title: Impact of more restrictive blood transfusion strategies on clinical outcomes: a meta-analysis and systematic review.
abstract: BACKGROUND
  There is accumulating evidence that restricting blood transfusions improves outcomes, with newer trials showing greater benefit from more restrictive strategies. We systematically evaluated the impact of various transfusion triggers on clinical outcomes.
  
  
  METHODS
  The MEDLINE database was searched from 1966 to April 2013 to find randomized trials evaluating a restrictive hemoglobin transfusion trigger of <7 g/dL, compared with a more liberal trigger. Two investigators independently extracted data from the trials. Outcomes evaluated included mortality, acute coronary syndrome, pulmonary edema, infections, rebleeding, number of patients transfused, and units of blood transfused per patient. Extracted data also included information on study setting, design, participant characteristics, and risk for bias of the included trials. A secondary analysis evaluated trials using less restrictive transfusion triggers, and a systematic review of observational studies evaluated more restrictive triggers.
  
  
  RESULTS
  In the primary analysis, pooled results from 3 trials with 2364 participants showed that a restrictive hemoglobin transfusion trigger of <7 g/dL resulted in reduced in-hospital mortality (risk ratio [RR], 0.74; confidence interval [CI], 0.60-0.92), total mortality (RR, 0.80; CI, 0.65-0.98), rebleeding (RR, 0.64; CI, 0.45-0.90), acute coronary syndrome (RR, 0.44; CI, 0.22-0.89), pulmonary edema (RR, 0.48; CI, 0.33-0.72), and bacterial infections (RR, 0.86; CI, 0.73-1.00), compared with a more liberal strategy. The number needed to treat with a restrictive strategy to prevent 1 death was 33. Pooled data from randomized trials with less restrictive transfusion strategies showed no significant effect on outcomes.
  
  
  CONCLUSIONS
  In patients with critical illness or bleed, restricting blood transfusions by using a hemoglobin trigger of <7 g/dL significantly reduces cardiac events, rebleeding, bacterial infections, and total mortality. A less restrictive transfusion strategy was not effective.
authors: Stanford University School of Medicine, Stanford, Calif. Electronic address: salpeter@stanford.edu.
authors: Shelley R
authors: SR
authors: Salpeter
authors: Brown University, Providence, RI.
authors: Jacob S
authors: JS
authors: Buckley
authors: St Luke's - Roosevelt Hospital Center, New York, NY.
authors: Saurav
authors: S
authors: Chatterjee
mesh_terms: D054058:Acute Coronary Syndrome / Q000453:epidemiology / Q000517:prevention & control; D001424:Bacterial Infections / Q000209:etiology / Q000517:prevention & control; D001803:Blood Transfusion / Q000401:mortality / Q000592:standards* / Q000706:statistics & numerical data*; D015986:Confounding Factors, Epidemiologic; D016638:Critical Illness; D019317:Evidence-Based Medicine; D006454:Hemoglobins / Q000032:analysis* / Q000378:metabolism; D006470:Hemorrhage / Q000453:epidemiology / Q000517:prevention & control; D017052:Hospital Mortality; D006801:Humans; D016017:Odds Ratio; D011654:Pulmonary Edema / Q000453:epidemiology / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic
chemical_list: D006454:Hemoglobins
keywords: Clinical outcomes; Meta-analysis; Mortality; Systematic review; Transfusion