Actual or ideal body weight to calculate CD34+ cell dose in patients undergoing autologous hematopoietic SCT for myeloma?

CD34+ cell dose calculations are usually based on actual body weight (ABW). We have shown that ideal body weight (IBW) may provide a better basis for this in a small population of patients with hematologic malignancies. This was studied further in 514 myeloma autografts. The CD34+ cell doses (106/kg) by IBW and ABW were 1.37–39.36 (median 6.03) and 1.15–29.67 (median 4.84), respectively. IBW-based cell doses correlated slightly better with engraftment than ABW-based doses (higher r2): 0.5 × 109/l neutrophils 0.83 versus 0.82, 1.0 × 109/l neutrophils 0.78 versus 0.77, 20 × 109/l platelets 0.54 versus 0.53 and 50 × 109/l platelets 0.57 versus 0.55. When outliers (hematologic recovery in <8 or >16 days) were excluded, the findings were similar: 0.5 × 109/l neutrophils 0.85 versus 0.84, 1.0 × 109/l neutrophils 0.85 versus 0.84, 20 × 109/l platelets 0.86 versus 0.85 and 50 × 109/l platelets 0.85 versus 0.84. CD34+ cell doses based on IBW as well as ABW significantly affected engraftment when analyzed separately as continuous variables. However, when analyzed together, only the dose based on IBW retained significance. We conclude that calculation of CD34+ cell numbers for autotransplantation should be based on IBW.