Growing evidence supports healthy older people continuing to donate blood into later life

Internationally, there has long been concern about the suitability of older adults as blood donors. These concerns center on the potential risk of morbidity due to the increasing incidence of cardiovascular disease with age, and an increased risk of adverse reactions, particularly vasovagal reactions, associated with the physiological changes of aging.1 The World Health Organization's blood donor selection guidelines2 indicate a “usual” upper age limit of 65 years but permit physicians to allow first-time donors over 60 and regular donors over 65 to donate (consistent with European recommendations3). Further, on the basis that some countries whose populations have high life expectancies have safely removed upper age limits on donors, the World Health Organization's guidelines suggest that the healthy life expectancy of the population from which donors are drawn can also be considered. Reflecting this potential for discretion, there is wide variation among and within countries in applying age-related eligibility criteria, including the specific upper age limit used and whether additional medical assessment or approval is required.4

In the context of a growing awareness that the over 60s are the fastest-growing age group and will likely comprise up to one-quarter of the populations in most regions of the world by 2050,5 the requirement to restrict blood donation among older people has been challenged. Age restrictions on who can donate blood, coupled with a likely increase in demand from a higher incidence of health conditions in this demographic, has led to concerns about potential blood shortages.6 Several authors have suggested prioritizing strategies to engage young people in blood donation to minimize the risk of shortages resulting from this change in population demographics6, 7; however, reconsideration of the policy of restricting blood donation among older donors has also been put forward as a potential solution, at least for the short to medium term.8

The relative benefits of these two strategies need to be considered, taking into account the cost-effectiveness of recruiting and retaining these donor cohorts, given likely variation in willingness to donate, retention rates, and length of donor career. Consideration of donor age also requires attention to the safety and quality of donated products and any implications for patients in receiving blood from younger versus older donors. However, a particularly critical factor, and the primary focus within the literature to date, is the physical impact of donating blood on donors themselves, in terms of both their immediate safety and their ongoing health.

A 1991 TRANSFUSION editorial noted that limited data were available on the safety of blood donation in later life.9 At that point, much of the evidence was either anecdotal or from studies of autologous older donors, who may not have met standard eligibility criteria, raising concerns about the generalizability of findings to healthy volunteer donors. A study published in that issue indicated that the standard selection process successfully identified contraindicated medical conditions in the older donors recruited (aged 63 years or greater), and those who donated experienced few adverse reactions.10 This supported an earlier study that found no difference in the rate of immediate reactions between donors aged 55–65 years and those 66 years and over.11 A second study in the same TRANSFUSION issue reported a concern about reduced iron stores found in a small sample of older donors.12 However, these researchers did not compare the donors' iron stores with those of younger donors, and it was notable that the sample had donated at a high frequency—five units over 12 months—which is just below the maximum currently allowed for donors of any age by most blood centers in the United States.

In the 27 years since this editorial, evidence on adverse effects of blood donation for older versus younger donors has accumulated, with several large retrospective reviews published. Regression analyses on 2006 data from the American Red Cross examined the impact of sex, age, donor experience, and donor center location on donor complications (defined as vasovagal reactions, and other types of adverse events such as hematomas and painful venipunctures).13 While donors over 60 years of age had a higher proportion of small hematomas than younger donors, Eder and colleagues showed that younger age, rather than older age, was the strongest predictor of adverse reactions to whole blood donation. The complication rate in whole blood donation was low in older donors, with donors aged 80 years or over being three times less likely to suffer a complication from donating than an 18- or 19-year-old and having a risk equivalent to donors in their 40s. Similarly, in apheresis donors, younger age was a risk factor for adverse events, albeit to a smaller degree than with whole blood donation.

Multivariate analyses of Japanese Red Cross Tokyo Blood Center data on vasovagal reactions showed a similar pattern, with younger age (<50 years) found to be the most significant risk factor for an adverse event.14 Donors aged 18 and 19 years were at the highest risk of an adverse event following a 400-mL whole blood donation, while donors aged 50 years to the upper age limit for donating (69 years15) were at a lower risk than all younger age groups.14

Several studies have explored the relationship between donor age and donor reaction severity. Canadian Blood Services data showed that both moderate and severe reactions to whole blood donation decreased with age.1 In contrast, mild reactions decreased with age only until age 49 years, and then increased gradually to age 71 years (the upper age limit at the time of the study). However, the rate of mild reactions in donors aged 60 to 71 years was lower than that of donors under age 20 years. In a German study, donor reactions decreased with age up to 71 years, with a slight increase in the reaction rate of those over 71 years,16 particularly with severe reactions. However, the authors advised interpreting this finding with caution given the small amount of data available for the oldest age groups. Despite this small increase in the oldest age group, the total number of adverse reactions in donors aged 60 years or more was substantially lower than the number observed in donors less than 30 years old and somewhat lower than those observed in donors in their 30s.

In examining the most severe forms of vasovagal reactions, Bravo and colleagues17 focused on risk factors for loss of consciousness in donors. In this US study, young age (under 25 years) was associated with a higher risk of loss of consciousness, with 17- and 18-year-old donors at particularly high risk. While donors over 65 years were at a lower risk of fainting before or during the donation, they were at a slightly higher risk of fainting immediately after donation compared to donors aged 25–65 years; however, this risk for older donors was still considerably lower than for donors aged 17 to 24 years.

To date, examinations of the safety of blood donation for older donors have analyzed data from only a single country or blood center, with considerable variation in the upper age of the samples and age categories used. While the existing research consistently finds young donors at particularly high risk of an adverse reaction to blood donation, it has remained unclear whether the oldest donors may be at increased risk of certain adverse outcomes compared to donors in their middle years or those approaching older age. The study by Goldman and colleagues18 on behalf of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative in this issue of TRANSFUSION provides valuable additional insights. The authors analyzed data from more than 200,000 donors over 70 years of age who presented at 12 blood centers across five countries (Canada, Australia, England/North Wales, New Zealand, and the United States), all of which, except Australia, had eliminated upper age limits. Reaction rates in each country were examined using consistent age categories (24–70 years, and 71 years and older); unlike previous studies, young donors, who are already known to be at highest risk of adverse outcomes, were not included in these analyses. The results indicated that total rates of vasovagal reactions were lower among donors over 70 years than in donors aged 24 to 70 years, for both males and females. Vasovagal reactions with loss of consciousness were less common among older males, but rates in younger and older women were equivalent. This study provides compelling evidence of the safety of blood donation for the oldest adults, particularly given that there was no cap on donor age in most countries providing data.

The medium- to longer-term health effects of blood donation also require consideration. Earlier literature found no evidence that blood donation impacts the physical fitness of older donors, with older donors showing similar compensatory mechanisms as younger donors and tolerating blood loss well.19, 20 Studies have also explored the relative risk of depletion of iron stores among different age groups, which is a critical health issue for blood donors. Retrospective reviews show that younger donors are the key age group at risk, with young women at particularly high risk of iron deficiency.21, 22 Badami and Taylor reported that New Zealanders over 50 years old had higher serum ferritin levels than younger age groups and were less likely to experience borderline or low iron status.23 In Denmark, a similar positive association between increasing age and higher iron stores among donors was observed among men as well as premenopausal and postmenopausal women.24 Thus, mirroring the findings for donor adverse events, there is a consistent body of literature indicating a high risk of low iron stores among younger rather than older donors.

While it appears that older donors can donate without undue health or safety risks to themselves, it is important to consider the quality and safety of the products donated by these donors and any implications for the recipients. Researchers have reported that exposure to RBCs from donors aged 45 years or younger are associated with increased patient mortality compared to blood from older donors25; although others have interpreted the available evidence as indicating that the age of donors of RBC units is unlikely to impact the survival of patients receiving a transfusion.26 Research into the impact of donor age on RBC storage is under way, with suggestions that a predisposition to oxidative hemolysis is modulated by donor age.27 However, it is not known whether this has implications for patient outcomes. A study of the quality of fresh frozen plasma also concluded that there were no concerns about older donors contributing to the production of therapeutic or fractionated plasma.28 Meanwhile, Bontekoe and colleagues29 conducted a study of platelet quality in a small sample of donors and concluded that while there was poorer in vitro quality in platelets from older donors, this was unlikely to impact blood bank practice, and clinical implications are not known.

When considering the requirement for age-based eligibility criteria to effectively protect the health of donors, available evidence would indicate that 1) the minimum donation age should be reexamined to reduce potential harms from vasovagal reactions and iron deficiency among high-risk youth donors, and 2) the upper age limit is unnecessary, given that medical conditions that place donors at risk are already detected by standard blood center health screening.30 Studies examining the impact of raising or removing the upper age limit suggest that this does not increase the risks for donors who meet other eligibility criteria and is welcomed by donors.16, 31 To illustrate, Goldman and colleagues31 described the response to a new initiative at the Canadian Blood Services allowing regular donors to continue to donate beyond their 71st birthday, provided they had an annual medical assessment from their own physician. Even when presented with this additional requirement, a high proportion of invited donors agreed to donate, and nearly all donated successfully. The impact of removing the upper age limit in Germany for repeat donors, based on prior trial data, has also been positively reported, with a constant increase in blood donations made by older donors following the change.16

Changing the upper age criteria may offer multiple benefits for blood centers. Fan and colleagues32 conducted population modeling to estimate the Canadian population that would be eligible to donate with different upper age limits. Here, removal of the upper age limit would lead to a 5% increase in the population potentially eligible to donate, despite the higher disease prevalence among older adults. Also, enabling existing donors to continue to donate into later life reduces the need to replace aging donors with new recruits. Existing donors are a safer, more cost-effective source of blood than new recruits, and existing donors have a lower rate of adverse events.13, 14, 17

When allowed to donate, older donors “punch above their weight,” making a more substantial contribution to the blood supply than younger donors. The BEST Collaborative study reported that while donors aged 70+ years accounted for only 1.0% to 4.2% of the donor population in each country, they contributed 1.5% to 5.7% of total donations.18 This is consistent with earlier research showing that older donors make more donations per year than younger donors.8, 16, 30 The reasons for this are likely multifaceted. Healthy older donors may be less likely than young donors to experience “lifestyle” interruptions to their donor careers (e.g., through changing jobs, moving, pregnancy/breastfeeding, and getting a tattoo). Further, older donors may have fewer critical time and inconvenience barriers to donating,33, 34 having either reduced their working hours or stopped work completely. Finally, older donors may have made more prior donations than younger adults,35 resulting in higher levels of commitment and reliability.36

Alternatively, the higher contribution made by older donors may reflect motivational differences between the age groups. Charbonneau and colleagues37 found that donors aged 50 to 55 years were more strongly motivated to donate by reasons relating to others, such as wanting to save lives, believing that there is a strong need for blood products and because they knew someone who had received blood in the past, compared with younger donors. However, there has been little research into the meaning of blood donation for older adults. One hypothesis derived from Terror Management Theory is that older donors' awareness of their own mortality and that of others close to them is particularly motivating.38 Alternatively, it may be that, for older adults, donating blood is a component of healthy aging, whereby being healthy enough to donate blood indicates they are “aging well.” Thus, the opportunity to successfully donate blood and reinforce their identities as healthy, productive donors may motivate continued donation. This idea is supported by observations from Zeiler and colleagues,16 who suggested that older donors in Germany tended to view being eligible to donate as proof of their good health and performance. However, this tendency may also have implications for how blood centers manage older donors, given suggestions that some older donors may have felt “personally insulted” when they were deferred from donating after failing to meet standard eligibility criteria.16

In conclusion, the safety of donating blood in later life has now received considerable attention, with results supporting older adults continuing to donate. A greater number of older people living healthier lives for longer39 means that this demographic potentially represents a significant resource that has generally not been the focus of donor recruitment and retention campaigns. However, with this recognition comes an awareness of the many gaps in our knowledge. Specifically, we lack information about the motivations and experiences of older donors, particularly from the donors themselves, to guide blood center efforts with this group. For example, we know little about how older adults make decisions about starting or continuing to donate blood and how this might relate to key life events such as retirement. Without an upper age limit, issues around the cognitive capacity of older donors to give informed consent to donate and to provide reliable information during health assessments may also require consideration.

Whether the current move to online and digital platforms and embracing of emerging technologies40 provides an optimal experience for older donors has received little attention. Further, the potential of blood donation centers to provide something extra to our older donors in terms of social connectedness to enhance well-being41 at a life stage where they may become particularly vulnerable to social disconnection and loneliness42 is unexplored. Finally, given the potential importance of donating to older donors' identity as “healthy agers,”16 how to transition older donors out of donating due to health concerns—either temporarily or permanently—potentially requires great care and attention if older donors are to become a more substantial group within our donor cohort.

CONFLICTS OF INTEREST

The authors have disclosed no conflicts of interest.