Evaluation of skeletal muscle indicators following allogeneic hematopoietic stem cell transplantation: verification of skeletal muscle mass adjustment.

purposeBioelectrical impedance analysis (BIA) has emerged as a simple, noninvasive method for evaluating skeletal muscle. However, BIA is sensitive to fluctuations in body water and can overestimate skeletal muscle mass, which may obscure true changes, particularly in the early post-transplant period, when body water content often increases. In this study, we explored whether correction formulas originally used in the dialysis field to estimate ideal dry weight could be applied to skeletal muscle measurements to reduce overestimation of skeletal muscle mass.

methodsThis retrospective observational study included patients who underwent allogeneic hematopoietic stem cell transplantation. Physical function and body composition were assessed before transplantation and 4 weeks after transplantation. Physical function was evaluated using knee extensor strength and the six-minute walk distance (6MWD). Body composition was assessed using appendicular skeletal muscle mass (ASM) as an index of muscle quantity, phase angle as an index of muscle quality, and the extracellular-to-total body water ratio (ECW/TBW) as an indicator of fluid balance. A correction formula for estimating ideal dry body weight was applied to adjust ASM. Differences between unadjusted and adjusted ASM were compared at each time point. Pre- and post-transplant changes in phase angle and ECW/TBW were also evaluated.

resultsSixty-four adult patients aged 20-70 years (median age, 51.5 years) were included. After transplantation, adjusted ASM differed significantly from unadjusted ASM. Knee extensor strength, 6MWD, and phase angle (median, 4.4°to 3.9°, p < 0.001) decreased significantly, whereas ECW/TBW increased significantly (median, 0.391 to 0.399; p < 0.001). Unadjusted ASM did not change significantly from pre- to post-transplantation (median, 17.7 to 17.5 kg; p = 0.17), whereas adjusted ASM decreased significantly (median, 17.6 to 17.2 kg; p = 0.01).

conclusionApplying a dialysis-derived adjustment formula to skeletal muscle measurements may help correct overestimation of skeletal muscle mass due to increased body water content in the early post-transplant period. After transplantation, both adjusted ASM and phase angle decreased significantly. These results suggest that BIA may have potential utility during the immediate post-transplant period, although its clinical applicability requires further validation.