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

Abstract

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.