title: Blood donation and blood donor mortality after adjustment for a healthy donor effect.
abstract: BACKGROUND
  Studies have repeatedly demonstrated that blood donors experience lower mortality than the general population. While this may suggest a beneficial effect of blood donation, it may also reflect the selection of healthy persons into the donor population. To overcome this bias, we investigated the relation between blood donation frequency and mortality within a large cohort of blood donors. In addition, our analyses also took into consideration the effects of presumed health differences linked to donation behavior.
  
  
  METHODS
  Using the Scandinavian Donation and Transfusion database (SCANDAT), we assessed the association between annual number of donations in 5-year windows and donor mortality by means of Poisson regression analysis. The analyses included adjustment for demographic characteristics and for an internal healthy donor effect, estimated among elderly donors exempted from continued donation because of age criteria.
  
  
  RESULTS
  Statistical analyses included 1,182,495 donors of whom 15,401 died during 9,526,627 person-years of follow-up. Analyses adjusted only for demographic characteristics showed a 18.6% reduction in mortality per additional annual donation (95% confidence interval [CI], 16.8%-20.4%). After additional adjustment for the internal healthy donor effect, each additional annual donation was associated with a 7.5% decreased mortality risk 7.5% (95% CI, 5.7%-9.4%).
  
  
  CONCLUSIONS
  We observed an inverse relationship between donation frequency and mortality. The magnitude of the association was reduced after adjustment for an estimate of self-selection in the donor population. Our observations indicate that repeated blood donation is not associated with premature death, but cannot be interpreted as conclusive evidence of a beneficial health effect.
authors.affiliation: Department of Clinical Immunology, Center of Clinical Investigation, Copenhagen University Hospital.
authors.forename: Henrik
authors.initials: H
authors.lastname: Ullum
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut.
authors.forename: Klaus
authors.initials: K
authors.lastname: Rostgaard
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut.|Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Mads
authors.initials: M
authors.lastname: Kamper-Jørgensen
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Marie
authors.initials: M
authors.lastname: Reilly
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut.
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Olof
authors.initials: O
authors.lastname: Nyrén
authors.affiliation: Department of Immunology and Transfusion Medicine, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: Rut
authors.initials: R
authors.lastname: Norda
authors.affiliation: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden.|Hematology Centre, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Gustaf
authors.initials: G
authors.lastname: Edgren
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut.
authors.forename: Henrik
authors.initials: H
authors.lastname: Hjalgrim
mesh_terms: D001782:Blood Donors; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009026:Mortality; D012189:Retrospective Studies; D012307:Risk Factors