title: A review of methods used in comprehensive, descriptive studies that relate red blood cell transfusion to clinical data.
abstract: BACKGROUND
  Red blood cell (RBC) use varies greatly between countries but the underlying reasons are not well understood. Some insight might be gained from blood utilization studies that provide a complete view of the clinical conditions that place individuals at risk of transfusion. This review considers the methodology of published studies that might provide such information and proposes requirements for future studies.
  
  
  METHODS
  A literature search was performed to identify quantitative studies of RBC use related to clinical data, for which the findings are representative of well-defined populations. Extraction and analysis of methodologic information and epidemiologic data were performed.
  
  
  RESULTS
  The 13 studies identified for inclusion varied in their approach to defining the population from which the study sample was selected, classification of clinical data, and method of attributing transfusion events to clinical case groups, including the observational time frame.
  
  
  CONCLUSIONS
  Variability in methods prevents useful interpretation or comparison of the findings. Standardization and transparency of methodology and definitions are essential if future studies are to enable comparison of the factors associated with RBC transfusion in different populations and to improve understanding of the wide variations in RBC use.
authors.affiliation: Scottish National Blood Transfusion Service and the Public Health Sciences, University of Edinburgh, Edinburgh, UK. katherine.biggin@nhs.net
authors.forename: Katherine
authors.initials: K
authors.lastname: Biggin
authors.forename: Pamela
authors.initials: P
authors.lastname: Warner
authors.forename: Robin
authors.initials: R
authors.lastname: Prescott
authors.forename: Brian
authors.initials: B
authors.lastname: McClelland
mesh_terms: D017707:Erythrocyte Transfusion / Q000379:methods*; D004912:Erythrocytes; D006801:Humans