Ideal or actual body weight to calculate CD34+ cell doses for autologous hematopoietic stem cell transplantation?

The number of CD34+ cells infused influences the speed of hematologic recovery post-transplant. There are limited data on whether ideal (IBW) or actual (ABW) body weight should be used to calculate CD34+ cell dose. We compared the correlation between recovery to 0.5 × 10⁹/l neutrophils and the CD34+ cell dose based upon ABW as well as IBW in 87 patients autografted for cancer. ABW was ≥25% over IBW in 43% of patients. The median number of CD34+ cells administered was 3.6 × 10⁶/kg ABW and 4.2 × 10⁶/kg IBW. The time to neutrophil recovery was 8-15 days (median 10). There was a stronger inverse correlation between CD34+ cell dose/IBW and neutrophil recovery (r² = 0.308; P <0.0001) than between CD34+ cell dose/ABW and neutrophil recovery (r² =0.267; P <0.0001). The median time to neutrophil recovery was comparable for those receiving ≥2 × 10⁶/kg CD34+ cefls/kg IBW as well as ABW (10 days) and those receiving ≥2 × 10⁶/kg CD34+ cells/kg IBW but <2/kg ABW (10 days), but was significantly slower for those receiving <2 × 10⁶/kg CD34+ cells/kg IBW (12 days). These data show that the CD34+ cell dose based on IBW is a better predictor of neutrophil recovery after autotransplantation.