A historical cohort study of the effect of lowering body iron through blood donation on incident cardiac events

BACKGROUND: Low body iron may protect against atherosclerotic cardiovascular disease through limiting oxidation of low-density lipoprotein cholesterol. Observational studies suggest that donation of whole blood might be associated with reduced risk of cardiovascular events. STUDY DESIGN AND-METHODS: In this retrospective cohort study, a total of 1508 adults who donated more than 1 unit of whole blood each year between 1988 and 1990 (frequent donors) and 1508 age- and sex-matched adults who donated only a single unit in that 3-year period (casual donors) were studied. A standardized questionnaire ascertained participant characteristics and occurrence of incident acute myocardial infarction, coronary angioplasty, coronary bypass surgery, and deaths between 1990 and 2000. Hospital records confirmed events. Cause of death was determined from death certificates. RESULTS: A total of 643 subjects were lost, 113 declined, 156 were deceased but were included in the analysis, and 2104 were surveyed a median of 10 years after the index donation. Frequent donors weighed less and were less likely to be currently taking antihypertensive and lipid-modifying drugs. Events occurred in 6.3 percent of frequent and 10.5 percent of casual donors. After adjustment for group differences, the OR was D.60 (85% CIs 0.43, 0.83; p < 0.001). Events were less frequent in female donors than in male donors and less frequent in subjects who had donated before 1988 than in those who had not donated before 1988. CONCLUSION: Frequent and long-term whole blood donation is associated with a lower risk of cardiovascular events.