Comparison of autologous peripheral blood stem cell dosing by ideal vs actual body weight

In this retrospective study, we evaluated the predictability of PBSC dose for hematopoietic engraftment comparing that calculated by ideal body weight (IBW) vs another calculated by actual body weight (ABW) for each patient. Sixty-three consecutive patients treated similarly using one transplant protocol were analyzed. While all patients had data available on CFU-GM and nucleated cells (NC), data on CD34+ enumeration was present only in 34 patients. We found that 49% of the patients were greater than 25% over their IBW. In addition, least-squares linear regression was used to assess the strength of the linear relationship between the inverse of cell dose/kg of ABW or IBW and time to AGC or platelet engraftment and showed no difference in r2 values for platelet engraftment, while using dose/kg of IBW greatly improved the ability of NC (r2 improved from 0.19 for ABW to 0.35 for IBW) and CFU-GM (r2 improved from 0.35 for ABW to 0.53 for IBW) to predict time to AGC engraftment, but did not change the CD34 r2. Hazard ratios were estimated using Cox proportional hazards regression and in all instances were found greater than 1.0 indicating that the probability of engraftment increased as cell dose/kg ABW or IBW increased. Finally, our data showed that 10 patients (16%) could have had one less apheresis procedure performed to obtain their set target stem cell dose calculated per kg IBW rather than ABW. In conclusion, PBSC dose per kg IBW is as good or better predictor of engraftment of AGC and may lead to cost savings in a certain subset of patients.