Prediction of blood volume to be processed to achieve a target number of CD34+ cells: Development, validation and implementation of a formula

Calculation of blood volume (BV) to be processed to achieve the target number of CD34+ cells can be accomplished by using collection efficiency 2 (CE2) formula. Our aim was to develop a BV web formula.

We calculated CE2 from aphereses performed between January 2015 and March 2020 in allogeneic donors and patients. From May 2020 to May 2021, we validated a formula: BV = ((Target CD34+ cells in the product)/(CD34+ pre-apheresis cells × CE2)) × 100. Subsequently, we compared the outcome of the procedures carried out before formula implementation (pre-formula), when standard three total BV collection was performed.

CE2 was assessed in 384 apheresis procedures before formula implementation. CE2 was higher in allogeneic donors than in patients (53% ± 17% vs. 48% ± 15%, p = 0.008). CE2 was higher in multiple myeloma and non-Hodgkin lymphoma than Hodgkin's lymphoma (48% ± 15%, 48% ± 15% and 42% ± 13%, respectively; p = 0.008). Our formula (available on a website: Publisheet) was prospectively used in 54 individuals. The formula was very accurate: predicted versus observed CD34 + cells/kg collected had an r-value of 0.89 (p < 0.0001). We compared their results with 78 pre-formula individuals. In the post-formula group, a greater BV was processed in patients and less BV in allogeneic donors. Among individuals under 60 years of age, it was significantly less frequent than the need for more than one apheresis in the post-formula group.

Formula calculations were accurate. Formula implementation allowed the optimization of the procedures and reduced the rate of individuals in need of apheresis for more than 1 day.