Oral iron supplementation is not associated with short-term risk of infections: results from the Danish Blood Donor Study

BACKGROUND Blood donors are at increased risk of developing iron deficiency, and several studies have recommended iron supplementation for this group. The aim of this study was to investigate the effect of oral iron supplementation on risk of infections among healthy blood donors. STUDY DESIGN AND METHODS We included 82,062 participants from the Danish Blood Donor Study who completed a questionnaire on health-related items including use of oral iron supplementation. Infection outcomes were ascertained by using ICD-10 codes in the Danish National Patient Register and Anatomical Therapeutic Chemical codes in the Danish Prescription Register. Multivariable Cox proportional hazards analysis was used as the statistical model. Risk estimates are presented as crude hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS During 19,978 person-years of observation, 6983 donors redeemed at least one prescription of antimicrobials. Similarly, during 19,829 person-years of observation, 242 donors were treated for infection at a hospital. Use of oral iron supplementation was not associated with redeemed prescriptions of antimicrobials in any strata: premenopausal women-HR 1.00, 95% CI 0.91-1.10; postmenopausal women-HR 1.07, 95% CI 0.87-1.32; and men-HR 1.01, 95% CI 0.84-1.21. In addition, use of oral iron supplementation was not associated with risk of hospital-based treatment for infection. CONCLUSION In a large cohort of blood donors, use of oral iron supplementation was not associated with subsequent short-term risk of infection. These findings are important to help understanding the safety of using oral iron supplementation among blood donors and the general population.