Peripheral blood stem cell yield calculated using preapheresis absolute CD34+ cell count, peripheral blood volume processed, and donor body weight accurately predicts actual yield at multiple centers

Background Accurate prediction of stem cell yield is important for planning leukapheresis procedures. A formula has been published (Pierelli et al., Vox Sang 2006;91:126-34) to estimate the CD34+ dose collected on the first day of leukapheresis that was based on the preapheresis peripheral blood (PB) CD34+ counts, the blood volume processed, and the donor's weight. The aim of this study was to assess the predictive value of this formula. Study Design and Methods Data were retrospectively collected on 1126 consecutive PB stem cell harvests conducted at five institutions. Information on age, sex, diagnosis, weight, preapheresis absolute peripheral CD34+ count, total blood volume processed, and CD34+ cells harvested per kilogram of body weight on the first day of apheresis was collected. Results Among donors at least 18 years old, Pearson's correlation coefficient (r) between actual yield (AY) and predicted yield (PY) was 0.76. To characterize this correlation, AY and PY were classified as being within the conventionally acceptable CD34+ doses (>2 × 10⁶-5 × 10⁶ cells/kg), below this range (≤2 × 10⁶ cells/kg), or above it (>5 × 10⁶ cells/kg). The positive predictive value (PPV) of PY was estimated considering the distribution of AY as the "gold standard." PPV was relatively high for PY of more than 5 × 10⁶ cells/kg (85%), moderate for PY of not more than 2 × 10⁶ cells/kg (72%), and low for PY more than 2 × 10⁶ to 5 × 10⁶ cells/kg (56%). A consistent pattern was observed within institutions. Conclusion The formula of Pierelli et al. is associated with a PPV that is high, moderate, and relatively low for the corresponding predicted CD34+ doses.