title: Healthy donor effect: its magnitude in health research among blood donors.
abstract: BACKGROUND
  The healthy donor effect has been mentioned as a methodologic problem in blood donor health research. The aim of this study was to investigate different elements of the healthy donor effect.
  
  
  METHODS
  First, recent donors (<4 years registered as a donor) were compared with the general population. Second, active and lapsed donors were compared. Third, short-career donors (<14 donations) were compared with long-career donors (>37 donations). Various health and lifestyle indicators were used as outcome measures.
  
  
  RESULTS
  Compared to the general population, recent donors had a better self-rated health (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.27-1.61), visited the general practitioner (GP) less often (OR, 0.66; 95% CI, 0.60-0.72), and were less often treated by a specialist (OR, 0.83; 95% CI, 0.75-0.93). Recent donors also exhibited a healthier lifestyle compared to the general population. When examining active versus lapsed donors, similar results were found in favor of active donors. With respect to donation career, long-career donors were healthier than short-career donors, but effects were less strong; the ORs were 1.33 (95% CI, 1.15-1.54) for self-rated health, 0.85 (95% CI, 0.76-0.94) for GP visit, and 0.83 (95% CI, 0.68-1.00) for specialist treatment. When comparing long- and short-career donors on lifestyle indicators, there were barely any significant differences.
  
  
  CONCLUSIONS
  The findings strongly point to the presence of a healthy donor effect when comparing donors with the general population and active versus lapsed donors. The healthy donor effect was less pronounced within active donors, when comparing long- and short-career donors. Therefore, health research should primarily be carried out within active donors.
authors.affiliation: Department Donor Studies, Sanquin Research, and the Department of Epidemiology, Biostatistics and HTA, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands.
authors.forename: Femke
authors.initials: F
authors.lastname: Atsma
authors.forename: Ingrid
authors.initials: I
authors.lastname: Veldhuizen
authors.forename: André
authors.initials: A
authors.lastname: Verbeek
authors.forename: Wim
authors.initials: W
authors.lastname: de Kort
authors.forename: Femmie
authors.initials: F
authors.lastname: de Vegt
mesh_terms: D000328:Adult; D000368:Aged; D001782:Blood Donors / Q000523:psychology / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006262:Health; D006305:Health Status Indicators; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D012042:Registries; D012106:Research; D012107:Research Design; D017741:Survivors / Q000706:statistics & numerical data; D055815:Young Adult