Objectives

The Retrovirus Epidemiology Donor Study-II (REDS-II) Donor Iron Status Evaluation Study (RISE) was designed to evaluate the effects of blood donation intensity on iron and hemoglobin (Hb) status, assess factors that could modify that relationship, and provide data to help formulate optimal whole blood donation frequency.

Background

Previous studies have shown that regular blood donors are at risk of iron deficiency. Also, a polymorphism in transferrin, which increases the likelihood that menstruating women will be iron deficient, and several genes for hemochromatosis were described in other previous studies. Findings from these studies lead to the possibility that genetic markers might define “at-risk” and “protected” donor groups with respect to iron depletion in blood donors. In addition, none of the previous donor studies had assessed the influence of racial/ethnic or socioeconomic factors, nor behavioral variables and dietary intake. Also, the availability of new tests of body iron status provided further opportunities to detect or prevent this problem. For these reasons, the National Heart, Lung, and Blood Institute’s (NHLBI) Retrovirus Epidemiology Donor Study – II (REDS-II) program conducted the REDS-II Donor Iron Status Evaluation (RISE) whereby blood donors were followed prospectively for 15-24 months to provide an in-depth and contemporary evaluation of iron status in a US blood donor population.

Participants

The RISE study was a longitudinal multi-center study conducted between 2007 and 2009. All six REDS-II blood centers participated in the study: American Red Cross New England Region, Dedham, MA; the American Red Cross Southern Region, Atlanta, Georgia; the Blood Center of Wisconsin, Milwaukee, Wisconsin; the Hoxworth Blood Center/University of Cincinnati Medical Center, Cincinnati, Ohio; the Institute for Transfusion Medicine, Pittsburgh, Pennsylvania; and the Blood Centers of the Pacific, San Francisco, California. Two cohorts (2,425 whole blood or double red blood cell donors total) were established; one consisted of 888 first-time (FT) or reactivated (RA) donors and the other consisted of 1,537 frequent donors. The FT/ RA cohort consisted of men and women who had either never given blood before (FT) or had not given a donation in the two years before enrollment (RA). The frequent donor cohort consisted of men who had given the equivalent of ≥ 3 and women who had given ≥ 2 red blood cell units in the last year (or equivalent double-red blood cell donations). Male and females donors were recruited equally for each cohort. Most sites where donors were recruited were fixed rather than mobile sites. Only individuals who successfully donated whole blood or double-RBC units, were not deferred at their enrollment visit, and had agreed to donate frequently in the following 24 months were included in the study.

Design

Data on previous blood donation history; smoking history; diet; use of vitamins, supplements, and aspirin; and reproductive history (female donors) were collected through a self-administered enrollment questionnaire. Also, blood donation activity before and after enrollment, height, weight, country of birth, race and/or ethnicity, and highest educational level were compiled from blood center records and the donor information form that donors completed at the time of donation at the REDS-II centers. At enrollment, ferritin, soluble transferrin receptor (sTfR), and fingerstick and venous hemoglobin were determined. Models to predict two measures of iron deficiency, absent iron stores (AIS) and iron-deficient erythropoiesis (IDE), and hemoglobin deferral were developed. Absent iron stores (AIS) were indicated by a ferritin level of less than 12 ng/mL and iron-deficient erythropoiesis (IDE) by a log(sTfR/ferritin) value of 2.07 or greater, corresponding to the 97.5 percentile of the distribution of the log (sTfR/ferritin) in FT/RA males at enrollment. For hemoglobin deferral, a donor was deferred by current standards if their hemoglobin was < 12.5 g/dL or hematocrit < 38% using routine fingerstick methods, which differed among the six centers.

Conclusions

A large proportion of both female and male frequent blood donors have iron depletion. Strong associations between higher prior donation intensity and a shorter time since last donation and iron depletion were observed. Iron depletion also developed in a high proportion of returning FT/RA donors (51% of females and 20% of male had IDE on follow up). Other than donation intensity and time since last donation, gender, weight, age, and the use of self-administered iron supplements were found to be important independent predictors of AIS and/or IDE. Time since last red cell donation was a highly significant factor for hemoglobin deferral as were black race, female gender and younger age in women. Reducing the frequency of blood donation is likely to reduce the prevalence of iron deficiency among blood donors, as might implementing routine iron supplementation.

Publications

Brittenham, G. M. (2011), Iron deficiency in whole blood donors. Transfusion, 51: 458–461.

Cable, R. G., Glynn, S. A., Kiss, J. E., Mast, A. E., Steele, W. R., Murphy, E. L., Wright, D. J., Sacher, R. A., Gottschall, J. L., Vij, V., Simon, T. L. and for the NHLBI Retrovirus Epidemiology Donor Study-II (REDS-II) (2011), Iron deficiency in blood donors: analysis of enrollment data from the REDS-II Donor Iron Status Evaluation (RISE) study. Transfusion, 51: 511–522.

Cable, R. G., Glynn, S. A., Kiss, J. E., Mast, A. E., Steele, W. R., Murphy, E. L., Wright, D. J., Sacher, R. A., Gottschall, J. L., Tobler L.H., Simon, T. L. and for the NHLBI Retrovirus Epidemiology Donor Study-II (REDS-II) (2011), Iron deficiency in blood donors: the REDS-II Donor Iron Status Evaluation (RISE) study. Transfusion, In Press.

Cable RG, Steele WR, Melmed RS, Johnson B, Mast AE, Carey PM, Kiss JE, Kleinman SH, Wright DJ for the NHLBI Retrovirus Epidemiology Donor Study-II (REDS-II). The Difference Between Fingerstick And Venous Hemoglobin/Hematocrit Varies by Gender and Iron Stores. Transfusion, In Press.

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