Efficiency and safety of varying the frequency of whole blood donation (INTERVAL): a randomised trial of 45 000 donors.

A sufficient blood supply enables life-saving transfusions for many clinical situations, mostly in trauma and oncologic patients. Blood donor eligibility criteria differ in European countries and the US. As blood donation may cause iron deficiency, the donation interval is a matter of debate. Evidence-based data about safe blood donation frequency are missing and blood donation intervals have been set empirically to ensure donors’ health.

In this randomised, parallel-group prospective study, male donors were assigned to 12-week versus 10-week versus 8-week inter-donation intervals, and female donors to 16-week versus 14-week versus 12-week inter-donation intervals. The primary outcome was the number of blood donations over a 2-year observation period, while secondary outcomes, related to safety, were quality of life, donation-related symptoms, physical activity, cognitive function, haemoglobin and ferritin concentrations, and deferrals due to low haemoglobin.

Not surprisingly, the number of donations was increased in the short donation interval groups. Quality of life, physical activity, or cognitive functions were not significantly different across the groups. However, reducing inter-donation intervals resulted in an increased incidence of self-reported symptoms, lower haemoglobin and ferritin concentrations, and more deferrals.

This randomised trial showed that, in times of shrinking blood donor population, donation intervals can be modified without compromising donors’ quality of life, physical activity or cognitive function. Personally, I feel that donors’ ferritin levels should be closely monitored in intensified blood donation programmes so as to avoid iron deficiency.

– Rainer Moog