Only individuals in good health should be accepted as blood donors. Good health is difficult to define, but certain associated parameters may be established from a brief medical history, observation and simple tests. Staff undertaking donor health and risk assessment should be well-trained in the observation of donor appearance and detection of signs of ill health. Staff should receive explicit guidance on what to look for and when to refer a donor to a health-care professional for further medical attention.
Donors should feel well on the day of donation and be able to perform their routine daily activities. Information about minor illnesses, exposure to communicable diseases, travel to disease endemic areas, pregnancy and lactation and medical and surgical interventions should be elicited so as to determine suitability for blood donation or the need for deferral. The BTS physician may request additional information and advice about the health of a prospective donor from the donor's own doctor or specialist.
Sections 4, 5, 6 and 7 contain recommendations on acceptance and deferral of donors based on selection criteria which fall into four broad categories:
Conditions that are acceptable
Conditions that require temporary deferral for defined periods of time
Conditions that require permanent deferral
Conditions that require individual assessment.
4.1. AGE
4.1.1. Lower age limit
A lower age limit should be set for blood donation, taking into account national legal requirements for consent, the increased risk of vasovagal reactions in younger donors, and the increased iron requirements of adolescents and young menstruating females.
The lower age limit for blood donation in most countries is 18 years, although in some countries national legislation permits 16–17 year-olds to donate provided that they fulfil the physical and haematological criteria required and that appropriate consent is obtained.
Studies of adverse events in blood donors have shown an increased rate of vasovagal reactions in younger donors (50,52); a study conducted in the United States of America in 2006 reported a 10.7% risk of a vasovagal reaction in donors aged 16–17 years, compared with 8.3% in 18–19 year-olds and 2.8% in donors aged 20 years or older (53). The age of 16 should therefore be an absolute lower limit for blood donation to ensure donor health and safety.
Adolescents of either gender are at risk of iron deficiency during the pubertal growth spurt when the average daily total requirement of absorbed elemental iron is 1.50 mg/day for males aged 15–17 years and 1.62 mg/day for females (54,55).
Recommendations
The usual lower age limit for blood donation is 18 years
Where permitted by national legislation or in setting a lower age limit of 16 or 17 years for blood donation, the BTS should consider:
- —
The age of legal consent below which parental permission is required and the need to inform parents/guardians about the process, benefits and risks of blood donation so that informed consent can be obtained
- —
The balance between the benefit of an increased blood supply by recruiting younger donors against the increased risk of adverse reactions in this age group
- —
The increased iron requirement of adolescents and the possible compromise of their iron status by frequent blood donations
4.1.2. Upper age limit
Upper age limits for blood donation of between 60 and 70 years have been implemented in the past because of concerns regarding the increasing incidence of cardiovascular disease with age and the potential risk of adverse reactions, which are more likely in first-time donors.
There is now extensive published literature on the safety of blood donation in older individuals in both the allogeneic and autologous setting, indicating that vasovagal and other adverse reactions are infrequent in older donors who fulfil normal donor selection criteria (56,57,58,59,60). The upper age limit has been safely removed for regular blood donors in countries where healthy life expectancy is high (56,61,62,63,64). Nevertheless, many BTS have an upper age limit of 60 years for first-time donors.
Recommendations
In setting an upper age limit for blood donors, the BTS should consider the healthy life expectancy of the population
The usual upper age limit for blood donation is 65 years
First-time donors older than 60 years and regular donors over the age of 65 may be accepted at the discretion of the responsible physician
First-time donors over 60 years should make their first donation at a donation site where a physician is available
4.2. DONOR APPEARANCE AND INSPECTION
The prospective donor should appear generally well and should not be febrile, breathless or suffering from a persistent cough. Donors should be observed to rule out malnutrition or any debilitating condition. They should have a sound mental status and not be under the influence of alcohol or drugs.
The colour of exposed skin and mucous membranes should be normal, with no jaundice, cyanosis, flushing or pallor, and no signs of skin infection, rash or obviously enlarged lymph nodes. If body piercings or tattoos are present, the risk of transfusion-transmissible infections (TTI) should be assessed (also refer to Section 7.9.5 on cosmetic treatments and rituals).
The venepuncture site should be clean, free from any skin lesions or scars and the arms should be examined for signs of injecting drug use. Antecubital veins should be easily visible or palpable to enable proper venepuncture, thus avoiding any discomfort to the donor and minimizing the risk of major bruises or other soft tissue injury at the venepuncture site.
Donors with sight or hearing impairment may be accepted provided clear and confidential communication can be established. If assistance is required, it should be provided by a staff member or other independent person and not a family member or friend.
4.3. MINOR ILLNESSES
Minor non-specific symptoms (e.g. general malaise, pain, fever, headache, cough, diarrhoea) may indicate the presence of an acute infection that may be transmissible by transfusion. Donors should be asked to confirm that they are free from such symptoms on the day of donation and that they have fully recovered from any recent infection(s). Individuals suffering from minor illnesses and not feeling well should not donate blood.
There is no evidence that minor infections such as common upper respiratory infections can be transmitted by transfusion, but it is nevertheless advisable as a precautionary measure to defer blood donation until any such infection has resolved (65).
4.4. WEIGHT
It is important to set weight limits for blood donation to protect donors from adverse effects, in particular vasovagal episodes and anaemia. Low body weight and low blood volume have been shown to be independent predictors for vasovagal reactions (50,66).
It is generally accepted that the volume of whole blood donated should not exceed 13% of blood volume: e.g. a donor should weigh at least 45 kg to donate 350 ml (± 10%) or 50 kg to donate 450 ml ± 10% (67,68). There are no defined upper weight limits for blood donation; however, gross obesity may be a reason for deferral if veins are inaccessible, or if the donor's weight exceeds the safe loading capacity of the blood collection bed or impairs his/her mobility or the capacity of staff to provide care in the event of an adverse reaction. The estimation of blood volume is more difficult in obese individuals as fat contains proportionately less blood than muscle. Hence, blood volume may be overestimated (69), resulting in an increased risk of an adverse reaction.
For apheresis procedures, the total volume of donated plasma, platelets and red cells collected should not exceed 13% of total blood volume (70) and the maximum extracorporeal blood volume should not exceed 15% of the donor's total blood volume at any stage of the procedure. In practice, this requires that plateletpheresis and plasmapheresis donors should weigh at least 50 kg. Prospective donors of double red cell apheresis donations should have an estimated blood volume of more than 5 litres; this requirement is generally met by non-obese individuals weighing more than 70 kg.
The reasons for any obvious rapid weight loss should be ascertained.
Recommendations
In determining a lower weight limit for blood donors, the BTS should consider norms for the weight of the population; if a significant proportion of the donor population weighs less than 45 kg or 50 kg, collection volumes may be reduced accordingly, while ensuring that blood collection bags and their anticoagulant content are adjusted to be compatible with the volumes collected
Prospective donors of whole blood donations should weigh at least 45 kg to donate 350 ml ± 10% and 50 kg to donate 450 ml ± 10%
Prospective donors of apheresis platelet or plasma donations should weigh at least 50 kg
Prospective donors of double red cell apheresis donations should have an estimated blood volume of more than 5 litres; this requirement is generally met by non-obese individuals weighing more than 70 kg.
4.5. VITAL SIGNS
4.5.1. Pulse
A normal pulse rate of 60–100 per minute and a regular rhythm are indicators of good health; many BTS recommend that these are examined prior to donation. The ability to detect significant abnormalities of pulse rate or rhythm depends on the skill and experience of staff. The usefulness of this examination in a blood donation setting needs to be assessed.
4.5.2. Body temperature
A prospective donor who is febrile – defined as a core oral temperature more than 37.6°C (71) – is by definition unwell and should be deferred. Fever can indicate any number of medical conditions and infections, but is usually associated with other symptoms (also refer to Section 4.3 on minor illnesses).
4.5.3. Blood pressure (BP)
A normal blood pressure (systolic 120–129 mmHg, diastolic 80–89 mmHg) is generally regarded as an indicator of good health (72).
The measurement of BP is required by many national guidelines on donor selection and some BTS set an upper limit of BP for blood donors (70) on the basis that uncontrolled hypertension is an independent risk factor for cardiovascular disease. However, a systematic review of the literature found no evidence that raised baseline blood pressure, treated hypertension or low blood pressure were predictive of increased adverse reactions, although the level of evidence was limited (73).
BP may be measured routinely for the purposes of health screening; however, the blood collection session is not the ideal setting for this. Donor anxiety may result in the temporary elevation of systolic BP. Accurate BP measurement requires the availability of calibrated equipment, suitable facilities, adequate time and appropriately skilled staff.
Recommendations
In assessing whether pulse, temperature or blood pressure should be measured routinely, selectively or not at all at the time of blood donation, the BTS should consider:
- —
Clinical value of these parameters in the blood donation setting
- —
Availability of adequate equipment (calibrated and sterile, where appropriate), space and time. If blood pressure is used as a selection criterion for blood donation, arbitrary acceptable limits of systolic BP of 100–140 mmHg and arbitrary acceptable limits of diastolic BP of 60–90 mmHg are suggested
- —
Competence and experience of staff and their ability to perform techniques correctly
4.6. DONOR IRON STATUS
4.6.1. Haemoglobin screening
There are no rapid, simple and direct bedside methods for determining iron status. The pre-donation assessment of donor haemoglobin remains the best approach. Normal ranges for haemoglobin and red cell indices differ between ethnic populations, and in males and females, and are also affected by age, especially in women (74,75). International and national guidelines (Annex 1) commonly recommend minimum haemoglobin levels of 12.5 g/dl for females and 13.5 g/dl for males but further studies are needed to justify the selection of these levels. In some countries, the same haemoglobin level is used for males and females (76). Individuals with haemoglobin levels below the normal range are, by definition, anaemic (77). The WHO Global Database on Anaemia (55) defines haemoglobin thresholds for anaemia as 12.0 g/dl for non-pregnant women (≥15.00 years) and 13.0 g/dl for men (≥15.00 years). There are many causes of anaemia and anaemia due to iron deficiency is the most prevalent. The aim of haemoglobin screening is to ensure that the prospective donor is not anaemic. The lower limit of acceptable haemoglobin for blood donation should be set at a level that prevents the selection of anaemic individuals as blood donors and also minimizes the exclusion of healthy donors.
Haemoglobin screening safeguards anaemic individuals from donating blood and also protects returning donors from donation-induced iron deficiency (DIID), the depletion of iron stores by repeated donations (78,79). Collecting a unit of blood from a donor with a normal haemoglobin level also provides good quality blood components, with adequate and consistent haemoglobin content in the collected blood.
Haemoglobin and/or haematocrit are easily estimated by validated, simple, rapid and inexpensive methods, but are insensitive in assessing iron deficiency as values start to fall only when iron stores are depleted. Nevertheless, they remain the most convenient measurement parameters at blood donation session and when recorded at each subsequent attendance, can detect anaemia and DIID.
Donor haemoglobin and/or haematocrit levels should be measured immediately before each donation using a validated technique that is subject to quality control. Donors who do not meet the minimum haemoglobin levels for blood donation should be referred for further haematological investigation and treatment. They should be encouraged to return to donate when the anaemia has been successfully treated.
Recommendations
In determining the lower limits of haemoglobin for whole blood donation and implementing haemoglobin screening, the BTS should consider:
- —
Normal haemoglobin range among healthy individuals in the local population
- —
A haemoglobin level of not less than 12.0 g/dl for females and not less than 13.0 g/dl for males as the threshold
- —
Selection of a validated haemoglobin screening technique that is subject to quality control, the feasibility of its implementation, the availability of equipment and the training and skills of staff
Only sterile disposable lancets should be used for blood sampling
Donors whose haemoglobin levels are below the nationally-defined threshold should be deferred, counselled and referred for medical assessment
4.6.2. Frequency of donation and iron supplementation
Iron deficiency is common worldwide and donation-induced iron deficiency is of particular concern in relation to women of childbearing age and adolescents. Adolescents of both sexes are also at risk of iron deficiency during the pubertal growth spurt, when the average daily total requirement of dietary elemental iron to be absorbed is 1.50 mg/day for males and 1.62 mg/day for female (54,55). A donation of 450 ml of blood removes 200–250 mg of haem iron. The average amount of stored iron (ferritin and haemosiderin) in a woman of reproductive age in the developed world is about 300 mg; hence, the donation of a unit of blood requires the subsequent mobilization of much or all of this reserve (80). In developing countries, many women have depleted iron stores and will inevitably be precipitated into negative iron balance by blood donation (54,55,76).
Across the world, the minimum interval between whole blood donations varies between 56 days (8 weeks) and 16 weeks and different donation intervals are usually followed for male and female donors; in practice, some female donors are unable to give blood more than once or twice per year due to iron deficient states. There is a high prevalence of iron depletion in frequent blood donors; increasing the inter-donation interval would reduce the prevalence of iron depletion and deferral due to low haemoglobin (76,81,82).
The standard approach for preventing donation-induced iron deficiency is universal screening and deferring those whose pre-donation haemoglobin is below a certain threshold. It is important to detect and manage the donation-induced iron depletion that inevitably accompanies regular blood donation (78). Reducing the frequency of blood donation is likely to reduce the prevalence of iron deficiency among blood donors, as might implementing routine iron supplementation (83).
The onset of DIID may be determined using full blood cell counts and red cell indices, including red blood cell distribution width (RDW), when measured serially in healthy donors from populations with a low prevalence of inherited conditions such as thalassaemia trait. The more sophisticated red cell parameters on modern cell counters are even better indicators of DIID onset, even possibly in the co-presence of thalassaemia trait, but are more expensive and usually not available at blood donation sites.
Haemoglobin estimation alone in regular blood donors may not be adequate and serum ferritin estimations may need to be done to detect pre-clinical iron deficiency state. Regular ferritin measurement is a useful indicator for iron depletion in blood donors. (84,85,86,87,88).
If the BTS has access to facilities for monitoring donor iron stores by measuring serum ferritin concentrations, individual donor algorithms for donation frequency and iron supplementation may be developed (78,80,81,83,85,89,90,91,92,93). In some circumstances, the more expensive but informative determination of serum soluble transferrin receptor concentrations (STR) gives an even better indication of DIID.
Iron supplementation of blood donors has been proposed for routine implementation and several pilot operational and clinical trials have been conducted (83). Donor iron stores may be replenished by giving oral iron supplements and this particularly needs to be considered for repeat and regular blood donors.
Indiscriminate long-term supplementation with iron salts at a high dose is, however, not recommended, because of:
Possible masking of other pathological causes of iron deficiency, such as gastro-intestinal bleeding
Risk of giving iron salts to people with undiagnosed hereditary haemochromatosis or other inherited iron-overloading tendencies (
78)
Toxicity if accidentally ingested by children.
Some of these concerns may be avoided by using low-dose iron preparations or carbonyl iron. Such preparations are better tolerated, less toxic and can be safely used to reduce donation intervals.
Donors giving platelets or plasma by apheresis may donate more frequently than whole blood donors. A minimum inter-donation interval of 4 weeks for platelet donors and 2 weeks for plasma donors is generally recommended, provided that haematological and biochemical parameters are monitored and remain within acceptable limits (94). The interval before an apheresis platelet or plasma donation should be at least 4 weeks following a whole blood donation, an apheresis red cell donation or a failed return of red cells during apheresis (70).
The inter-donation interval between double red cell donations should be 6 months. If a double red cell donation is given following whole blood donation, the interval should be 12 weeks for males and 16 weeks for females.
Recommendations
The minimum interval between donations of whole blood should be 12 weeks for males and 16 weeks for females
The minimum interval between donations of platelets should be 4 weeks
The minimum interval between donations of plasma should be 2 weeks
The minimum interval before an apheresis platelet or plasma donation should be 4 weeks following a whole blood donation, an apheresis red cell donation or a failed return of red cells during apheresis
In determining the frequency of donation and whether iron supplementation is given, the BTS should consider:
- —
The need for longer donation intervals for young donors and female donors of childbearing age
- —
Assessing the feasibility and affordability of providing iron supplementation to donors susceptible to donation-induced iron deficiency, especially women, adolescents, and repeat and regular donors
- —
Exploring access to facilities for monitoring serum ferritin concentration and the feasibility of developing and implementing individual donation intervals
4.7. FLUID INTAKE AND FOOD
Most BTS guidelines recommend that donors should maintain their usual food and fluid intake before donation but should avoid heavy or fatty meals which may result in a lipaemic donation that may need to be discarded. The risk of adverse events in fasting donors has not been investigated, but there is evidence that an intake of 500 ml of drinking water immediately before donation may reduce the risk of a vasovagal reaction (95,96,97). Where possible, donors should have access to drinking water in the blood centre before donating. Fasting donors should have had some fluid intake in the four hours prior to donation. In countries where prolonged fasting is practised, blood collection sessions may be scheduled after they have taken food and fluid.
4.8. GENDER
4.8.1. Pregnancy, lactation and menstruation
The average woman needs about 350–500 mg additional iron to maintain iron balance during pregnancy (54,55). Female donors should be deferred during pregnancy and for a sufficient time after delivery (or following abortion or miscarriage) and during lactation to allow for the recovery of iron stores.
Menstruation is not a reason for deferral. However, women who report regular excessive menstrual bleeding and are found to have low haemoglobin levels should not donate blood and should be referred for medical assessment (90).
Contracting and relaxing the muscles in the legs, arms and abdomen during donation may reduce the risk of vasovagal reactions, particularly among female donors (98,99,100,101).
Recommendations
Accept
Defer
4.8.2. Reducing the risk of transfusion-associated acute lung injury (TRALI)
The gender of the donor may influence the type of blood component prepared from the donation. Plasma-rich blood components from multiparous women are more likely to cause TRALI and related disorders than those from males, because plasma from such women is likely to contain alloimmune-reactive antibodies; these include antibodies to human leucocyte antigens (HLA) or to human neutrophil antigens (HNA), which are transferred passively during transfusion, to the possible detriment of a recipient who possesses the corresponding antigen (102,103,104).
Recommendations
The BTS should consider:
- —
Maximizing the collection and production of plasma and platelet concentrates from male donors
- —
Screening multiparous female donors for HLA and/or HNA antibodies
4.9. OCCUPATION AND LEISURE ACTIVITIES
Delayed vasovagal reactions, defined as occurring after the donor leaves the blood donation site but within 24 hours of donation, are uncommon (reported as 46:100 000) (105). However, if the donor is in a hazardous situation, a delayed vasovagal reaction may put the donor and others at risk of harm. For this reason, most BTS advise donors in hazardous occupations (e.g. emergency services, working at heights) not to resume work for at least 24 hours after blood donation. Air crew are subject to their own regulations which do not permit blood donation within specified time limits (106). Similarly, donors are generally advised not to undertake strenuous physical activities for up to 24 hours after blood donation.
Some occupations (e.g. health-care workers, police, military personnel, workers with animals) carry an increased risk of exposure to blood-borne infections, although confirmed transmission is relatively rare (107,108,109,110,111). While such individuals should have been immunized against relevant diseases, where possible, donors in these occupations should be questioned about possible exposure risk (e.g. needlestick injuries, blood splashes, bites) and a deferral period, usually of 6–12 months applied, based on the incubation period of the relevant infection.
Sex workers are at particular risk of transfusion-transmissible infections and should not be accepted as blood donors (also refer to Section 7.9.1 on high-risk sexual behaviours).
4.10. SPECIAL CONSIDERATIONS FOR DONOR SELECTION FOR APHERESIS DONATIONS
Apheresis is the process by which the required component of whole blood is separated and collected from the donor using an automated blood cell separation device. Components that can be donated by apheresis include platelets (plateletpheresis), plasma (plasmapheresis), leucocytes (leucapheresis) and red blood cells (erythrocytapheresis).
Medical criteria for the acceptance of blood donors in respect of the donor's health should be the same for donors of whole blood and of blood components obtained by apheresis. Additional donor selection criteria pertaining to apheresis donations are recommended in the relevant sections in this document. Detailed recommendations regarding the volume and frequency of apheresis donations are outside the scope of these guidelines.
In addition to meeting the selection criteria required for whole blood donation, donors giving apheresis donations should also meet requirements that are specific for the type of apheresis procedure and the component collected (70,112,113,114). For apheresis platelet donation the donor's platelet count should be above 150 × 10 9/L. For apheresis plasma donation, the donor's total protein level should be greater than 60 g/L. For double red cell apheresis, donors of either gender require a minimum haemoglobin level of 14.0 g/dl (68).
