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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

Opening blood donation centres on weekday evenings and at weekends is a cost-effective way of increasing the blood supply used by hospitals in the UK. Allowing donors to give blood more often could increase supplies in the short term, but it isn’t clear if it would be cost-effective in the long-term.

This NIHR-funded modelling study used data from a recent large randomised trial in the UK that investigated the safety of donating blood more frequently than current guidance allows. This was combined with current UK donation records, cost data, and the preferences of about 34,000 existing donors who were surveyed for this study.

The NHS Blood and Transplant service is looking for ways to increase supplies of blood types that are in high demand. This study adds to the evidence about which strategies are both clinically effective and cost-effective. This should help to inform future service changes.

Why was this study needed?

The NHS Blood and Transplant (NHSBT) service issued around 1.6 million units of red blood cells in 2015-16. While overall demand for blood has decreased in recent years, there is increasing demand for particular blood types. For example, the universal blood type (O negative) makes up about 13% of all hospital requests, but only around 7% of existing donors are blood type O negative.  Finding and retaining donors is expensive. So the NHSBT service needs to find alternative ways to ensure sufficient donations of high-demand blood types.  Encouraging existing donors to give blood more often might be one way of doing this.

This study aimed to identify cost-effective strategies for maintaining the blood supply.

What did this study do?

This health economics modelling study was made up of three parts:

  • A cost-effectiveness analysis of different minimum periods between donations, using data from the recent INTERVAL trial (a randomised trial of 45,263 whole-blood donors). The analysis used information on the number of donations, deferrals (temporary suspension from donating), and quality of life over two years.
  • Surveys of 25,187 participants from the INTERVAL trial and 9,318 other donors on donor preferences, including travel time, opening hours for appointments, and frequency of donations.
  • A cost-effectiveness analysis of alternative strategies, using data from the surveys and existing donor databases as well as evidence from the INTERVAL trial.

Cost-effectiveness was measured over one year, so longer-term effects were not considered.

What did it find?

  • In the INTERVAL trial, shorter intervals between donations increased the average number of whole-blood donations over two years. For men, the average number of donations increased by 1.71 (95% confidence interval [CI] 1.60 to 1.80) for the 8 vs 12-week interval arm of the trial, and by 0.79 (95% CI 0.70 to 0.88) for the 10 vs 12-week interval arm. For women, the increase was 0.85 (95% CI 0.78 to 0.92) for the 12 vs 16-week interval arm.
  • This increase in the average number of donations came at a small additional average cost compared with current practice. For example, the incremental cost-effectiveness ratio (ICER) was £9.51 for each donation/unit (95% CI £9.33 to £9.69) for men in the 8 vs 12-week interval arm of the trial. For women in the 12 vs 16-week interval arm, the ICER was £10.17 (95% CI £9.80 to £10.54).
  • The INTERVAL trial showed that shorter minimum donation intervals led to higher rates of deferral due to low haemoglobin levels. For men, the deferral rate was 5.7% per session in the 8-week interval arm, compared with 2.6% in the 12-week interval arm. For women, the rate was 7.9% in the 12-week interval and 5.1% in the 16-week interval.
  • The survey found that, for static donor centres (rather than mobile centres set up at specified times), making appointments available on weekday evenings and at weekends would increase the average frequency of donations per person by 0.5 per year.
  • The cost-effectiveness analysis found that extending opening times at all static centres to weekday evenings would provide additional units of blood at a cost of £23 per additional unit of blood. Extending to weekends at all static centres had a cost of £29 per additional unit of blood

What does current guidance say on this issue?

The Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee produces guidelines for the blood transfusion services in the UK. The section on the care and selection of donors says that an interval of 16 weeks between donations of whole blood is reasonable, with a minimum interval of 12 weeks. It also says that women should not donate more than three times in any 12-month period, and men can donate up to four times.

This is interpreted as men being able to donate every 12 weeks, and women being able to donate every 16 weeks.

What are the implications?

Extending opening hours to evenings and weekends at static donation centres is a relatively cost-effective way of increasing the blood supply. This could be targeted at donors whose blood types are in high demand to get the most value for the service. Other strategies like making mobile units available at weekends and producing health reports for donors were not cost-effective.

Shortening the time between donations also appeared a cost-effective way of providing additional blood in the short term, but also increases the rates of deferrals. Increasing deferrals may lead to people stopping donations altogether, which could bring higher costs that weren’t considered in this study and may not be cost-effective in the long term.

Citation and Funding

Grieve R, Willis S, De Corte K et al. Options for possible changes to the blood donation service: health economics modelling. Health Serv Deliv Res. 2018;6(40).

This project was funded by the Health Services and Delivery research programme of the National Institute for Health Research (project number 13/54/62).



Di Angelantonio E, Thompson SG, Kaptoge S et al. Efficiency and safety of varying the frequency of whole blood donation (INTERVAL): a randomised trial of 45 000 donors. Lancet. 2017;390:2360-7.

JPAC. Guidelines for the blood transfusion services in the United Kingdom. London: Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee; 2013.

NHS Blood and Transplant. Who can give blood? Bristol: NHS Blood and Transplant; accessed January 2019.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre


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