title: Blood transfusions: good or bad? Confounding by indication, an underestimated problem in clinical transfusion research.
authors.affiliation: Department of Clinical Epidemiology and the Department of Immunohematology and Blood Bank, Leiden University Medical Center, 2300 RC Leiden, The Netherlands.
authors.forename: Rutger A
authors.initials: RA
authors.lastname: Middelburg
authors.forename: Leo M G
authors.initials: LM
authors.lastname: van de Watering
authors.forename: Johanna G
authors.initials: JG
authors.lastname: van der Bom
mesh_terms: D000818:Animals; D035843:Biomedical Research; D001803:Blood Transfusion; D006801:Humans