title: The intention-to-treat principle in clinical trials and meta-analyses of leukoreduced blood transfusions in surgical patients.
abstract: BACKGROUND
  The scientific method requires that only experiments actually and correctly performed be used to draw conclusions. The intention-to-treat principle requires that all patients, even those not or improperly treated, be included. In clinical trials and meta-analyses investigating leukoreduced blood transfusions to reduce postoperative infections, the intention-to-treat principle and the scientific method have been variably applied.
  
  
  METHODS
  Clinical trials and meta-analyses were retrieved from the literature, and their scientific and statistical methods were assessed. A meta-analysis emphasizing the scientific method was created, restricted to patients who actually received transfusions, given that patients who did not receive transfusions cannot benefit from leukoreduction.
  
  
  RESULTS
  Nine clinical trials and 11 meta-analyses were identified. In 2 of the trials and all but 1 of the meta-analyses, conclusions were based on data that included many (>10%) patients who had been randomly assigned but not received a transfusion or data not derived from investigative results. Limiting the meta-analysis to patients who actually received transfusions (n = 3093), demonstrated that leukoreduced transfusions significantly reduced the odds of postoperative infection (summary odds ratio, 0.522; 95% confidence interval, 0.332-0.821; p = 0.005).
  
  
  CONCLUSIONS
  When data restricted to patients receiving transfusions are analyzed, and no data absent from the actual investigations are introduced, leukoreduced transfusions substantially and significantly reduce the odds of postoperative infection by approximately 50 percent. These results demonstrate the importance of including only scientifically valid data in clinical trials and meta-analyses. The intention-to-treat principle should never lead to inclusion of data not actually derived from experimental results.
authors: University of Rochester Medical Center, Rochester, New York 14642, USA. Neil_Blumberg@urmc.rochester.edu
authors: Neil
authors: N
authors: Blumberg
authors: Hongwei
authors: H
authors: Zhao
authors: Hongkun
authors: H
authors: Wang
authors: Susan
authors: S
authors: Messing
authors: Joanna M
authors: JM
authors: Heal
authors: Gary H
authors: GH
authors: Lyman
mesh_terms: D001788:Blood Grouping and Crossmatching / Q000706:statistics & numerical data; D001803:Blood Transfusion / Q000706:statistics & numerical data*; D006801:Humans; D047589:Leukocyte Reduction Procedures; D016017:Odds Ratio; D011183:Postoperative Complications / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic / Q000379:methods / Q000706:statistics & numerical data*