General Population BioResource

In the UK, men donate blood every 12 weeks and women donate every 16 weeks. But why follow these intervals? In over 100 years of blood donation practice, INTERVAL is the first-ever trial to assess the impact of varying the frequency of blood donation on donor health and the blood supply.

INTERVAL recruited blood donors. Men were randomly assigned to donate blood at 8-week, 10-week and 12-week intervals and women were randomly assigned to donate blood at 12-week, 14-week and 16-week intervals. Samples were collected and donors were asked to complete health questionnaires.

**Impact** Results from INTERVAL have shown that more frequent blood donations from donors can be done without causing harm to donor health. These findings have provided policy-makers (NHSBT) with evidence that more frequent collection from donors than is now standard can be done over two years without causing harm to donor health, allowing better management of the supply to the NHS of units of rare blood groups.

Analysis also showed that more intensive reminders to help donors keep appointments  increased whole blood donation rates. If more intensive reminders (e.g., a telephone call when an appointment is missed) could be done at little additional cost, then the gain in the amount of blood collected could be worthwhile, at least for priority blood groups.

To help protect the health of donors, it’s a requirement to find out whether a donor’s blood haemoglobin levels are adequate. Haemoglobin is an iron-containing protein found in red blood cells that carries oxygen around the body. Blood donor services have to measure haemoglobin levels in advance of each blood donation to protect the health of donors (e.g., to prevent anaemia) and to ensure the quality of blood products.

NHSBT measures the haemoglobin levels of donors by placing a drop of donor’s blood into a copper sulphate solution. If the drop sinks sufficiently, then it is judged that the donor’s haemoglobin levels are high enough to donate. If the drop doesn’t sink sufficiently, then a more accurate and costly test is used (‘HemoCue’). Alternative methods used by other blood services may be more accurate, donor-friendly and less time consuming. However, their comparative merits—and methods used by NHSBT—had not been thoroughly investigated until the COMPARE study.

**Impact** Results from COMPARE led to an evidence-based decision by NHSBT to replace the copper sulphate-based haemoglobin screening with finger-prick haemoglobin testing, thereby reducing the number of blood donors who are inappropriately bled in England. Results from this study have shaped NHSBT (and international) policy concerning haemoglobin screening.

In order to maintain donor health and secure regular blood donors—ensuring a sustainable blood supply—it is important to research the experiences of donors during the blood donation process and to determine ways in which the experience can be improved. This is the focus of the STRategies to Improve Donor ExperienceS (STRIDES) study.

The feasibility study ran from March to July 2019 and the main study began in November 2019.

We recruited five participants a day from the 73 NHSBT centres and reached 12,000 recruits by May 2020. As part of our study, we we do a full blood count, which enables the NHSBT to feed back to the participant any values, such as anaemia, that might have clinical importance.