Potential benefits of an alternative haemoglobin deferral strategy evaluated in seven countries

On-site donor deferral for low haemoglobin (Hb) levels poses significant challenges for blood establishments globally, leading to material wastage and consumption of valuable staff and donor time. Traditionally, donors are deferred based on a single visit's Hb measurement, without considering previous Hb levels and measurement variability. This study aims to quantify, in different settings, the potential impact of an alternative deferral algorithm based on historical mean Hb levels.

We retrospectively reassessed donor eligibility in 20,430,816 donations and deferrals in Australia, Belgium, Finland, France, the Netherlands, South Africa and the United States using an algorithm that considers a repeat donor eligible as long as their historical mean Hb is above the deferral threshold and deviations from the mean are consistent with anticipated measurement variability. We quantified the potential impact of the alternative algorithm by calculating the change in donations and deferrals.

Across countries, the alternative algorithm may reduce low Hb deferrals between 30% and 70%. Additionally, in every country, a small proportion of current donors (~1%) donate who exhibit consistent low Hb levels. Balancing new deferrals and donations, the estimated net increase in donations across countries ranges between 0.7% and 3.3%.

The alternative deferral algorithm based on mean Hb levels is a first step towards a more comprehensive assessment of Hb levels to determine donor eligibility. Further research is needed to refine the algorithm, to determine its long-term impact, to improve the model with information related to iron stores and recovery and to address the impact on donor safety.