title: Iron and cardiac ischemia: a natural, quasi-random experiment comparing eligible with disqualified blood donors.
abstract: BACKGROUND
  The theory that elevated iron stores can induce vascular injury and ischemia remains controversial. We conducted a cohort study of the effect of blood donation on the risk of coronary heart disease (CHD) by taking advantage of the quasi-random exclusion of donors who obtained a falsely reactive test for a transmissible disease (TD) marker.
  
  
  METHODS
  Whole blood donors who were permanently disqualified because of a false-reactive test between 1990 and 2007 in the province of Quebec were compared to donors who remained eligible, matched for baseline characteristics. The incidence of CHD after entry into the study was determined through hospitalization and death records. We compared eligible and disqualified donors using an "intention-to-treat" framework.
  
  
  RESULTS
  Overall, 12,357 donors who were permanently disqualified were followed for 124,123 person-years of observation, plus 50,889 donors who remained eligible (516,823 person-years). On average, donors who remained eligible made 0.36 donation/year during follow-up and had an incidence of hospitalizations or deaths attributable to CHD of 3.60/1000 person-years, compared to 3.52 among permanently disqualified donors (rate ratio, 1.02; 95% confidence interval, 0.92-1.13).
  
  
  CONCLUSIONS
  Donors who remained eligible did not have a lower risk of CHD, compared to donors who were permanently disqualified due to a false-reactive TD marker. Because of the quasi-random nature of false-reactive screening tests, this natural experiment has a level of validity approaching that of a randomized trial evaluating the effect of regular blood donation on CHD risk. These results do not support the iron hypothesis.
authors: Héma-Québec, Sainte-Foy, Quebec, Canada. marc.germain@hema-quebec.qc.ca
authors: Marc
authors: M
authors: Germain
authors: Gilles
authors: G
authors: Delage
authors: Claudia
authors: C
authors: Blais
authors: Elizabeth
authors: E
authors: Maunsell
authors: Francine
authors: F
authors: Décary
authors: Yves
authors: Y
authors: Grégoire
mesh_terms: D000293:Adolescent; D000328:Adult; D001782:Blood Donors / Q000706:statistics & numerical data*; D003327:Coronary Disease / Q000453:epidemiology* / Q000401:mortality; D005188:False Negative Reactions; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007501:Iron / Q000097:blood; D019190:Iron Overload / Q000097:blood / Q000453:epidemiology* / Q000401:mortality; D007511:Ischemia / Q000453:epidemiology* / Q000401:mortality; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011725:Pyridines; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors; D055815:Young Adult
chemical_list: D011725:Pyridines; C108850:V 10367; D007501:Iron