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

The number of CD34+ cells infused influences hematologic recovery after transplantation. Limited data suggest that cell dose should be based on ideal (IBW) rather than actual (ABW) body weight for autotransplantation, but none in allografts. We compared the correlation between recovery to 0.5 x 10(9)/l neutrophils and the CD34+ cell dose based upon ABW and IBW in 78 allograft recipients. ABW was greater than or equal to25% over IBW in 47% of patients. The median CD34+ cell dose was 5.1 x 10(6)/kg IBW and 4.4 x 10(6)/kg ABW. The time to neutrophil recovery was 8-26 days ( median 12). There was a stronger inverse correlation between CD34+ cell dose/IBW and neutrophil recovery (r(2) = 0.160; P<0.0001) than between CD34+ cell dose/ABW and neutrophil recovery (r(2) = 0.138; P = 0.001). When neutrophil recovery in patients receiving <3 or <5 x 10(6) CD34+ cells/kg was compared to those receiving greater than or equal to3 or greater than or equal to5 x 10(6) CD34+ cells/kg, respectively, separately by IBW and ABW, the magnitude and significance of the differences were greater for IBW-based comparisons. These data suggest the CD34_ cell dose based on IBW is a better predictor of neutrophil recovery after allografting. Further work in a larger, more homogeneous group of patients is required to confirm this observation.