Ideal rather than actual body weight should be used to calculate cell dose in allogeneic hematopoietic stem cell transplantation

Whether the CD34+ and CD3+ cell doses in allogeneic HSCT should be estimated using actual (ABW) or ideal (IBW) body weight has never been definitively determined. We have shown that CD34+ cell doses based upon IBW are better predictive of engraftment after autologous and allogeneic HSCT. Sixty-three patients undergoing reduced-intensity HSCT after a uniform preparative regimen were evaluated to determine the effect of cell dose. ABW and IBW were 45 - 147kg (median 79) and 52 -85kg (median 67) respectively. The ABW-IBW difference was -24% to +133% (median +16%); nine patients were >5% underweight and 41 were >5% overweight. The CD34+ cell dose (10⁶/kg) was 1.4 -11.8 (median 5) by IBW and 1.2 -9.3 (median 4.5) by ABW. The CD3+ cell dose (10⁸/kg) was 0.9 -14.9 (median 3) by IBW and 0.7 -19.7 (median 2.7) by ABW. While CD34+ and CD3+ cell doses based upon IBW were found to affect transplant-related mortality, and disease-free and overall survival significantly, those based on ABW were either not predictive of outcome or the differences were of borderline significance. We suggest using IBW rather than ABW to calculate cell doses for HSCT; for statistical analyses and for clinical practice if a specific cell dose is being targeted.