What is the impact of whole-blood donation frequency on donor health? A systematic review

To maintain a stable blood supply while protecting donor and recipient health, the World Health Organization (WHO) recommends minimum inter-donation intervals of 12 weeks for men and 16 weeks for women. These recommendations are merely based on observational studies reporting reduced haemoglobin (Hb) and iron levels and increased deferrals in repeat donors. This systematic review aims to examine the best available experimental evidence on how whole-blood donation frequency impacts donor health.

PubMed (Medline, PMC and NCBI Bookshelf), Embase and the Cochrane Library were systematically searched by two reviewers independently. Risk of bias and certainty of evidence were evaluated using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach.

Four records on three randomized controlled trials (RCTs) were included. The results showed that donating every 12 weeks may reduce Hb and ferritin levels compared to not donating. Similarly, shortening inter-donation intervals (from 12 to 8 or 10 weeks for men and from 16 to 12 or 14 weeks for women) may lead to decreased Hb and ferritin levels, increased low-Hb deferral and increased reporting of tiredness, fainting, dizziness and restless legs. Evidence was of low to very low certainty, and limitations in study design and imprecision prohibit strong recommendations on optimal inter-donation intervals.

In the absence of more robust evidence and pending future high-quality RCTs, it is prudent to adhere to the current WHO guidelines on minimum inter-donation intervals for whole-blood donation, that is, 12 weeks for men and 16 weeks for women, as a precautionary measure.