The use of adjusted ideal body weight for overweight patients undergoing HPC mobilisation for autologous transplantation.

Generally, patients' actual body weight (ABW) is used to calculate the number of CD34⁺ cells to be harvested for autologous haematopoietic progenitor cell (HPC) transplantation. In our institution, 'overweight' patients weighing at least 25% more than their ideal body weight (IBW) have their adjusted ideal body weight (AdjIBW) used for determination of blood volume to be processed to achieve a minimum target of CD34⁺ cells per kilogram, as well as CD34⁺ cell dosage calculation at transplant. AdjIBW is calculated as follows: AdjIBW = IBW + 0.25 × (actual weight - IBW). We have used AdjIBW for 65/153 patients who have had autologous HPC harvests, with a median AdjIBW of 69 kg (range, 50-110 kg). Median actual weight was 90 kg (range, 62-175 kg). Median volume of peripheral blood processed to achieve a minimum 2 × 10⁶ CD34⁺ cells/kg for these patients was 13.2 L (range, 5-35 L), and the median CD34⁺ cells × 10⁶/kg collected for AdjIBW was 6.3 (range, 1.7-33). For normal-weight patients (n = 88; median ABW, 75 kg; range, 49-98 kg), the corresponding median apheresis volume was 16 L (range, 7-24 L), and median CD34⁺ cells × 10⁶/kg harvested was 4.5 (range, 1.4-15.9). In total, 35 in a total transplant cohort of 82 patients had AdjIBW used to determine CD34⁺ cell dose at time of transplant, with a median of 4.5 × 10⁶/kg, (if their ABW was used in the calculation; 3.1 × 10⁶/kg), compared to median dose of 3.2 × 10⁶/kg ABW for the normal-weight patient cohort. All patients engrafted with no significant difference between median times to neutrophil and platelet engraftment for the overweight (13 and 15 days, respectively) compared with normal-weight (12 and 14 days, respectively) patient cohorts. We conclude that the use of AdjIBW is a useful tool for successful harvest and subsequent transplant for overweight patients, with no adverse effect on engraftment times.