POSSIBLE ASSOCIATION OF A REDUCTION IN CARDIOVASCULAR EVENTS WITH BLOOD DONATION

Background-The iron hypothesis suggests that females are protected fro m atherosclerosis by having lower iron stores than men, thus limiting oxidation of lipids. Objective-To test the iron hypothesis by comparin g cardiovascular event rates in whole blood donors compared with non-d onors. Design-Prospective cohort with telephone survey follow up. Sett ing-The State of Nebraska, USA. Participants-A sample was selected fro m the Nebraska Diet Heart Survey (NDHS) restricting for age greater th an or equal to 40 years and absence of clinically apparent vascular di seases at time of enrollment in to NDHS (1985-87). Main outcome measur es-The occurrence of cardiovascular events (myocardial infarction, ang ina, stroke), procedures (angioplasty, bypass surgery, claudication, e ndarterectomy), nitroglycerin use, or death (all cause mortality), and level of blood donation. Results-Participants were 655 blood donors a nd 3200 non-donors who differed in education, physical activity, diabe tes, and frequency of antihypertensive treatment; 889 were lost to fol low up. Sixty four donors and 567 non-donors reported cardiovascular e vents (crude odds ratio = 0.50, 95% confidence interval (CI) 0.38-0.66 ). The benefit of donation was confined to non-smoking males (adjusted odds ratio 0.67, 95% CI 0.45-0.99). Benefit was limited to current do nors (the most recent three years). No additional benefit resulted fro m donating more than once or twice over three years. Conclusion-In sup port of the iron hypothesis, blood donation in non-smoking men in this cohort was associated with reduced risk of cardiovascular events. A r andomised clinical trial is warranted to confirm these findings as the observed personal health benefit of donation has public policy ramifi cations.