Decrease in Psoas Muscle Mass and Density Following Liver Transplantation Is Greatest in Patients With the Highest Muscle Quantity and Density Pre-Transplant.

Psoas muscle area index (PAI) decreased by 12% overall following liver transplantation.

• Mean PAI pre-transplant was 7.94 cm2/m2 and 6.99 cm2/m2 post-transplant.
• 104 adult liver transplant recipients had pre- and post-transplant CT scans analyzed.
• PAI was derived from computed tomography (CT) imaging.
• The reduction represents a mean loss of approximately 0.95 cm2/m2.

Mean Hounsfield units (mHU), a measure of psoas muscle density, decreased by 7% overall following liver transplantation.

• Mean mHU pre-transplant was 35.47 and 33.00 post-transplant.
• This represents a reduction of approximately 2.47 Hounsfield units.
• mHU was assessed from CT-derived measurements of the psoas muscle.
• Sample included 104 adult liver transplant recipients.

The reduction in PAI following liver transplantation was greatest in patients with the highest pre-transplant muscle mass.

• PAI reduction was -15% for the upper quartile, -12% for the mid-two quartiles, and -6% for the lower quartile.
• The difference across pre-transplant quartiles was statistically significant (p value = 0.0028).
• Patients were stratified by pre-transplant PAI quartiles.
• This indicates an inverse relationship between pre-transplant muscle mass and relative muscle mass loss post-transplant.

The reduction in mHU following liver transplantation was greatest in patients with the highest pre-transplant muscle density, while the lowest quartile showed a muscle density increase.

• mHU stratification by pre-transplant quartile showed -15% for the upper quartile, -8% for the mid-two quartiles, and +12% for the lower quartile.
• The difference across pre-transplant quartiles was statistically significant (p value = 0.0004).
• Patients in the lowest pre-transplant mHU quartile actually gained muscle density post-transplant (+12%).
• This suggests that patients with the lowest baseline muscle density may experience a different post-transplant trajectory than those with higher baseline density.

No relationship was found between PAI and mHU, suggesting muscle mass and muscle composition are independently affected following liver transplantation.

• PAI measures psoas muscle area index (quantity), while mHU measures mean Hounsfield units (density/composition).
• The paper states: 'No relationship was noted between PAI and mHU.'
• The authors conclude that 'muscle mass (PAI) and composition (mHU) appear to be affected by multiple factors.'
• This finding implies that muscle quantity and muscle quality should be assessed separately in liver transplant patients.

Sarcopenia assessed via CT-derived psoas measurements is a known predictor of morbidity and mortality after liver transplantation, but data on post-transplant changes in psoas muscle area and density are scarce.

• The authors note 'a paucity of data exists describing the change in psoas muscle area and density from pre- to post-liver transplant.'
• Sarcopenia has been assessed using CT-derived Psoas Area Index (PAI) and mean Hounsfield units (mHU).
• Literature is described as 'abundant regarding the adverse outcomes of liver transplant in sarcopenic patients.'
• This study of 104 patients addresses the identified gap in longitudinal post-transplant muscle assessment.