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

Unadjusted appendicular skeletal muscle mass did not change significantly from pre- to post-transplantation, whereas adjusted ASM decreased significantly.

• Unadjusted ASM: median 17.7 kg pre-transplant to 17.5 kg post-transplant (p = 0.17, not significant)
• Adjusted ASM: median 17.6 kg pre-transplant to 17.2 kg post-transplant (p = 0.01, significant)
• After transplantation, adjusted ASM differed significantly from unadjusted ASM
• The correction formula was originally derived from the dialysis field for estimating ideal dry body weight

Phase angle, a measure of muscle quality, decreased significantly following allogeneic hematopoietic stem cell transplantation.

• Phase angle decreased from a median of 4.4° pre-transplant to 3.9° post-transplant (p < 0.001)
• Phase angle was used as an index of muscle quality assessed via BIA
• The decrease was assessed at 4 weeks after transplantation

The extracellular-to-total body water ratio (ECW/TBW) increased significantly following transplantation, indicating increased fluid retention.

• ECW/TBW increased from a median of 0.391 pre-transplant to 0.399 post-transplant (p < 0.001)
• ECW/TBW was used as an indicator of fluid balance
• The increase in body water content is the proposed mechanism by which BIA overestimates skeletal muscle mass in the post-transplant period

Physical function measures including knee extensor strength and six-minute walk distance (6MWD) decreased significantly after transplantation.

• Both knee extensor strength and 6MWD decreased significantly from pre- to post-transplantation
• Physical function was assessed before transplantation and 4 weeks after transplantation
• The decline in physical function measures was consistent with the decline seen in adjusted ASM and phase angle

The study included 64 adult patients who underwent allogeneic hematopoietic stem cell transplantation, with a median age of 51.5 years.

• Patient age range was 20–70 years with a median age of 51.5 years
• This was a retrospective observational study design
• Body composition was assessed using BIA measuring ASM, phase angle, and ECW/TBW before and 4 weeks after transplantation

BIA is sensitive to fluctuations in body water and can overestimate skeletal muscle mass, particularly in the early post-transplant period when body water content often increases.

• BIA is described as a simple, noninvasive method for evaluating skeletal muscle
• Overestimation of skeletal muscle mass by BIA may obscure true changes in muscle in the early post-transplant period
• A correction formula originally used in the dialysis field to estimate ideal dry weight was applied to skeletal muscle measurements to reduce this overestimation