Abstract
<title>Abstract</title> <p>Background Longitudinal changes in skeletal muscle mass and quality after allogeneic hematopoietic stem cell transplantation remain unclear. This study used bioelectrical impedance analysis to assess these changes and their associations with physical function, infection, and acute graft-versus-host disease. Methods This retrospective study included 111 adults who underwent allogeneic hematopoietic stem cell transplantation. Skeletal muscle mass index and phase angle, an indicator of muscle quality, were assessed by bioelectrical impedance analysis before transplantation, 4 weeks after transplantation, and at discharge. Patients were assigned to four combined categories based on normal or low muscle mass and quality. Outcomes included 6-minute walk distance, infection, and acute graft-versus-host disease. Results Skeletal muscle mass index and phase angle decreased significantly after transplantation (p < 0.05), with phase angle declining earlier and more markedly. At discharge, 53.1% of patients were classified as Category 3. At 4 weeks, the decline in 6-minute walk distance was significantly greater in Categories 2 and 3 than in Categories 0 and 1. In multivariable analyses, Categories 2 and 3 were independently associated with infection, whereas Category 3 was independently associated with acute graft-versus-host disease. Conclusion Skeletal muscle mass and quality deteriorated after allogeneic hematopoietic stem cell transplantation, and low muscle quality was more closely associated with adverse outcomes. Pre-transplant bioelectrical impedance analysis-based assessment of muscle quality may help identify patients at risk of infection, acute graft-versus-host disease, and delayed physical recovery and may support further evaluation of prehabilitation strategies.</p>