Well done to the NHS. In the UK currently less than 4% of the eligible population donate blood and that is likely to decrease with aging population. A large study (n=50k approx) of this kind is helpful not just in England but for other countries to analyse the results. This was only possible in a national health service where the demographics made it possible to get a large cohort with a consistent approach.
“No one knows what the optimum interval between donations is, blood donation services in different countries have developed varying customs. In England, men are invited to donate every 12 weeks and women every 16 weeks. This is a relatively long interval compared to other European countries; the figure below shows inter-donation intervals for men and women across 14 European countries.Between June 2012 and June 2014, the INTERVAL study recruited about 25,000 men and about 25,000 women at NHS Blood and Transplant (NSHBT) blood donation centres across England” 1
During the study participants were asked to give blood either at usual donation intervals or more frequently. Men donated every 12, 10 or 8 weeks and women every 16, 14 or 12 weeks. The researchers are comparing the amount of blood donated and measures of well-being in people asked to give blood at standard intervals versus those asked to give blood more frequently.
It was incredibly easy to take part because they just did as part of the regular donation and it’s great for the researchers to provide a really useful outcome.