients who had a transfusion had a higher mortality rate. For matched patients in the propensity analysis, the 28-day mortality was 22.7% among patients with transfusions and 17.1% among those without (P =.02); the Kaplan-Meier log-rank test confirmed this difference.
  
  
  CONCLUSIONS
  This multicenter observational study reveals the common occurrence of anemia and the large use of blood transfusion in critically ill patients. Additionally, this epidemiologic study provides evidence of an association between transfusions and diminished organ function as well as between transfusions and mortality.
authors.affiliation: Department of Intensive Care, Erasme University Hospital, Route de Lennik 808, Brussels, 1070, Belgium. jlvincen@ulb.ac.be
authors.forename: Jean Louis
authors.initials: JL
authors.lastname: Vincent
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Baron
authors.forename: Konrad
authors.initials: K
authors.lastname: Reinhart
authors.forename: Luciano
authors.initials: L
authors.lastname: Gattinoni
authors.forename: Lambert
authors.initials: L
authors.lastname: Thijs
authors.forename: Andrew
authors.initials: A
authors.lastname: Webb
authors.forename: Andreas
authors.initials: A
authors.lastname: Meier-Hellmann
authors.forename: Guy
authors.initials: G
authors.lastname: Nollet
authors.forename: Daliana
authors.initials: D
authors.lastname: Peres-Bota
mesh_terms: D018806:APACHE; D000328:Adult; D000368:Aged; D000740:Anemia / Q000453:epidemiology / Q000628:therapy*; D016638:Critical Illness / Q000401:mortality*; D017707:Erythrocyte Transfusion / Q000706:statistics & numerical data; D005060:Europe / Q000453:epidemiology; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009102:Multiple Organ Failure; D015999:Multivariate Analysis; D012306:Risk; D012720:Severity of Illness Index; D016019:Survival Analysis
chemical_list: D006454:Hemoglobins